| Nose Radius! (Nov 18,
2001) |
Help with brazed on Chinese
carbide tools (Jun 26, 2003) |
| Cutting remarks (Nov 19,
2001) |
Carbide inserts vs grinding your
own bits (Aug 16, 2003) |
| Best
grinding wheels for HSS/Carbide Bits? (Nov 23, 2001) |
Grinding lathe bits on HF
carbide tool grinder? (Aug 29, 2003) |
| Indexable tools?
(Dec 25, 2001) |
Cutter for graphite?
(Dec 12, 2003) |
| What speed and hp grinder to use?
(Mar 11, 2002) |
Zen and The Art of Grinding
Lathe Bits (Dec 26, 2003) |
| Cutting tool material
(Jul 2, 2002) |
Finishing tools (Jan 26,
2004) |
| Cutting Tool Sources?
(Sep 14, 2002) |
Cutting tools stainless steel
(Feb 8, 2004) |
| What Lathe Bits Do You Use?
(Nov 14, 2002) |
Cutter bit gauge (Mar
12, 2004) |
| Cutoff tool use (Dec 31,
2002) |
Who uses indexable inserts
(Jun 11, 2004) |
| Spherical Turning tool
(Jan 27, 2003) |
H.S. steel inserts (Jul
13, 2004) |
| Tool Bits ? (Mar 31,
2003) |
Best tool for a smooth finish?
(Nov 10, 2004) |
| Cut off tools (Apr 27,
2003) |
Cutter bit grinding block
(Dec 1, 2004) |
| Cutter size (May 23,
2003) |
Carbide tooling - Doing
something wrong? (Jan 4, 2005) |
| Tooling info/advice (Jun
12, 2003) |
Radius tools (Feb 23,
2005) |
| About turning tool inserts
(Jun 13, 2003) |
Tooling dealers in Richmond VA
area? (Mar 16, 2005) |
| |
| Nose Radius! |
| I've owned a 9"
south bend since 1997 and a 13" since 1999, and just today I finally
figured out how to make them take a cut of decent depth. Buy the 321
size carbide inserts. Not 322 or 323 with the large nose radius, but
sharp little 321's with the 1/64" nose radius. What happens with the
bigger ones is that the nose just rubs without cutting, the belt
hops off the cone pulleys, and when you back the tool out of the jam
you find that the corner is broken off. These belt drive lathes
simply do not have the horsepower for the large nose radius inserts.
One can at best take very light cuts with the larger nose radii, but
the cut really has to be as deep as the radius for things to work
properly. In other words, all the inserts I bought before my most
recent order are useless junk. Iron, steel, whatever, it all turns
like butter now. I couldn't believe it and had to put a TNMP 322
back in the same holder to double check... same old rubbing cut -
put in the 321 and it acts like a serious tool. If anyone else out
there has been banging their head against the wall wondering why
they can't take off more than .015" from radius in a pass, get a
sharper nose, set the edge perpendicular to the axis, and watch in
amazement as the little 9" lathe removes a quarter inch of material
(1/8 off the radius) at a time. Okay, I guess most of you already
knew this, but wow, I can't believe how much time and effort I've
wasted figuring it out! Chris
(2194) |
| Chris, You may be able to get a
deeper cut still with a sharp HSS tool as well. How much do you want
for all those 323 inserts you don't need now? I've found that I get
a much better finish with a larger nose radius. Of course, I'm
taking a very light cut for the finish cut. George (2195) |
| So why is it all
the books show the roughing tool with a bigger radius? Is it because
a roughing cut is bigger than the nose radius and a finishing cut is
smaller than the radius on a roughing tool?
(2200) |
| Lurch, A larger tool nose radius last
longer. It takes more pressure though to cut the steel (in a certain
way of thinking). Your depth of cut should be enough for the TNR to
be covered by the steel or the tool will have more pressure pushing
from the part. Your depth of cut should be twice the TNR or a bit
more. That is why smaller TNR's are used for the final cut. Remember
that your feed should match (or be smaller) than the TNR to achieve
a better finish. I know people use larger TNR to finish a cut, I
sometime do to. With different steel some tool geometry works better
than others. That's why Iscar, Kennemetal etc. make some many
inserts. Also to make a buck or two. Tom (2202) |
| There's always a
trade-off with the strength of the cutting edge. The "books" are
usually for a machine shop which will have different production
needs than a home shop. You can make a small lathe take much bigger
cuts with a sharper edged tool, the trade-off being you will have to
sharpen the bit more often. I've found I can get a good finish on
even a fairly sharp tool, but I have to slow the feed rate down
more. George
(2215) |
| Cutting remarks
|
| Some things do not
change with the times. Like roughing for example. Everybody has
their own way of working down a diameter. My 10 cent theory is this.
TOOL MAKING 101 Take a tool bit and grind it using 1 set-up on the
grinder stage. Five degrees is a good start. Looking down on the
tool, draw a line across the end of it, left to right. Slope the line
at 10 degrees away from the left-hand edge. That is your front
clearance. Of course you have already set the grinder stage at 5
degrees. Now put the left side of the cutter up against the wheel
with the tool held firmly to the stage. Grind the cutter until you
get a nice hollow from top to bottom. Now place the tool so that the
top of the cutter is engaged in the stone. KANT THE CUTTER so that
the heel gets cut more then the end. This is a compound cut. You are
shaping the bit so the LEFT HAND edge and tip are the highest point
on the cutter. So what you now have is a tool that looks slightly
off square and is hollow-ground so the cutting edges that will
engage the metal with enough clearance. Now put the bit back on the
stage and pivot the left hand corner on the wheel. This gives you a
perfect radius that blends both side and front edges. A 1/16" radii
is plenty. Now you have a cutter that looks machine sharpened and
better then professional. Before using it, take a fine India stone
and rub it carefully on the cutter by following the contour right to
left on the face. (Hold the cutter in a clamp for this) You press
the stone so that it just sits on the cutter a bit proud of the
front edge. Now stone the top 1 or 2 strokes leaving a tiny 'jointed
edge'. USING THE TOOL Place the bit on center using a pocket scale
between the stock and bit. When it is sticking straight up tighten
it down. If you have a flat belt lathe, roughen the driving-side
with some scotch-bright to remove the glaze. Set the lathe in
GrandMa, (back-gear) Start the lathe in high -range low-gear. Begin
with .060 on the dial. Now what did you forget? 1.Snug tool up over
center of the tool-post. Compound is set so that tool post is close
to compound pivot. 2. Oil can and brush or better yet a drip can. 3.
Set feed about 3 notches from dead-slow. IN GENERAL, this is a point
of departure. You may be able to go faster with your speed and feed.
The tool should be dressed after 5 passes if your taking off a lot
of stock. The hand stone is the best method without taking out the
cutter. One of the advantages of this method is your cutter produces
a square shoulder. The other is that you have a lot of meat behind
the cutting edge. Also, the cutter is cheap. I have roughing and
finishing tools. If you have head-space problems near the tail-stock
center, just rough-grind the right side of the bit for clearance. And
for the record, I have very few carbide tools. A $5 1/2X1/2X4" MOMAX
is a lot cheaper then a $10 insert that you must buy a $20 holder
for. I am a great believer in real HSS. Ron (2196) |
| HSS
certainly is useful for many jobs, however I find it just does not
hold up very long taking heavy cuts in cast iron. The carbide
doesn't care how hot you run or how hard the material is, and a
southbend lathe can't turn too fast for it until you get to a
substantial workpiece diameter. The two sided carbide inserts
(TNMP321) are about $6, each corner lasts substantially longer than
the time between re-sharpening HSS, and there are six corners per
insert that are all the same. It seems the narrow nose radius does
not jam as severely as the larger radii inserts, so these are
actually more likely to survive a belt jump intact. The holders are
easy to make - taking about five minutes apiece once you setup a
fixture on a mill with the appropriate 7-degree droop angle. - just
two passes with a 3/8" end mill, drill, and tap. I keep both HSS
cutters and carbide inserts around, as neither one alone is suitable
for all tasks. There are times when HSS might work, perhaps even be
the best choice, that I reach for the carbide instead because I
don't want to go all the way down to the basement to the grinder and
swap out the buffing wheels that are often on it for grindstones.
Chris (2197) |
| That is pretty much
exactly how I do it. My question is, although I don't get the tool
anywhere near hot enough to discolor during the grinding process, do
I gain anything by heating it nice and red, quenching, and drawing
it down to straw color afterwards? Or are the HSS and cobalt blanks
sold everywhere already hardened and tempered? The reason I ask, is
my attempts to do so on a practice blank, an odd one that came with
the lathe but fits none of my toolholders, I heat to cherry-red with
my old gasoline blowtorch and just quench the last inch, then pull
it from the water and wait for the colors to run from the stored
heat in the unquenched part, then quench the whole thing and I
don't seem to be able to get to straw color, although an overall
wild purple-brown is certainly easy to achieve. Perhaps quenching
the whole thing and tempering it in the toaster-oven is more
appropriate? (2199) |
| Lurch, You
shouldn't heat treat the HSS blanks. I don't think it hurts, but
isn't necessary. HSS should be an air hardening steel. You may be
damaging the steel to some extent. You also shouldn't heat treat
carbide either. Just keep them cool with an occasional dip in water
during grinding. With carbide, it is best to have a constant flow of
water on the grinding wheel. This might not be possible with your
setup. As far as quenching, some steels are oil quenching others are
water quenching, HSS should be air quenching. With the water types,
we always used a saltwater (brine) mixture to quench these. Regular
water would build up air pockets, thus not allowing the steel to
cool. Air is a great insulator. The salt prevented this. You have to
be quick to draw to a straw color also. Heating in an oven is
preferable. Letting the colors run the length of the tool shank
results in a stronger tool shank, with the tip being hard.
Lurch (2201) |
| You should avoid
overheating the tool bit as you grind it. The HHS is in the state it
needs to be in for the use in the cutting of metal, Any over heating
will only detract from the performance of the tool. You would only
do what you are talking about if you were starting with for example
precision ground flat stock which is in a "soft" state when you buy
it. Yasmiin (2206) |
| Got it. HSS tools,
if not overheated during grinding, are fine to use out of the box.
Can I assume the heat-treating/quenching/tempering instructions in
my ancient [1941] copy of "Encyclopedia Of Machine Shop Practice"
are for CARBON steel, NOT high-speed steel (2208) |
| Correct. In
general, HSS can't be hardened in the home shop. It requires
temperatures far in excess of most home shop equipment. Also,
without knowing the exact composition of the steel you had, you
would most probably just crack it. George
(2211) |
| Lurch, yes that's
correct. I would watch out for TANTUNG though. It is a harder HSS
used in the screw-machine field for its longevity. If you get this
to hot during grinding it will crack! On the other hand, if you can
lay your hands on some liquid nitrogen, 'cook' your tool-bits in
this stuff when not in use. It will toughen them. As for your
tooling problems, what the hell IS a lantern Tool-post? Is this a
term for the old style tool holder? The 4-way tool-holder is only
good for short un-supported work in the chuck or face-plate. It gets
in the way of long shaft work held in the tail-stock. It's best used
in a limited-production situation. I would second the opinion of
Chris. Buy an Aloris TP, matching dove-tail cutter, and hot-rolled
steel. Make your own. I'll coach you through it so that you will end
up with a better set then anything Horror Freight can sell, (Hmmm,
not saying much huh?). My own arrangement of tool-holders goes
something like this: 1 left,1right(with groove for small B-bars) 1
C/O,1 boring bar,(1" thru-hole) 1, threading(60`) 1deep-throat,1
knarler These tools are indispensable . And speaking of tooling, you
should have a dedicated set of tools on a tool-board located at the
back-right end of your lathe. The board should have spaces for a
dozen bits, and holes for wrenches and tail-stock tooling. Make it out
of pine and slanted at a 45` angle. You should have a wrench for the
compound set-screws, cross-feed screws, tool-post, chuck wrenches.
OTHER TOOLING -oval brush for cleaning chips -goose-neck lamp over
lathe -thread cleaner for chucks -bore-brush (brass or copper) -6"
scale .030 thick - oil can for lube, keep tip clean! cutting oil can
and brush - knockout bar for head-stock IN GENERAL, I've always
found having a large decimal equivalents chart behind the lathe a
time-saver. Also a wooden sliding tray that is tip-proof and has a
small shelf sitting on the right-end of the lathe. A piece of white
cardboard is good to have for sighting down at tooling. By putting a
white surface under the bed, I can see the tool profile in prox. of
the work. Ron
(2213) |
| I'll add one more
thing to Ron's list. I'd make a wood plank with side rails to fit
over the bed of the lathe. Maybe a foot long. Place this over the
bed ways when you are changing chucks. It will protect the ways if
you drop the chuck. Yes, Ron the old style Rocker type tool holder
is referred to as Lantern type. I think this term is for the type
that reduces in diameter at the top by a radius. Tom (2214) |
| Ron, great
suggestions for tooling to keep by the lathe. I'm still getting
things organized in the shop (garage) and can't tell you how often I
go searching for the right wrench. I end up setting all that stuff
in the chip tray (very bad idea) and everything gets coated in crud.
I look forward to assembling exactly what you have described.
Paul R. (2216) |
| I saw in
Model Engineer Workshop I think, a neat idea for putting on and
taking chucks off. A wood block to fit the ways was machined to a
close fit to the bottom half of the chuck. A pair of metal fold down
handles were attached to pick it up and store it on its side in its
cradle. No more trying to hold the chuck up by hand or dropping it
on the ways and a neat way to store chucks. Walt (2223) |
| Best grinding
heels for HSS/Carbide Bits? |
| Anyone
have suggestions for preferred bench grinding wheels for shaping and
sharpening HSS cutters? Also, what grit sizes for roughing and
finishing? Can the same wheels be used for both carbide and HSS
cutters? The cheapo grinder I have seems to take forever to shape a
cutter. Gotta be a better way! Jim
(2232) |
| Jim, I use a 60
grit wheel for grinding HHS toolbits, drills, cutoff blades etc.
with good results on my 6" bench grinder. I also have a small 3450
rpm motor with a homemade arbor on it to use a 3" by 1/4" 80 grit
wheel for small drills etc. There is a green wheel out there that
can be used on carbide for roughing, but the wheel wears more than
the tool you are grinding. I only use a diamond wheel for grinding
carbide then hone with a diamond hone. Joe (2235) |
| Indexable
tools? |
| What thoughts are
out there regarding indexable tooling? Specifically should I buy as
my first toolbits an indexable carbide set or the brazed carbide tip
sets? Advantages of each over long run? Tim Q
(2504) |
| My personal opinion
is based on my home-shop use. If you're making parts for a living,
you need different advice. Also, if you have modern machinery or 20
years of experience, get different advice. If you're also an
inexperienced home-shop person, then just buy cobalt steel blanks
and grind your own. I have all different types of tools available
and almost always use the cobalt blanks. One reason is that there is
no versatility in either indexable or brazed carbide bits. If you
need something odd, you can make it from cobalt or HSS. You can
grind your own brazed carbide but it takes forever, and costs much
more in the long run. Another reason that I shy away from index or
brazed tools is that they chip if you make any mistake, and once
they chip, they are hard to repair, often worthless. HSS and cobalt
are much more forgiving. Cobalt lasts longer than HSS, costs only
slightly more, and grinds just as easily. It's a win-win over HSS.
If you're doing outside threading, you may want to get a brazed
carbide threading tool. It's nice to have something with the perfect
form for this particular job. But use it carefully! They say that
imported brazed bits are much poorer quality carbide than quality
domestic brands. I've seen that, too. Some of the better carbide is
"micrograin" meaning that the carbide particles are finer and hold a
better edge longer. I bought a set of imported carbide-tipped boring
bars, cheap. It has been useful, but also frustrating. It's not that
the steel in the bar is bad. It flexes a little, but so what?
However, the tips are very brittle, dull, and poorly ground. To use
them, I have to fine-tune them for each cut on a green wheel. Most
of the time, however, they've allowed me to get the job done, so I
can't fault them too much. Carbide is a science all it's own. Lots
to learn. Here's some starting pages:
http://www.thegallos.com/carbide.htm
http://www.sccarb.com/ Bob
(2505) |
| Search the archives
a bit on this topic. I think that its been covered in bits and
pieces before (pun intended). I agree with Robert's reply. grinding
tool bits is the way to go. I would add that if you need guidance on
grinding bits, look for a reference. the Lindsay books reprints of
the 8 sb lathe booklets are good. I recall one was on grinding bits.
Otherwise, a good lathe or machining book will have what you need. I
think that it might be in the how to book too. When you get cobalt,
you can get either 5% or 10%. I have found 5% is fine. I differ a
bit on the carbide tipped bits. to really use the carbide tools
efficiently (take advantage of their properties), they want higher
feeds and heavier cuts. not something you are usually going to do by
'hand.' They have their place, but don't discount them. learn cutter
geometry and grinding before you play with them. You have to have a
feel for how the bits work before you realize the advantage of
carbides.. buy the name brand carbides when they are on sale, they
are not much more than regular priced imports. get the 60 degree for
threading, it saves time. the tipped bits come in different grades,
know what grade you are getting (they differ for cast iron,
non-ferrous, steel, etc...). I think that good carbide tipped bits
are handy to have around. I use them for that often unknown found
steel that I want to use that just chews up hss/cobalt bits. I use
them for threading too (alright I am lazy/impatient to fuss over the
perfect 60 degree). You could stand to get a left and a right swept
bit. I also use the carbide tipped bits in my flycutters. They seem
to hold up better. You do need a green wheel or diamond wheel to
dress them and touch them up. But again, you need to know how to
grind a bit. Other tips: dress your wheel! an import 1/4 diamond
mounted in a shank is cheap, get one. A dressed wheel cuts better
than an undressed one. Set your grinder up with some sort of guide
or rest to support the bit. Have a cup of clean water near to chill
the blank. An inexpensive flat stone/diamond knife sharpener is
handy to have too to hone and polish the edge. It does help more
than you realize to get that nice finish. dp
(2506) |
| Do you intend to
use the original (?) lantern style toolpost with Armstrong holders?
If so, learn to grind HSS or M2 toolbits. Once you can grind and
hone tools well, you can use the cobalt tool blanks for tough
materials. I wouldn't recommend high cobalt content bits until
you've worked out grinding pretty well. If you have a 4 way, block
style toolpost, or a quick change style, then you have a few other
considerations. If you intend to work mostly in aluminum, or in work
one inch diameter I'd suggest sticking with standard HSS or M2
toolbits ground to shape. If you intend to work mostly with larger
work in steel, carbide comes into its own. The lower cost of
indexable tooling that takes positive inserts (TPxx series) is
offset by the higher index costs. The toolholders you can make or
purchase from Plastools take TNxx series inserts, giving 6 tips per
insert, at a cost per insert of about a buck if you catch them on
sale from Travers. Carbide has to run fast, and doesn't like to take
fine scraping cuts. Don't get me wrong, I love carbide, but I make a
fair bit of repair parts and special tooling in fairly hard steels,
so carbide is really good for most of my work. I keep tools set up
with C2 and C6 TiN coated inserts for general shop work. For fine
work I often use HSS, and keep a set of standard profiles ground to
the correct geometries for steel, aluminum, and brass available.
Once you're grinding three or four tools, might as well grind a
dozen and have them on hand. I did a fairly long post about grinding
tools on the model engineering list a while back mostly related to
tip radius geometries, if you'd like I'll post it here or send it to
you off group. I've never liked brazed carbide tools, even the ISCAR
stuff. The added costs of setting up to grind carbide well just
isn't worth it to me. I also get better results with toolbits I've
ground to match the material than with the zero top rake brazed
carbide tooling. The front clearance angle of the brazed tooling I
have does not work well in a lantern style toolholder. It's cheaper
to buy brazed bits initially, if you get a good deal on a bag of
tools at a show or on eBay, but the long term cost gets you in the
end. I bought about 50 ISCAR brazed toolbits for $10 at a show, new
and still dipped. These get used for roughing, when they dull I toss
them. Great for weird ugly scrap yard stuff, but not the way to go
as your only tooling. A Plastools holder will cost you $40 or so,
but 20 inserts on sale from Travers is only $25 or so. You end up
with a rigid toolholder and 60 tips for about $65. The cheap
positive rake insert toolholder are 5 for $40 or so, but good insert
run $6 or more each. You end up spending $100 for 30 tips. If you go
with indexed tooling, stick with half inch toolholders. This will
preclude packing a lantern post on a SB9, as these lanterns take 3/8
tooling, so you'll have to make a toolholder anyway. Stan (2510) |
| Stan, I would
really like a copy of that sharpening post. You could send it off
list, if you would?
Dee (2511) |
| Stan: how about
posting this to the files section of this group? I'd sure like to
read it! Pete (2514) |
| Does the holder have a pocket in it that has the same angle
as the insert clearance angle? (believe it or not one has a 90*
pocket that they put a 11* insert on) What material is the holder
made out of? Is the screw common? I'm not trying to scare you away
from the kit idea, Just trying to tell you there are some pretty bad
kits out there. I agree with buying high speed steel toolbits to
learn how to sharpen with. You can also find some already profiled
to look at. As a manufacturer of high speed steel throwaway inserts
and toolbits www.arwarnerco.com I'm partial to the high speed steel
anyway. Watch buying high speed mail order. A lot of companies list
there grade as 5% cobalt OR high speed. There are at least 5 grades
of high speed steel that have 5% cobalt. Stick with M-2, M-42 or
T-15. M-2 is for general machining and is the most economical high
speed steel. M-42 (8% cobalt) takes more heat and will wear a lot
longer than M-2.T-15 is like the ultimate. It's pretty tough But
will last the longest between sharpening.T-15 is also the hardest to
re-sharpen. Just take your time, go slow and don't burn it. All of our
kits come with T-15 inserts. Once they get dull you can re-sharpen
them also. Mike
(2516) |
| For what I do,
which is mostly aluminum and mild steel and tool steel and plastic
and brass, no exotic titanium alloys or the like [at least not on
purpose], I have found indexable carbides to be more of a pain than
they're worth. With HSS or with brazed carbides I can grind to any
radius/rake/clearance [and set the rocker toolpost to whatever
angle] appropriate for the job at hand...and I can touch up with a
stone to keep the edge and I can regrind for the next job. Recently
I had a piece of unidentified nonmagnetic scrap steel I was trying
to turn; this stuff is so hard it wiped the edge right off the
carbide insert, didn't shatter it, just wiped it off...and after
annealing it it was still better than file-hard. Even an alumina
grinding wheel has a hard time touching it. My green wheel will cut
it some, but at great expense to the wheel. That piece of barstock
is now my grinding-wheel dresser. With a HSS bit I could have just
reground it, with the carbide insert that's 4 bucks worth of carbide
gone. Also since my lathe is flat-belt drive and stalls if I try to
go too heavy or too fast, it's very forgiving that way, too
forgiving sometimes, with a HSS bit no biggie...but stall an
indexable carbide and there's that brittle 'SNAP' that is the sound
of another 4 bucks. IMHO indexable carbides are for production
tooling where it's the same setup, the same material and the same
cut over and over.
(2523) |
| What speed and
hp grinder to use? |
| What is the recommended speed for a grinding wheel when sharpening
HSS bits? and what horsepower grinder is most capable of delivering
it with the least effort? Harbor Freight sells a 3/4 hp 10" grinder
capable of a constant 3450 rpm. I also do woodcarving, and this is waaay too fast for gouges and chisels. Does the same apply for lathe
cutting bits? Only reason I'm asking this question now is I've never
had a need to grind my own bits until now. Previous owner left about
200 bits of various shapes and sizes. Bilal (3584) |
| Bilal,
I use a 3450 RPM 1 HP 8 inch grinder for almost all lathe bit
grinding. There are (at least) 2 schools of thought: The first is
hot grinding. Grab the bit in vise grips and hog it out. Ignore the
grinding heat. Just NEVER quench. You'll get surface microcracks for
a few thou into the bit. Do a nice gentle finish grind to get down
to good metal. Yes, it makes a person used to slow grinding carving
and woodworking tools cringe. It also works just fine. School 2 is
more traditional, hand hold, gentle pressure, dip in water, take
forever to grind a simple profile. I'm all in favor of hogging out
the basic profile as fast as you can, let the cutter air cool, then
do the final grind fairly fast, but not allowing to cutter to get
silly hot. The final grind removes the metal damaged by the heavy
profile grind. All of this assumes you are talking HSS, M2, 5 or 10
percent cobalt, i.e. conventional modern toolbits. If you are using
a hardening (high carbon) tool steel for form cutters and the like,
then go the gentle route, these steels really don't like being
burned, and tend to have the heat damaged zone go deeper into the
work. Whenever possible, I cut rather than grind the basic profile
for form tools. If you look at the heat treat and hardening cycles
of HSS, this starts to make sense. These materials require
completely different treatment than a carbon steel, so the rules for
grinding carbon steel items such as traditional woodworkers plane
irons and chisels really don't apply. Keep in mind that grinding
wheels are cutting tools, just like sandpaper, or a blade. If you
aren't cutting, you're burnishing, and clogging the wheel. Stan
(3588) |
| Cutting tool
material |
| Lew; If you are
willing to take the time to learn to grind your own tools, M2 HSS
blanks are a good place to start. It takes maybe an hour or less of
playing around on a grinder to sort out the grinding of tools. The
best introduction to grinding tools I've ever seen can be found at:
http://www.sherline.com/grinding.htm While this is the Sherline
site, the only better intro I could think of would be to hang out
with someone who is good at grinding tools and having them show you
the tricks. After you've digested this page, there is a file in this
groups file section I put up a while ago, it's called
stantoolgrinding.txt. It's an edited and cleaned up post of a reply
to a guy on the model engineering mail list regarding tip radius
considerations, with a bit of general tool grinding info included.
Don't bother reading my file until you've read the Sherline page -
some of it just won't make sense until you've got a handle on the
basic grinding process. I'd recommend using M2 blanks for a while,
once you've sorted out the grinding you can take on the high cobalt
blanks, they can take a bit more work to grind. For the materials
you specify, M2 is plenty good, the extra edge retention of higher
cobalt content bits comes into it's own only when you are turning
hard materials, or doing nasty intermittent cuts on welded
assemblies - not a fun task, and certainly not a good place to start
out. Brass likes zero top rake, aluminum cuts better with lots (15
degrees or so) of top rake, steels do well with around 5 to 7
degrees of top rake. Carbide is good, but unless you have a grinder
that can do carbide, you're out of luck for any special shapes. The
cheap no-name brazed carbide tools have never pleased me, in fact I
have a bunch of Iscar bits bought in a lot and even they don't give
the finish I desire. I usually have a plastools toolholder
www.plastools.com
mounted for general work, which while more expensive than the insert
toolholders that take positive rake inserts, uses negative rake
inserts (LOTS cheaper, 6 tips per insert, very rigid toolholder)
tilted 5 degrees down towards the tip to give clearance. You have to
have a fairly well adjusted lathe to handle the heavier cutting
stresses. I usually finish cut with either a ground HSS bit or a
positive rake carbide insert. Be aware that most toolholders for
carbide expect to present the tip to the work straight on, rather
than at the angle Armstrong (lantern) style toolholders tend to work
at. You can grind HSS to use a lantern toolpost if you prefer or
only have this style of toolpost available. If you intend to use a
lantern toolpost and Armstrong toolholders, the grind geometry will
be different. Basically, you grind NO top rake, around 15 degrees
front clearance, and 7 degrees side clearance, assuming a toolholder
that presents the bit tilted up around 7 degrees. For threading or
brass, you grind a -7 degree top rake. When mounted this ends up
giving a zero degree top rake, just what you want. South Bends "How
to Run a Lathe", available from Lindsay and others, covers grinding
tools for lantern toolpost use. I've made block style toolholders
for the 9 inch lathe that take 1/4 inch bits in a 4 way setup, and
other ones that take 2 half inch tools or a half inch tool and a
boring bar. You can make these with just a lathe, but a mill sure
makes it a lot easier. One option I haven't mentioned is the insert
tools that take HSS inserts. Several folks have commented favorably
on these. I have never used these, as I grind bits regularly and
stock carbide tips in several grades and geometries, so I haven't
felt any need to try these out. Others may say they're the greatest
thing since sliced bread, and they may well be right. The holders
and tips that were displayed at Cabin Fever certainly looked good,
and the folks selling them seemed to be good folks. Hopefully this
answers some of your questions without dumping too much on you all
at once. Lots to learn, leaving metalworking books in the bathroom
tends to allow you to read a bit, then think a bit between visits. Stan
(4920) |
| Stan Lots to
digest, but looks like GREAT info. I have a tool grinder and an
Aloris toolpost; didn't t even get a lantern post with the lathe. Your
good info gives me LOTS to work with! Lew (4921) |
| Lew, I
ground my tool bits for many years but still do on occasion. I went
to 5/16" Kennametal tool holders that accepts T221S inserts. The
difference in time saved and using a ultra sharp tool all the time
will amaze you. You can buy these triangular inserts in any grade
you want. Kennametal will also mail you a catalog if you request
one. Also if you watch e-bay they go very cheap sometimes. If your
interested, give me a shout and I will give you the numbers of my
tool holders. Each insert cost me about $10.60 CDN from Kennametal.
I use my lathe every day and at times long hours. I go through
around 10 to 15 inserts a year. Small price for the time saved on
the grinder. Barrie
(4924) |
| I like 5 to 10%
cobalt they hold up better. As for carbide use inserts and get the
best you can afford. We use valinite at work and I won't use
anything else. cnmg and tnmg in the 332 and 331 size is all we use
for general work. Kerry
(4937) |
| Cutting Tool
Sources? |
| Can anyone
recommend a mail-order source for cutting tool stock, and/ or precut
cutting tools? Andy (6326) |
| Lots of good
sources; Enco: www.use-enco.com J L Industrial:
www.jlindustrial.com
McMaster-Carr: www.mcmaster.com Plus many others, I'm sure. Jeff (6328) |
| Andy
try, 1-800-645-7270 or, www.mscdirect.com (6334) |
| What Lathe Bits
Do You Use? |
| I need to get
tooled up and all I have are 15 lbs of misc bits that came with some
other tooling I bought. What do you all recommend- HSS, Brazed,
Carbide indexable, Chinese, USA? I've seen a wide variety on eBay
and harbor freight, but I'm a little spooked by some of the junk
I've rec'd in the past. (7275) |
| There is a
good book printed by South Bend (how to run a lathe) that has
excellent instructions oh how to grind your own bits. The type of
material the bits are made of really depends on what you are going
to be cutting. Just get yourself some raw bits a grinder and a can of
water ( for quenching) and experiment. Mike (7279) |
| It sort of depends
on what toolholders or toolpost setup you have. If you have a
lantern toolpost and only toolholders that take 1/4 inch bits and
present the cutters tilted upwards, you are pretty much stuck
grinding 1/4 inch tool blanks to form or finding something close to
what you need amongst the 15 lbs of tooling. Assuming a lantern
toolpost, you can always flip over the concave washer, add some
packing under any tool that fits the lantern post slot, and go from
there. You may have a hard time getting enough clearance for some
tasks, but a lot can be done this way. You CAN use the lantern post
in conjunction with some packing under a 1/2 inch bit (HSS, brazed,
indexed carbide, whatever suits you) on one side of the post,
packing on the other side, and a 3/8 toolbit or bit of stock through
the lantern post itself. Makes a usable strongback sort of clamp. If
you have a toolpost set up to handle just about anything (4 way
toolblock or QCTP, doesn't really matter in terms of what tools you
can use) then I usually use indexed carbide insert tooling. Brass
gets done with tools ground with no top rake, aluminum gets done
with either the indexed tooling or with HSS or better tools ground
with sharper angles. Block style tool holders are fairly easy to
make, just a block turned flat on the side that goes down, a few
slots to take tool bits and set the point on or just below
centerline (so you can pack them up onto center), a few holes, a bit
of tapping, and it's pretty much done. You can make them fancier, or
easier if you have a mill or access to one, but perfectly workable
ones can be made with just a lathe. I've never been pleased with the
results from the brazed carbide tools I've used, ISCAR or Chinese
bargain basement stuff. Chinese HSS blanks vary from very nice to
not so hot, but are usually OK. USA or UK tool blanks (M2 or better)
are almost always good, no doubt there are blanks from many other
countries that are good, just haven't used them myself. Check out
Sherline site if you haven't ground lathe tools, they have about
the best pragmatic intro I've seen, no heavy theory, no dogmatic one
and only one way attitude about stuff that really doesn't much
matter if you are off by a degree or two. Quick and dirty guide and
tips: Front and side clearance 7 degrees, back and side rake 0 for
brass, around 5 to 8 degrees for steel, around 12 to 15 degrees for
aluminum. Tip radius can be anything from slightly rounded up to the
point you have an almost round nosed tool for finishing cuts. Yes,
this is oversimplified, particularly in terms of tip radius, but
gives you some starting point. Play around with a grinder for an
hour or so and you'll find what works with your equipment. Tight
unworn lathes with spindle bearing adjusted correctly can handle
more cutting force without chatter than a loose lathe. Carbide works
best when cutting hard - if the chips aren't blue you're moving too
slow. HSS can take super fine cuts just fine, if you take the time
to stone the edges and don't try to use a finishing tool straight
from the grinder. Stan (7280) |
| Cutoff tool use |
| I use mostly brass
and have discovered that it cuts much better at higher speeds. Just a
little top rake; tool dead center. I don't need any oil - it cuts
like butter. If it digs in, then lower the tool slightly. I use as
little clearance as possible. Used to cut with back gears, but no
longer. Steel still gives me fits and aluminum I find very difficult
unless I use kerosene as lubricant Frank
(8393) |
| Concerning cut off:
My 94 year-old neighbor and friend, a retired tool and die maker
and shop owner during WW II and after here in town, tells me--when
he interviewed a prospective "machinist" for a job his first
requirement was for the prospect to demonstrate cutting-off a piece
of cold rolled steel. If he couldn't do it, the interview was over.
No questions asked! Neil (8397) |
| That's a bit like a
story I heard about a machinist gunsmith in England. They said he
would give the prospective employee 2 days to make a one inch square
cube. All measurements had to equal 1" exactly. The story goes that
only three men ever could do it and were hired and worked for him
till the end.
(8423) |
| Spherical
Turning tool |
| Spherical Turning
tool I'm making that will fit all 4 of my lathes by changing out
the base plate and a pic of my QC Tool Post
http://tejasdragon.com/Today.html
The Wood Dragon (8962) |
| Spherical Tool
Update - I works there's some more pics of the tool on the 7x10 this
weekend I'll make the adapter for the SB9. Just made the first test
cuts in SS works great. Just have to do some minor finish up on it.
The Pics are at http://tejasdragon.com/Today.html The Wood
Dragon (8969) |
| Tool Bits ?
|
| Can
anyone help me with grinding tool bits? I am new to this and need
better pictures of what tools should look like I am just wondering
if anyone has anything like this? Frank
(10032) |
| Frank
http://www.sherline.com/grinding.htm
This is pretty good IMHO. dee (10034) |
| Some good info on
this US Army link re tool grinding..
http://155.217.58.58/cgi-bin/atdl.dll/tc/9-524/toc.htm
Len (10035) |
| Cut off tools |
| I will try to
answer the last three post without posting three separate
messages.1;I just have the regular tool post that came with the
lathe and can't afford one of the Aloris type tool holders.2;I am
cutting only about .50 from the chuck jaws. and 3;haven't tried
using the tailstock center when cutting off. Also I don't like the
idea of trying to cut off material with a hacksaw while the lathe is
running. So what am I doing wrong? Bill C.(10505) |
| Bill, I don't think that you are doing anything wrong. My
experience has always been bad with lantern type toolposts and cut
off tools. If tightening everything up and following the advice in
the above posts doesn't work, get used to using a hacksaw. I don't
like to recommend that, but it works, just be careful. ken
(10506) |
| What material are
you cutting? Parting, using a lantern holder, is like Zen.
Enlightenment strikes if you keep trying. I don't think you said how
fast you were turning the stock. Try changing that. I used to have
trouble until I began to part at normal fpm rates. Make certain the
cutting tip of the tool is really sharp and not rounded. Try it
completely horizontal and a tad (just a wee mite) below center. That
way it will act as a scraper and if your work doesn't climb, then
you can try one thing at a time: raise it to center, change the
clearance angle (advantage of a lantern holder is that you can make
these minor adjustments) At some point you will find a combo that
will work. But what are you trying to cut? Frank
(10515) |
| Frank. I am
cutting 4140 at .50 dia and using third speed. I'm going to fix the
problem as soon as I can afford to get the T slot cross-slide
casting. I have to rake up some money so I can order it. Bill C.
(10516) |
| What material are
you cutting? Parting, using a lantern holder, is like Zen.
Enlightenment strikes if you keep trying.######## Although the above
sounds bizarre its actually not far from the truth. It takes an
extended amount of time to learn to do parting off. Moreover, it
almost seems that its not something that comes from repeated
practice at one sitting. The only hint I have is that on deep
plunges, the binding is caused by the sides not the front of the
blade (from my experience). Cutting fluid is of little help with
aluminum but I find oil works on the side sticking even when parting
aluminum I would note that the original poster is possibly
misinformed regarding tool holders. The Phase II holder that I use
on my SB9 was a comparatively cheap 95.00 and comes with a cut off
attachment. (10517) |
| Dr.$95.00
might be a drop in the bucket for you, but I can't afford anything
like that. I usually don't have that kind of pocket change to
spend. Bill C.
(10521) |
| Bill, Unless you
require the T slot cross slide for milling and do a LOT of parting,
it would be my humble opinion that a $190.00 (not the lower quality
button, but the MUCH stronger wedge style) tool post would be a
better investment. yeah, tooling will cost more than you paid for
your lathe. I got an old 9' a for $325 and have twice that in actual
tooling costs and probably 10x that if I bought the stuff new.
Dave (10523) |
| Bill, I concur
with the previous poster about QC Toolpost vs. "T" slot cross slide.
I have done a lot of parting with the lantern type tool post before
moving-up to a 4 position tool post and then an Aloris. I too have a
limited budget for tooling and it was many years before I could get
an Aloris but I am so glad I did. It is a BIG improvement in
rigidity and lowers the frustration level. My experience in using
the old Armstrong tool holders is similar to others that have posted
here. What I can say is: 1) Make sure the cut off blade is SQUARE
(perpendicular) to the work. Use a dial indicator on the side of the
blade and traverse the tool in-and-out to check. 2) Make sure the
cutter is ON-CENTER. Use the pocket ruler test to check (that's when
you place your 6 inch flexible rule between the cutting tool and the
stock to be cut; bringing them together so that the rule is pinched
between them. If the ruler stands straight up, you're cutting blade
is on center). 3) Make sure it is SHARP! Others have covered this in
more detail and it would be redundant for me to do it again. The use
of back rake is a debate between experience machinist and can be
dependent on the characteristics of the material being cut and the
preferences of the user. 4) Make sure to use CUTTING OIL when
cutting steel. Sulfurized thread cutting oil sold in hardware stores
works pretty well. Also, bacon grease (lard) will work well but the
smell will make you hungry. Use a cheap brush to apply or rig up a
can (like an old style oil can placed up-side-down with the bottom
cut out) on a stand so that it drips in the kerf of the cut. I used
a pencil in the hole to regulate the drip rate. Just make sure that
plenty of oil is getting in there. 5) Make sure you are NOT trying
to CUT TO FAST. Start off slow and move up if you need to. I would
say the slowest direct drive speed would about right for the 1/2"
diameter and material you mentioned to start. When you gain more
experience you can experiment with speeds. 6) Lastly, PERSISTENCE!
If it doesn't work, check everything again. Most problems can be
traced to dull or improper sharpening of the cutter or the set-up is
improper. Webb
(10527) |
| Cutter size |
| Well since were
talking about a HSS cutter it will be more ridged, absorb more heat
and take longer to burn up, also has more shock resistance in
interrupted cuts. A 1/2" tool is a bit big for a 9" machine but that
being said I have more 1/2" cutters then any other size and use them
the most. Kerry (11415) |
| I have everything from 3/16 to 3/4 as long as it will fit
my tool holders, I'll use it. 1/4 is a breeze to grind. and if you
are cutting hard stuff, the super high quality bits cost less, and
since you cannot take deep cuts, you can often hold them short or
support underneath. I have one 1/4 that is ground about half the
length and I use it for a small boring bar. the larger you go, the
stiffer you get and also the more heat sink if the tip is getting
hot. Dave
(11430) |
| When I was in trade
school they gave us 3/8 tool bits and we had to grind our own.
They're about the smallest I use although I do have 5/16 and 1/4
too. since you will be getting new ones I'd get the 5 to 10% cobalt
they last a lot long then plain M2 HSS or get M42 HSS it's better
then M2 for hot work strength and shock resistance. and you will
find the you can get a sharper tool with HSS then carbide makes a
big difference on aluminum and 1018 CRS. Kerry it. Now I'd stock up.
really do Larry
(11449) |
| When I set up our
CNC lathe at work to drill for a 1/2 13 threaded hole in titanium
Cobalt drills 10% were the only ones reasonably priced that would
hold up. Even had a tool supplier come out and try to sell us a
carbide insert drill with through the tool coolant. we broke it on
the second part. My cobalts were getting 80 pieces per drill .437"
in titanium with no pilot hole. That cobalt is good stuff.
Kerry (11462) |
| This thread kinda went off size into metals. I use cobalt as the minimum, and
was lucky enough to have found a few Tangtung bits and some REX95
bits. seems MoMAx cobalt bits are pretty common in the used tool
bins so that is where I settle on my purchases. does anybody have
any comments on REX95 or Tangtung ? I have found some references on
the net, but no real comparison tables to say what is so much better
than others. on another note, my Kennametal booklet has a selection
triangle with edge wear in one corner, shock resistance in another
and crater resistance in yet another corner. so the three criteria
seem to be impact from interrupted cuts, abrasion from metals on the
edge and abrasion on the top of the tool. Dave (11487) |
| Tooling
info/advice |
| I need to buy some
tools for my SBL Workshop 9B, I have none at all. It has a QC
toolpost that takes 1/2in. square shank tooling. The usual selection
of facing/turning tools are available as either standard HSS or
indexable replicable carbide tips. Question is what type of tools to
buy. Also what size shank for the 13mm tool holder? Do I buy half
inch so they fit snugly in the toolpost nip up with Allen screws or
go for a smaller shank i.e. 10mm. My next query is about quality of
tooling, there is a fair price differential between Chinese copy
type indexable tooling the branded Sandvik/Glanz types. For a newbie
is the extra cost worth it? Also there is a large price difference
between centers. Seems, hardened centers are fairly inexpensive,
carbide tipped ones are roughly twice the cost. What's the story
here, please. Basically my question is, what is the best balance for
a first timer. Best quality but only a few tools at first, or a full
set of cheaper (Chinese copy) tooling? Jon
(11924) |
| Jon, I'd probably
get 1/2 shank. Still, that shouldn't make a big difference. There
are companies sell tooling make in Poland or eastern Europe. I do
have Boring Bars of this origin. They are of good quality. I also
have some micrometers form these countries. They are much better
than the Chinese ones. They are very close to top US brands. I am
not sure if they make regular square shank tooling though. I have
only looked at boring bars. It seems you are on the other side of
the pond. Your offerings might be better or worse. I like indexable
tooling. Still inserts can cost $5-10 each. Some places sell them
individually others by the box. Still, its nice to have HSS around
thoug I think there is a bit more of a learning curve due to having
to grind them. I think just the hardened centers will do you well.
Maybe look at live centers instead of the carbide tipped ones.
Tom (11926) |
| Jon, I use 1/4 and
3/8 cutters with my 9". You'll find out the difference when you try
to grind them. I/2 takes a LOT of grinding. All I've ever used are
HSS and cobalt. You can put a nice edge on the simple cutters.
Carbide I have no way of sharpening. I think others will agree that
HSS will take a thinner slice off. IMHO these small lathes don't
have the horsepower to take advantage of deep cuts. Carbide is great
for production and the larger cutters will displace heat better. I
doubt that you'll need these qualities 1/4 cutters are inexpensive,
get a doz. or so to learn on. You already have a good start with a
QC toolpost. That's a nice feature. For centers. dead centers will
work fine while you learn. Probably been used in shops for the last
hundred years or so. I like the carbide tipped ones. Although I've
played with the idea of a live center a few times. Live centers are
great for heavy stock and deep stock. I seldom do either. Hope this
helps some. I'm a beginner too and opinions vary. Larry
(11935) |
| As far as centers
go I prefer a liver center over the dead center in the tail stock,
but both are fine just remember to put never-seize on the tip of the
dead center to keep from building heat up and damaging the tip, I
personally don't think that a carbide tipped dead center is worth
the extra money over a hardened dead center, at that point buy a
live center and forget it. As far as HSS or carbide they both have
there purposes, on Brass and Aluminum and most non ferrous materials
I always use HSS, because the material usually dictates it to get a
good finish, especially when it is small in diameter. Carbide will
part stuff just as thin in steel as HSS but you need a green
carborundum wheel on your grinder or a diamond wheel to get it
finished real well. Carbide has the advantage that you can cut and
cut with it compared to HSS without oil or coolant with little or no
damage. For the home hobbyist the expensive Valenite and Sandvik and
others are not really justifiable because of the cost. I machine
most of the things I make in tool steel and carbide is almost a must
just for tool life. As far as the size goes use what's affordable and
what you can get easily and sharpen easily, most of my HSS is
Latrobe and Rex 99, for carbide I try to get micro grain in AR8 AL8
tool bits in a 3/8 or 5/16 blank. I am a tool moldmaker by trade and
have been building molds and running Lathes, Mills, grinders and EDM
machines for 22 years and have also done alot of CNC programming in
the last 6 years along with CAD designing my own molds for a family
business. The best way to learn is to ask old timers how they did it
and then apply that knowledge with more modern techniques and do the
hands on learning thing. It is sad to see that building Dies and
Molds is a dying art because the younger generation is being taught
that a CNC is the best way to do everything, this just isn't true,
the old ways are still very valuable so find an old toolmaker and
talk to them as much as possible.
(11936) |
| I'll second that! My company has an acre
of CNC mills, etc., plus dozens of lathes and Bridgeports. Anything I
need to know, I can find out at coffee break. How to grind a tool
for copper? No problem, they show me a handful. How to grind and
relieve and set a cutoff tool? Here! I work for R D. A lot of the R
D people just throw a print at the old pro machinists and then beat
on them to get it done, but me, they like. They know I have a lathe
and a miller at home, and one of them gave me a big
compliment..."He's a chemist who found out too late that he would
rather have been a machinist!" Also, of course, they do better work
for me, and faster. Because they take pride in their work, and want
to show me how a REAL machinist does it. The crudest quick fixture
sketch comes out with 20 micron finishes). In my place there are
probably 800 or 900 man-years of machining experience. I'd have to
be a fool not to ask these guys questions, no matter how off the
wall. Today's was, "I am turning chrome/cobalt /5% moly. What shape
tool are you guys using here to do facing?" It's like having the
Library of Congress. No matter what screwball material I run into,
one of these guys has made a few thousand parts out of it. including
stuff I would not touch, like beryllium and depleted uranium. ("Oh,
that stuff...Machines like unhardened 4140")
(11946) |
| Right on the money.
If we don't pass on what we know it will be lost and some poor fool
will have to figure it out all over again. Now how are you going to
get any real work done doing that. I get as much info as I can from
the machinists around me. it's the only way to learn. Kerry (11948) |
| About turning
tool inserts |
| I relearned a good
lesson today. First, thanks to the poster last week who suggested
Carbide Depot! A year or two ago I bought a set of insert tool
holders at Wholesale Tool, near me. I was pretty unimpressed with
the inserts that came with them. I ordered some cheap ones from MSC,
and they were OK, but I found myself grinding brazed carbide tools
and using the insert holders less and less. They never stood up
well, the edges were fragile, etc. But I saw some Toshiba Tungalloy
at a low price at the Carbide Depot and tried them tonight on a
number of metals, before I went to the piece I had to machine. The
piece was 6-4 titanium, and I had a lot of metal to remove. Well. I
see I have to rethink this. It cut like 303 (Soap, basically!) with
these inserts...NO COOLANT. The first thing I noticed was the
finish. they were polished. Some of the cheap ones I had bought
before were TiN coated...but as we learn from buying cheap Far East
end mills coated with TiN, you could TiN coat SH7T if the price were
right. So here we are again with a lesson that has been shouted at
me a million times: "If you pay half the price, for a tool that
wears out ten times as fast, the cheap one costs five times as much
as the expensive one." There are times saving money is not just bad
math, it's stupid. And this is one of those times! Why, I did not
even pay that much for these Toshiba inserts, anyway, at Carbide
Depot. At least, for once, I know who made these. (11971) |
| Help with
brazed on Chinese carbide tools |
| I have some brazed
on Chicom carbide tools in both C2 and C6 but I can't turn well with
them. I used them in a tool holder that is straight, i.e., has no
built in rake like the SB tool holders. Using HSS tools that I've
ground myself (and I'm no machinist) I have no problem and turn
clean and smooth. The materials I've tried to turn were both hot and
cold rolled steel of unknown composition. I turned at high speed
with low feed rate taking cuts around 30 mils both dry and with
"milk." Any ideas on what I might be doing wrong? I want to master
the carbide tools so I can go for some indexable carbide tooling.
John
(12312) |
| John, I have
used both Chinese and "Good" carbide tools n my S.B. with good
results. You may just have to experiment with wiggling the angle of
attack of the tool. Carbide is great for turning cast iron where
there may be some residual sand and junk from the casting. Mike (12318) |
| John, I've never
gotten good results with brazed carbide, PRC or ISCAR. No top rake,
no chipbreaker. I do get good results using both positive rake insert
tooling and the Plastools holder which tilts TNMx series inserts
down 5 degrees to "fake" a positive rake. I got a bag of ISCAR
brazed insert toolbits for a song at a flea market, and have found
they are good for peeling off mill scale or the surface of castings,
but that's about it. Stan (12321) |
| John: Carbide
works best at speeds faster than a Southbend can go. If you can not
adjust the rake, use the carbide for rough cutting and the HSS for
finish cuts. If you buy inserts get the TiN coated inserts. Also
consider buying an Aloris No. 16 holder, it takes two inserts and
gives you both RH, ans LH. Gary P. (12324) |
| Gary, an
Aloris clone has been on my wish list for a while, maybe I'll have
to move it to the top along with the Aloris #16. I've had really
good results using carbide tooling on my RF31 and had high hopes for
the SB. The speed must be the difference. John (12325) |
| Carbide
inserts vs grinding your own bits |
| For
someone new to lathe tooling and operation, not taking into account
the cost factors what do you think is the easiest to use, carbide
insert tooling or learning to grind your own HSS bits? Its seems to
me that the inserts are ready to go and start cutting, when its dull
just turn it around for a new cutting point. Grinding your own
cutting bits seem to be an art unto its own. I have enough to learn
with out having to facture in that my ground bit may be the problem
why I am having trouble getting the job done. Is the carbide insert
tool holders [Aloris] just that simple to put in an insert, set the
tool post angle and start cutting? Anyone have experience with doing
both and what would you start with if you had it to do over again?
Bill
(13397) |
| Bill, I use HSS
only. With the light work I do they suite me fine. Not too bad, I've
found grinding my own to be very forgiving. I tried a new borrowed
carbide cutter. I like mine better (better finish). Maybe if I was
cutting some high tech stuff of doing production work I'd feel
different. I really see no reason to change right now, I'm also
kinda new myself and "may" in the future be able to appreciate
carbide, but not now. Buy yourself a handful and go to town. BTW the
latest copy of 'Home Shop Machinist' has a nice article on
estimating angles on grinders. Start with 1/4 inch cutters, repeat,
start with 1/4 inch cutters. MUCH easier to learn on and cheap.
Larry
(13398) |
| Bill, I'm still a
newbie, as I went back to school to start learning this in 1998. I
fussed under my breath at the instructor for having those dandy
carbide bits there in the tool crib and making us grind so many
failures to try and cut with. Now, I have a fair number of carbide
tools, both brazed and indexable, and make good use of them.
However, I cut a lot of oddball shapes that I have to grind from HSS
blanks, because carbide just don't come in the proper shape. Also,
alot of stuff has interrupted cuts, and carbide just plain don't like
"cuttus interuptus". I'm really grateful that I had to learn it
first. Johnny (13399) |
| Start with HSS. personally, I like cobalt for a longer
edge. learn to grind and you get the option for any shape you might
want. use inserts and you may never learn to grind a tool. Carbide
requires a deeper cut and a heaver feed so you will break tiny
parts. I needed a 0.04 pin and using HSS was the easy way. carbide
will chip or shatter on interrupted cuts like a shaft with a keyway.
HSS is much more forgiving. Carbide is great for production work,
they index within a few tenths or better. a TPU has an un-ground
edge and a TPG has a ground edge and costs more, but will take a
shallow cut better. by the time you learn the nuances of the tooling
you will spend some bucks. I got some mystery metal, turned out to
be a case hardened pin, 1.5 in dia. the case hardening was almost
1/4 deep an only carbide would handle the cuts. If you can get the
insertable tooling, for a good price, get it. use both and you will
probably use both. I use a very high rake in aluminum and can't get
cheap inserts with a high rake. that means HSS and grinding. Also,
you can get a knife edge in a grind that you can't get on carbide. I
have never looked to carbide for threading tools as grinding is much
less expensive. I'm sure I could think of more is it was not so
late. bottom line is get both if you can, but get HSS if you have
one choice. HSS boring tools are also much less expensive especially
in long or tiny bores. Dave (13400) |
| Or you may just walk away from the lathe
for good, if you have to do a lot of copper. Nothing beats a hooked
HS tool for copper. See for yourself...
http://www.gearloose.com/CU.html
I use inserts for only two situations. One is machining in
production for one of the parts I make where I need longer tool wear
and where I do not want to take a minute to grind a tool...and even
at that, to get the finish I need I have to diamond-lap the top and
bottom surfaces of a RNL insert. This gets into the whole
philosophical objections to paying six dollars each for something
that needs sharpening. I use TNMG inserts for titanium. Other than
that' it's cobalt or HS.
(13402) |
| Griding
lathe bits on HF carbide tool grinder? |
| I'll admit it right
off the bat - I'm not the sharpest tool in the shed ;). I especially
have trouble thinking in 3 dimensions. I'm the type that has to turn
the picture of the tool bit the same way as the one I'm holding in
order to get the angle right... Anyway, I got one of the HF carbide
tool grinders today (nice sale: $129.95). I thought that the tilting
tables and miter gage would make it so simple that even I could do
it. BZZZTT - Wrong! Getting the end cutting edge and the end relief
angle is pretty easy. I tilt the table down at the angle I want the
end relief angle to be and set the miter gage to the desired end
cutting edge angle and push the front of the tool into the side of
the wheel. I can't figure out anything after that! It seems that I
need to have a slot for the miter gage that is perpendicular to the
side of the wheel (actually four of them). The only way I could
figure to do the side cutting edge angle was to use the miter gage
and do it on the outer edge of the wheel. Problem is, I'm hitting
the wheel below the center line and my side relief angle is wrong.
Hope I explained this in a way that is understandable. If anyone can
give me some pointers (pics would be great!).
Wallace
(13670) |
| There are some
pretty good details in some of the articles stored here.
http://groups.yahoo.com/group/mwhints3/files/ToolSharp/
JWE (13674) |
| Cutter for
graphite? |
| Larry: Graphite
cuts really easy, grind tools like for steel, really sharp, hone for
good edge. take really light cuts. Wayne(15551) |
| I made a few
graphite pistons and it seemed that just about any good metal
cutting tool with a nice smooth radius on the tip will do.. Use fine
feed and light cuts. Also use copious amt of any liquid lube to
entrap the swarf which comes off as a fine powder that goes all
over. The liquid turns it to mud which can fall on paper towels
newspaper etc protecting the lathe and its parts. I have some square
section graphite rods which turned well when held in my 4 jaw chuck.
If you should need a piece I'll send it to you if I have the right
size. ED (15556) |
| Larry When I made one of these, for a Jerry Howell
engine, I used a cutter to get close to the needed size then I
use some 2000 grit sandpaper in place of the cutter to finish it to
the proper fit. Actually, just plain paper will work fine.
Dave (15557) |
| I've cut graphite
for one of Jerry Howell's Miser Stirling engines. As Wayne says it
cuts really easy. If you do mess it up, you can get graphite rods
from Rio Grande in Albuquerque. They sell stuff for jewelry
fabrication. Graphite rods are used to skim off the crud from the
top of a melt before pouring your investment casting flask.
www.riogrande.com Glen (15558) |
| Zen and The
Art of Grinding Lathe Bits |
| After months of
putting off trying to grind my own HSS bits, I decided today was the
day to grind a few. It turned out to be a very relaxing, fun and
gratifying experience. It's something one can screw up, then easily
correct for it and make it right. Not sure about other folks, but
when I'm building/repairing something (whether it's machining,
welding, or whatever) I kind of lose myself in it. This was what
happened while grinding the bits, thus the Subject line. I started
off making a round nose bit. Came out quite nice the first time, but
then I went back later and made it better (at least looking more
like the bits in "How to Run a Lathe". I then made a left hand side
tool and a left hand turning tool. I know they're not "exactly"
correct, but I think they'll cut just fine. I did get a brief (few
minute) instruction on how to grind my own bits while I was taking a
class in Alaska, but then when I got into the hobby in March 2003 I
was using only glued on carbide bits. I had bought blank bits to
try, but never took the time to grind them. I have to say that I'm
not real happy with the results of using the carbide bits; I'm
hoping the hss bits will do better. I think I'm now in the market
for a new bench grinder. My 8" bench grinder has a fine stone and a
wire wheel. I think I need another to give me a coarser wheel, and a
carbide wheel for when I do go back to the carbide bits. I did get a
utility sharpener from Sears
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yesvertical=TOOLpid=00921170000 ) for Christmas, but
found it quite useless for anything but dressing up the bits I'd
already ground. I think I'll be putting away my carbide bits and
concentrate on becoming more proficient at grinding my own HSS
bits. Dave
(15949) |
| I too have
experimented with grinding a couple of bits and found it pretty easy
and satisfying. I ground a little teeny 60 degree threading bit for
an internal threading bar - worked on stainless no problem. I think
sometimes people get too hung up on the theory and thinking each
angle has to be made with laser precision, instead of just having at
it and seeing what they come out with. After all, you'll never start
improving until you start DOING. Now too bad I have my grinder
mounted in the cold garage instead of the toasty basement. Maybe
it's time for the baldor after all. John (15951) |
| Kenny, The URL you
mentioned www.acc-finish.com doesn't seem to work. Would you mind
checking to see if something was mis-typed? Dave (15953) |
| Polishing the bits
with a Arkansas stone makes the bit give a nice finish. One trick I
learned on sharpening is to use a cloth wheel and Tripoli to polish
it. Have the motion of the buff go away from the cutting edge, bit
upside down. It works quicker than the Arkansas stone. Works great
on sharpening chisels and knives as well. JP (15966) |
| I was also
reluctant to grind my own bits, thinking that carbide was better
anyhow. Pfft. I was very happy when I ground my first bit and it
kicked the ass out of my indexable carbide bits in terms of finish
and accuracy on my small mini lathe. I do however love my carbide
boring tool. I cant wait to get my 9c going and taking the first cut
with it to experience how much better it is than my mini lathe.
(15969) |
| Finishing
tools |
| Can anyone give me the parameters for the fine finish tool
On what material, Steve? For most materials I seem to get the best
finish with a HSS tool shaped to cut from right to left moderate
front and side rake, small top rake and with the nose at about a
1/32 to 1/16 rounding. Set so the "trailing edge" of the tool is
almost in contact with the work as that seems to control the chip
better. Touch the very end with a stone to clean it up and smooth it
a bit. This is for steel and as I said in another post there are
steels and there are steels, some of the hardware stuff is terrible
to get a good finish. The rolling or however they make it wants to
tear, skip and everything bad. Get good free machining steel and
everything is different and better. Another thing that us amateurs
do that can result in poor finish is to try to sneak up on the final
dimension. Trying to take a cut of half thou or so will result in
poor finish. For brass just touch the top of the tool with a stone
to give 0 rake there. Aluminum (most of it anyway) can use more rake
on all faces.
(16869) |
| Most of the
hardware store steel is cold roll 'A36 steel' the same as angle
iron. Free machining steel contains lead like 12L14 and you can
produce a nice finish on it. 304 stainless finishes nicer than 316
for the same reason. JP (16875) |
| Cutting tools
stainless steel |
| What do you use for
cutting stainless steel? (17088) |
| I always use
Carbide brazed tip tooling unless a special shape is needed then its
HSS. It's more of how you cut it than what with. Which alloy are you
to cut? RichD (17089) |
| There are two
series of SS. The 300 series and the 400 series. 302 the most common
is easily handled with HSS. 400 is very difficult and requires
carbide. Jim B. (17096) |
| Cutter bit
gauge |
| I'm afraid I don't
remember the seller, but someone sells them occasionally on E-bay
(do a search under South Bend +lathe). I believe they're made of
laser cut stainless steel. The Buy-It-Now price is less than $20, if
I recall correctly. Dave
(17704) |
| That gauge is a SBL thing I know
someone who has one and he let me copy it. The angles are 10 and 12
degrees. I'm not sure but the gauges may have been promotional
handouts. They don't show in catalogs. Rob
(17706) |
| I bought one on
eBay at the end of Jan. Buy now Price: $11.99 (starting bid was
$6.99) Seller email: andrewbusic at yahoo.com Material: stainless
steel. It is a plate cut on a laser cutting machine. Cuts are clean
but need a little bit of honing. I have not used it yet but I am
happy about it. (lathe is not really set up) He sold his last gauges
on eBay about a month ago but mentioned he would do another batch.
There is also a reference to it in the book How to run a lathe by
South Bend. Angles are written in the book to my recall. Guy (17713) |
| Rob
They were in the old catalogs. I am looking at the 1956 catalog and
it is item CE2169 for a cost of 60 cents. It even had the South Bend
Logo on it. Some one should have bought some extra back then. You
could sell for a pretty good markup. (17730) |
| Who uses
indexable inserts |
| I have a heavy 10
South Bend lathe and been using the brazed carbide tipped cutting
tools. I'm wondering if indexable tools would be better and what
type to buy. I have a phase II tool holder with all the attachments.
Of couse I have and use regular HHS bit that I grind myself also.
I'm just exploring all my options and never been around indexable
tools. Gary
(19612) |
| Gary, I use
indexable triangle inserts on my 10K. I bought a 1/2" sq. shank
toolholder from www.plastools.com seems to be working good. The 3/8
I.C. (inscribed circle) triangle inserts seem to be the cheapest some
for a dollar each. www.grizzly.com has some toolholders with a 5/8"
sq. shank that uses their inserts and they are a dollar each
also. Bob
(19613) |
| For home shop
machining I don't understand why anyone would use carbide inserts
when HSS inserts are available so reasonably from
http://www.arwarnerco.com/
I use with my Aloris AXA tool holder on my 9" South Bend. I use the
small 3/8 Warner tool holder using 1/4 I.C. inserts, they're cheaper
than the next size larger, the 1/2 holder. I also grind my own HSS
for special applications for use directly in the Aloris tool holder
or even going back to the lantern tool holder if I have to. I even
regrind the Warner HSS inserts on occasion. I have no way of
sharpening or touching -up Carbide so why mess with it. Neil (19614) |
| You can get a
insert holder from Aloris and I believe from Dorian as well with the
dovetail to fit directly on the AXA tool post. There are also square
shank sets that fit into the standard tool holder and accept the
inserts, Enco is one that carries them, I assume many others do as
well. Most of the brazed tool bits are junk in my opinion. The
inserts are made for production so they work considerably better.
You can touch them up on a diamond lap, if you feel the need to. I
personally prefer cobalt HSS and the largest tool bit than I can. I
don't do any machining on tough ugly material at the present time
that would require carbide. JP
(19622) |
| I only use carbide
when I have to, either on hardened or abrasive material. I prefer
indexable to brazed on. Many HSM's fancy using carbide as the end
all and such, but in most cases it is not necessary. I know a
machinist who used Cobalt square banks (ground to whatever shape
needed) and he turned stainless almost exclusively. HSS cuts better
than Carbide because carbide cannot get the edge HSS can obtain.
This means less stress and strain on low-power machines. Carbide
stays relatively sharp much longer. I personally don't mind keeping
sharpening the HSS bit. If the machine is very worn or sloppy,
carbide is one of the worst things to use as the edge will chip
often. If the machine cannot handle the speed and feed rates of
carbide (3 to 5 times faster than HSS), and the belt slips or the
motor stalls when you try to run carbides at their intended speed
and feed then it shouldn't be used. Old SBs were designed for use
with HSS bits. Bronze bushing or C.I (some old lathes had the
hardened spindle run directly in the machined casting) headstocks
are not designed to run at 1500 to 3000 Rpms which small stock
demands, and carbide needs to run effectively. Depth of cut is much
deeper with carbide as well, and if the machine cannot take deep
roughing cuts, and in some cases a deep final pass, I don't
recommend using it unless necessary. Gabe
(19624) |
| Gary - you've asked
, so I'll give you my angle on the subject.....I run a one man
job/production shop (this is SOUTHBENDLATHE ,and not...... The
HomeShopMachinist-... right?) - you're already using brazed carbides
and wanted to investigate inserts , so here goes! (these are tool
choices that I prefer, I'm merely suggesting...not preaching. I'm
sure 9/10 readers will disagree, differ, etc with my choices, but
that's o.k. too. I recommend eBay for carbide tooling. you can find
first rate stuff( kennametal , sandvik , summitomo , carboloy ,
iscar , valenite , vr-wesson, firth-sterling,........) it's mostly
aerospace and other factory surplus (when a large production run
has ended, the used/unused tooling purchased for that job is often
sold off for cheap). I buy turning tools and inserts for next to
nothing ($5-$20 typically for turning tools) (.10 - 1.00 each type
for inserts) most of the brands mentioned provide application
recommendations and guides for their products (grades, coatings, chipbreakers, etc.) all you have to do is ask. also, most
major tool catalogs- msc, rutland tool , pts , etc ... have
extensive, exhaustive sections on carbide inserts (many 100+ pages!)
, often with cross references- so when you find a deal , you'll know
what you're looking at. As for specifics: I personally prefer
negative raked tools whenever I can use them , most especially in
steel. On my sbl 16" I like TNMG 432 (TRIANGLE NEG , 6 CUTTING
INDEXES) - triangles are a good balance of strength , versatility ,
and economy- with a RH triangular tool , you can face, chamfer, and
turn to a shoulder...+ you get 6 cutting edges from 1 insert. with
ticn coated vr-wesson fansteel 432's, I always get a MIRROR FINISH
on steel down to 1/2" diameter. for my sbl 10" , I like tnmp-322
inserts. They combine a negative approach with a positive chipbreaker.
For most machining, I HATE the tpu/tpg/tct/tt positive
series inserts that seem to get marketed at smaller machines.
they've very delicate edges, are prone to chip, burn easily with
moderate heat, and don't give the glass-smooth finish that is much
easier (for me) to get with neg. inserts + they only have 3 indexes.
Also- tpu/tpg/tct/tt 's aren't often as available at surplus that
I've seen. Lastly, on my Taig lathe (4" swing ) I use tnmg 221
inserts. Positive rake has its place for my delicate setups , thin
parts, very small diameters, etc. many machinists swear by hi-pos
inserts, and that's good too. machining is an art , not a science -
there are as many ways to cut as there are materials to be cut.
No-one's absolutely right or wrong. If your leather belt slips
excessively: check out:
http://home.earthlink.net/~ninenines/index.html c.m.
(19629) |
| H.S. steel
inserts |
| Neil, How is A.R.
Warner to do business with? Did they have any minimum order size?
Will they sell to individuals or only a business? How much do steel
inserts typically cost? I checked they link you provided, but not
many detail are available. JD
(20034) |
| I just contacted
them about buying inserts. They replied back with the answer you
have to order from http://www.littlemachineshop.com they don't have
a min but they are about $5.00 each. Bob (20035) |
| JD, Yes, Warner's
web site is a little skimpy. They are great people to do business
with, it is a family business. I think it is the sons wife that
answers the phone. I suggest you call them. The wife put me right
thru to her husband and I discussed at length what I was doing, I
have a 9" South Bend and an Aloris AXA wedge type tool post and
numerous Aloris and other tool holders. I was considering the 1/2"
toolholder kit which uses the TPMB-322 (3/8 I.C. insert) but he
suggested I purchase the 3/8" toolholder which uses the TPMB-222
(1/4 I.C. insert). I thought "big" would be better but he suggested
with the small work I do, smaller is better, it would get into
tighter quarters and the inserts are cheaper, $4 each vs. $7 each
for the larger. Unfortunately you have to buy in min. quantity of
ten (10) so you're looking at $40 vs. $70. The inserts are available
in 1/32 or 1/64 tip radius and you can mix sizes in your ten
quantity order. He said they have an older 9" South Bend they he
uses occasionally for odd jobs so I figured he new what he was
talking about. I'm glad I bought the smaller 3/8 toolholder. It has
been more than adequate for everything I've done. Most of my turning
is under 2 1/2" and a lot is in aluminum. The inserts last a long
time and can be touched up if you are so inclined. On occasion I use
a comparable carbide insert (I have some that I use in my endmills)
but I like the Warner HSS inserts much better. Other than the min.
quantity on the inserts I don't think they have a min. order size.
For what it is worth I'll mention something about toolholders.
Warner's kit of 4 toolholders, wrench, etc. is much nicer (and more
expensive) than the cheap imports you see all the time. I have both.
Warner's toolholders are 3 1/2" lg. vs. 2 1/2" lg. for the cheap
imports. The 3 1/2" lg. holder is just right for the Aloris AXA
toolholder in that all four of the set screws clamp down on the 3/8
square shank. With the imports only three of the four clamping set
screws can be used. I bought the Warner kit and then later I
purchased the imports. If you're trying to save a buck purchase the
import toolholders and the Warner inserts. They'll work together
fine. I really suggest you call them and get friendly, try and talk
with the son, sorry I don't remember his name. Request all their
literature including their insert identification chart. Feel free to
mention my name, tell them I'm their best salesman. They did a
special order for me a while back, making an odd angled straight
tool bit that I can cut-off to length and grind a cutting edge for
use in an expensive Criterion boring bar that I purchased on eBay
for $10. Criterion sells carbide bits for it but I don't need
carbide and they're expensive. Again, I think they are great people
and yes they will do business with individuals. Let me know how you
make out JD. Neil B. (20037) |
| I have purchased
from Art Warner several times before and can say nothing bad about
them. I still have some T, C and D style inserts I purchased a few
years ago. I am still using them. As your edge wears down you just
hone it to sharpen it back up. They are great BUT you must run them
slow. If you run them too fast they heat up and will not hold an
edge. It is just like working with a HSS bit but is in insert style.
The inserts are not for everyone. They are a very nice option if you
can use them. You can create a larger radius for nice finishing
cuts. If you work on alum, brass, bronze, drill rod, mild steel, etc
they work very well. I still use carbide inserts. I normally use the
Warner inserts for good clean finish on steel or when cutting
aluminum. mc_n_g (20041) |
| How does one
get in touch with Art Warner? leeg2543 (20049) |
|
http://www.arwarnerco.com/
(20053) |
| Arthur R. Warner
Co. 701 Despot St. PO Box 1 Latrobe, Pa 15650 724-539-9229
www.arwarnerco.com
(20068) |
| Best tool for
a smooth finish? |
| I have been experimenting with a P W Model B 12X36 lathe.
I am turning aluminum, both Al rods and disks. My problem is, I
can't get the tiny grooves smoothed out so that I can call it
finished. My assortment of cutting tools is basically "eBay", but
they seem to all be too sharply pointed. What cutting tool do I need
to use for the best, smoothest finish on a piece of 3/4 round
aluminum rod? I have tried all the different speeds, that doesn't
seem to help. What would you call it, so that I could ask the
various supply houses for it? Wade
(21874) |
| A round nose HSS
tool with a polished cutting edge and slow auto feed rate. Southbend
published a book 'How to Run a Lathe' and Sheldon published a
similar one. Both of them contain good info on cutting tools and
basic lathe operations. You can get them from Lindsay books for
under $10 each. JP (21877) |
| Go to the files
section and read the file "stantoolgrinding". Although you
haven't
said so I would guess you have a single point tool bit. You should
look into a tool with a radius. You may be making very fine threads.
Jim B. (21878) |
| Wade, Tom had a
post not long ago: Now for finishing depth of cut. The feed should
be less than the tool nose radius. The depth of cut should be at
least twice the tool nose radius (TNR). The feed so the TNR doesn't
skip over material, i.e. thread. The depth of cut, so the TNR is
stabilized in the cut. If it is only cutting on the radius, then the
tool bounces.
(21883) |
| Grind
and then stone a really round nose on one of the tool bits with
plenty of rake and clearance. Set the tool on center, positioned so
that an edge of the tool nose starts the cut and progressively
finishes the cut as you advance the tool bit along the work.
Lubricate with kerosene or other suitable fluid. If you don't know
to place the tool on center send me an e mail for
instructions. (21884) |
| Thanks for the
details. I place my tool on center using a dead center in the tail
stock, and this seems pretty accurate in this lathe. Because of my
toolholder arrangement, the tool necessarily "angles up" towards the
work piece so eyeballing it can be confusing. I do understand the
importance of centering, because I've seen what happens when the
tool is not centered. Beyond that, I can use a lesson, I guess. I
need to get some 3/8" HSS blanks and try grinding my own tools. I
thought, perhaps, I could buy one already professionally made. I'm
really sorry to drag you all back to the beginning on this, and
really appreciate your time and thoughts. Wade (21887) |
| George, First,
thank you for your help. So what we're talking about here is: for a
tool with a 1/16" radius, the depth of cut should be 1/8"?? This
could be where I have gotten into trouble. I am not taking that much
material at any one time. I was considering a 1/8" radius tool,
which would require a 1/4" depth of cut. Could this be correct? I
tried using the search function to see if the subject had been
previously discussed, but I find the YAHOO search function to be
pretty awful, consequently didn't find anything useful. Wade (21888) |
| Wade, A 1/16 radius
seems HUGE! Perhaps your "radius" is really a "diameter"? Just
looked in a Travers flyer and the typical radii of turning inserts
(no different than toolbits for geometry) is 1/32 or 1/64. At the
larger (1/32) radius the depth of cut would be .0625 or larger (1/32
* 2) which is not too much (takes 1/8 of the shaft at a pass. George
(21901) |
| George, I WAS
thinking in terms of diameter - it is beginning to sink in!
Wade (21903) |
| I'm working with cutting speeds and tool bits and
finishes. My machinist friend told me he roughs at .010 and finishes
at .005. I'm at about 800 RPMs on my heavy 10, using C5 carbide
inserts. I present the cutting tip radius about directly into the
work. The finish cleans up nicely and any final work can be done
with a file and emery. (21926) |
| That sounds
great. I've also had much better luck today using my tools with
carbide inserts than I did with all the other tools I bought off
ebay. I was using 525 RPM, and I haven't tried "straight in" yet,
but my finish today was quite shiny and made me feel good about my
result. What a difference to be able to get something acceptable for
a change. I guess there is no substitute for experience. Wade (21927) |
| The
nose radius of the carbide insert is in that mix as well. I saw a
chart somewhere. carbidedepot maybe? I think I have it on my
drive is you want a copy. It gives microinche finish for a given
nose radius and feed speed. Let me know if you want it.
Randy (21932) |
| Cutter bit
grinding block |
| Has anyone used the
"cutter bit grinding block" as seen in the army tech. manual, pg.
33? Seems like a great item for the novice (me) to aid in grinding
toolbits. Was this made by SB? Anyone have any pics of this jig?
Tim (22426) |
| I have one Tim. It
does work for me. I believe someone skilled, which I am not, would
do OK without it. Mine was supplied by Southbend (don't know who made
it), I got it from Blue Ridge I think. Someday I'll bite the bullet
take an Intro. to Machine Shop course at the local JC learn all the
tyro things like sharpening tools drill bits. Right now I'm doing
welding classes, am too lazy to mix them. Mike
(22427) |
| Tim, I have seen
them advertised on Ebay at one time. There is a Quorn tool grinder
yahoo group. That tool grinder setup is pretty complete but takes
some work to build. There is another one called the tinker that some
have built. Both of these are used for many types of tools so they
are more complex. There is a site by Chris Heapy in the UK that
shows grinding tool bits on a wheel using small wedge blocks.
Someone just posted a link a short time ago for a wheel with
adjustable side tables for tool bit grinding. You can go from simple
to complicated in grinding tools. Do a web search on what I
mentioned above when you have the time. JP (22430) |
| That was at the
mwhints3 group with the Duplex articles from ME on cutter and drill
grinding. JWE (22431) |
| Carbide
tooling - Doing something wrong? |
| I picked up a bunch
of 'cheapie' carbide bits and have been disappointed with their
performance compared to self-ground tooling. The carbide bits, which
are all fairly sharp and pointy, leave tooling marks in the work
similar to a roughing tool regardless of feed or spindle speed (at
least as far as I've found). Yet there's alot of carbide bits
available so there must be alot of folks using them. Is there
something I'm missing that's the key to getting a nice finish with
these bits? Tj
(23732) |
| The cheap tools are
just that. If you are going to use them you will have to re grind
them with a diamond wheel. NOT a green wheel. If you wish you can
put a slight radius on with a fine diamond file. I use carbide most
of the time and have no problems with it. Aluminum, brass , Steel or
stainless steel. (23734) |
| TJ, I don't know much
about carbide bits but will let you know what has helped me the
most. I read up on the different angels and such in the front of
like MSC, Enco and all where they explain the difference in the
rakes and etc. Then you will find a rounder point for a finer cut
and etc and you will want a relief which I found on most is nearly O
and I like 7 to 11 deg. and set it flat and just a hair below center
if anything. Then I try and cut a break of feed for the tool width
. Like if the tool is for ex. 25 thou wide don't feed that long. feed
use like 15 thou. Also you can swing the cutter so the point is not
straight in but at an angel using more of the side of the bit kinda
artificially making the bit tip bulkier. Don't know if this will help
or not but I have used the old hss single points for years and this
is almost as bad as learning computers but once you catch on to a
few things that work for you you will like the life of the tools.
Grumpy (23736) |
| I have never used
any that were any good either, they all seem to chip real easy. The
inserts are another story. They come in many grades and styles to
fit the application. It seems you get what you pay for with carbide
bits. Cobalt HSS sharpens easily and does about everything I need to
do so that is what I use. I have no need to cut exotic material.
JP (23738) |
| William, Are
you sure a green wheel won't touch a carbide turning tool? I bought
one (green wheel) a while back for just that reason but haven't had
the chance to do anything with it yet. It said on the info with the
wheel it would sharpen carbide tooling. I hope I wasn't mislead
-again I do have some diamond files if need be. Tom
(23739) |
| At the
(great) risk of inserting my foot into my mouth, I have been told
that Carbide works best for high rates of feed and speed. My BIL
sells cutting tools, (Mills mostly, but also other stuff.) and
snickers at the HSS bits I use in my SB. However, he readily admits
that the tooling he's used to is run much more aggressively than I
ever can. Regarding green wheels, The grinding shops use green
wheels specifically for carbide. However, a diamond wheel will work
well too, and may leave a better finish. I touch up carbide with a
green hand stone and am happy with the result. Regarding carbide.
The chorus says you get what you pay for. One of the wood working
mags did a side by side test of carbide routah bits a while back.
The results mirrored the price. The Eastern import bits did not cut
as well or last as long as domestic or European stuff. Probably QC
issues. Thansk for reading my prattle if you lasted this long. Mike
(23740) |
| Tom Green wheels
are specifically for carbide tooling, they should never be used for
grinding steel. JWE (23742) |
| I use TPG and
TPU, Triangle, 11 deg relief and the G stands for Ground, the TPU
for un-ground. The TPU is good for rough cuts and I don't even try to
take a cut of less than about 25 thou. The TPG is used for
everything
else. I use high quality hand ground bits for everything less than
steel and carbide for all the really hard stuff. But the key may be
a heavier feed and a deeper cut. If nothing else, you have roughing
cutters. Dave
(23744) |
| Green wheels are designed for carbide sharpening. But....
the diamond will get a finer edge and deliver a better cut. As I
stated in my previous post on inserts, TPU vs. TPG. I have a hard
time telling them apart by a glance, but the TPG has a ground wall
and they both have a ground top. I have often done a first rough cut,
then a finish cut to see the finish from the tool, and then swapped
tools to get the best finish. Seems carbide does great when HSS
tears and vice-versa. then take my second rough cut and so on.
Having both sides of the cutter ground can make a huge difference.
Dave
(23746) |
| That at least used
to be true. I made my living in the cutting tools industry back in
the 70 s and 80 s and for the best finish on lathes like ours were
slower feeds with tool steel. Dave (23748) |
| Another
consideration is the rake of the tool holder. Positive, neutral or
negative. If you bought the cheap 5 or 6 piece Chinese set, then I
think it neutral. Some of the cheap sets are negative. This isn't
good for a low powered machine like the 10K or 9. It pushes away the
work piece and our little lathes are not rigid enough to handle it.
I have the American made set of 5 or 6 tool holders and they seemed
to work OK. There's a lot of specifics when using carbides. The type
of carbide, type of material to be cut, holder etc. Speeds and feeds
can really affect finish and wear factors. From the first post it
sounded like you had what would look like a threaded finish. If so
,and I think JP addressed it or someone else, then slow down the
feed. The feed shouldn't be more than the tool nose radius if not
half. Also, it might help is the depth of cut is 2X the TNR (tool
nose radius). Tom
(23749) |
| Green wheels are OK
for roughing, but you will not get a real nice edge. Bruce (23751) |
| I don't know where most
of you are coming from. I use carbide every day. Grade C6 Wear
resistant. I sharpen them on a diamond wheel. I get the Enco cheap
batch 20 +/- cutters for some where round $30.00 I take any where
from .100 .Same speed same feed rate. Some where around .003/. I can
also take a couple of tenths off. Same tool same feed. I cut
aluminum, brass, bronze, SS steel and 4130 and 4140. Same tool same
feed or greater. RPM is not a big factor. If your machine can handle
it. I have a 1942 9" SB With the original 1/2 hp motor. About the
only thing I use high speed for is Tercite Delrin etc. And with a
sharp point. Bruce (23758) |
| Bruce, which
carbide inserts are you using? TCMT, TPG, TPU, TNMC? This might give
some insight into the question raised by others concerning rake,
positive, neutral, or negative.
(23759) |
| I don't use very
many inserts. I use mostly carbide tipped tool bits. They are less
expensive and can be sharpened till they are just plain GONE. I buy
the 38 piece set when it is on sale for $29.00 #383-4400. I can
sharpen them to just about any configuration I need. In most cases
the rake is neutral and on dead center or just below dead center The
few inserts I do use are for threading , "O" ring grooves and the
like. Bruce (23764) |
| Thank You JW. That
is what I had planned doing with it. Nice to know I did get the right
information after all. Tom (23765) |
| Yes,
I agree with you Bruce. I don't see any problem with carbide
tooling. I have a 1949 Herbert lathe about 7x24. I bought some
indexable carbide tips and tool holder. I expected it to work, in
fact I never even considered the thought that I might have a problem
(???). I just mounted the toolholder with tip and started work. I
get a nice fine finish if required, and can take a nice chunk out of
the material when roughing. BTW The tool holder has negative rake.
Peter (23769) |
| The carbide wants a deep cut so slowing down the
feed is not as wise as using a higher radius. Also, depending on the
cut, you can use just the point, or angle it to take a broader cut
and reduce or eliminate the 'threads'. Dave
(23770) |
| This is why the grinder machines for green wheels have very
substantial tables and little squares for holding the tooling. Hand
grinding is rough grinding. Dave
(23771) |
| I was wondering if
William was talking about something even I have come across in my
short machining career. I was looking at a grinding wheel that to me
looked "green" but a machinist in the shop caught me and said it was
just an aluminum oxide one. To me it really looked green. Now that I
actually have my own green stone it is a vivid green and I wouldn't
confuse mine with an old aluminum wheel. Tom
(23772) |
| I used to have a 10 pound can of inserts. I had planned on one
day, making my own braised on tool bits and hand grinding them.
Maybe if I get that quality grinder I'll do that. But, one thing we
danced around it the difference between the cutter shape of an
insert vs. hand ground. The insert is an equilateral triangle so
each side is 60 degrees. That means a xx2 has a 2/64 radius and on a
heavy feed rate, the cut will appear threaded. The bellied triangle
inserts reduce point, as will the square and also the way you hold
the tool. http://www.carbidedepot.com/holders.asp and a hand ground
turning tool will have even less clearance and leave less of a
ridge. Dave
(23773) |
| The standard grinding wheels are
aluminum oxide and will shatter the carbide. the 'green' wheels we
talk about are silicone-carbide wheels and specifically designed for
grinding carbide tooling. If, however, you bounce the tool onto the
wheel, it will flake. if you do not have a steady hand and alter the
angle, you can get less than a good edge. if you press too hard, you
can overheat the tool. and if you quench an overheated tool, you can
crack the carbide. Now the good news ! It does not take long to get
a feel for grinding with one. And although the above problems exist,
they are rare in occurrence. If you are half decent with grinding
HSS, carbide should be easy. if you can't grind HSS worth a darn,
look into indexable inserts ! Dave
(23774) |
| Dave, Any thoughts
on using the chuck to turn the silicon carbide wheel and using the
tool post to hold the carbide tipped bit while sharpening?
Fred (23782) |
| DON'T DO IT!! First
you don't have the RPMS. Second you are going to cover your lathe
with grit and it works wonders under you saddle. (23783) |
| Absolutely! I use a
1-1/2" x 8" silicon carbide wheel on a dedicated grinder to sharpen
my carbides and it works well but it makes very abrasive dust and a
lot of it. That's why it's located on the other side of the shop
from the machine tools. Also, a nice little diamond dresser is
required to keep the wheel square and using this makes a ton of
dust. I usually grind away the carbon steel shank under the carbide
on a standard wheel first, then sharpen the carbide edge on the
green wheel. BTW, I've never had any trouble using the inexpensive
brazed carbides for roughing and finishing cuts. I don't put much
radius on the tip so they do fracture there sometimes, but they are
so inexpensive and so easy to sharpen right down to almost nothing
left that I don't worry about it. Ed (23808) |
| Ed That pretty much
jives with our experience here in the shop. We make a lot of special
form tools for general machine and the B S screw machines from the
Enco $29 special brazed tools. JWE (23813) |
| To add to this,
Carbide is not good for your lungs. Basically, its carbon or coal,
as in black lung. The one shop I worked in, actually work for the
same company as a drafter, has a vacuum air cleaner on the grinders.
Tom (23816) |
| Radius tools
|
| Can someone explain
the use of radius tools? I just bought a lot on *bay to get a chuck,
and ended up with 1" and 1.25" radius tools. I have no idea how to
use them. Do these form a radius like you would in metal spinning or
what? They do not appear to be cutting tools. They look like tool
holders with a disc mounted to the end. Mike
(25477) |
| Mike, Without
seeing them they are prob used as checking gauges as you cut the
radius. Cut a little then check. Bob (25478) |
| How about this?
http://cgi.ebay.com/ws/eBayISAPI.dllViewItemrd=1item=6155294816ssPageName=STRK:MEWA:ITBR Mike
(25479) |
| Mike, They do look
like a home made lathe cutting tool. Spinning tools are hand held at
least the ones I used were. Bob (25480) |
| Mike, Those are the
HOLDER for a radius tool, not the radius tool itself. JP
(25482) |
| I concur. the two round bits look like they are form tools. They
make round carbide inserts in similar fashion. The idea is that you
cut near the shoulder with your regular turning and facing cutter,
then plunge one of the round bits in and remove the metal and leave
a nice radius. Nice set of tools. I found I could get HUGE holders,
ones that were an inch or more high, rather easily. it was the
smaller ones that are hard to find. My cutoff tool is HUGE for a 9"
lathe. thank goodness for milling machines ! A also found Travers
tool to be the catalogue with these types of tools and similar ones
for the small shop guys. Dave
(25487) |
| JP I
think they are plunge tools. maybe if there are numbers on them you
can let us know. If you look at the one near the center, you can see
some surface grinding, probably re-sharpening. Also, the 'insert'
for lack of a better word, is just a round part that is or is not
tapered. These appear tapered for relief. You sharpen by removing
the top layer. and rotate a little to get a new edge. As form tools,
they are easy to make. and actually a neat home brew project. It's
just that not many people are trying to get a round inside corner
with that size radius. Dave (25488) |
| Tooling
dealers in Richmond VA area? |
| I will be in
Richmond next week. Does anybody know of any used tool dealers that
might be worth a visit. Mark (26138) |
| Put Dempsey and
Company at the top of your list. Great place to hang out especially
on Saturday mornings. Here is a link:
http://www.dempseyandco.com
John (26143) |
