| Parting tool chatter
(Sep 25, 2001) |
Cutter size (May 23,
2003) |
| Proper Cutoff Techniques (Dec 5, 2001) |
How
to cut disk? (Oct 18, 2003) |
| Cutting oil- newbie questions
(Jun 28, 2002) |
Cutting HSS (Jan 20, 2004) |
| Proper cutoff tool usage
(Dec 31, 2002) |
Cutting/coolant solutions? (Feb 27, 2004) |
| Cutting off (Apr 25,
2003) |
Cutting urethane (Jul 31, 2004) |
| Using cut-off tools (Apr
28, 2003) |
Same Speed Same Feed Different
Cutters (Nov 10, 2004) |
| |
| Parting tool chatter |
| I've tried to use
my parting tool a number of times but every time it chatters, digs
in and throws the belt off. This happens even when I feed at an
extremely slow rate. I've sharpened the tool per the instructions in
the "How To Run a Southbend Lathe" and have taken great care to make
sure the alignment is correct. What could be the problem? Gary (1598) |
| Did you set the height
correctly. It should be just a bit above the centerline of the part,
but not too much. Say about a hair or so. The cutting force will
pull the tool down a bit. If the tool bit is too high it won't be
cutting on the edge. If to low it won't be cutting square to the
edge. I don't know what type of tool holder you are using. If its a
lantern type, look to see when you have it set up that the front
angle of the tool has sufficient clearance. Also, keep the length of
the tool as short as possible. You might put a bit of cutting fluid
on it too. Tom (1599) |
| 1) Extend the tool
the bare minimum needed. 2) Make certain that the cutting edge
elevation is exactly on center, or slightly above. 3) *Increase* the
rate of feed. Orrin (1600) |
| I've had similar experiences.
Assuming that you have done everything the other guys have
suggested; 1. Run the lathe in back gear at the lowest speed
possible 2. Make sure that the part is properly supported in the
chuck or collet, and as close to the chuck or collet as possible.
(Flex in the part is as bad as flex in the tool holder!) 3. Support
the outboard end with a center. 4. Use a little cutting oil. 5.
Brass will want a zero or some negative rake angle. (1602) |
| If all else fails,
take 2 alternating, overlapping plunges to part. Take small amounts
off each time. Some use back-mounted, upside-down parting tools.
Reportedly this is more reliable. (1604) |
| Whenever I run into a particular problem I do a Google search
of the rec.crafts.metalworking newsgroup under the name teenut. This
problem comes up cyclicly and Robert often had something to observe
on the subject. Here's one snippet of what Robert had to say, based
on 50 years in the business: Re: Parting tool use and questions?
Sun, 06 Aug 2000 12:33:17 GMT Robert Bastow teenut@N... Newsgroups:
rec.crafts.metalworking Then raweich@m... wrote: Then Robert Bastow
wrote: "Sound advice..to which I would add this: Most people treat
the pre-ground HSS parting blades as a finished tool, ready for use.
It is NOT! No more than a ground, square, HSS tool bit is a ready to
use tool. Parting tools NEED side clearance. This must be ground
into the blade before use. When re-sharpening has reduced the length
of useable blade below the radius of the piece to be parted
off. start again! Snap or grind off the short end and regrind side
clearance on a new section...new blades are cheap enough to buy!
Let's belay all this crap about whether the blade should be at,
above or below center. ANY and EVERY lathe tool should be set at
dead center height. PERIOD. If you get better results by not doing
so. you are doing something WRONG and need to re-examine the
geometry of your tool bit. Unless you are parting off SMALL
diameters, and wish to reduce or eliminate the center "Pip", the
nose of the tool should be ground SQUARE to the body. Any angle to
the nose will, invariably, deflect the blade to one side, during
deep cuts. resulting in binding, rough finish, non-flat surfaces or
breakage. More importantly, an angled cutting edge produces a chip
WIDER than the slot. how do you expect this to escape freely from
the cut? Better, even than a square grind, is a slight radius, or as
I use a broad "Vee" shape to the nose. This flows the chip in on
itself, producing chips that are noticeably narrower than the cut
and which clear the slot easily. If you want to add belt to
suspenders, use a tiny mounted point to grind a shallow, radiused
groove LENGTHWISE in the top face of the tool. Examine a carbide,
inserted parting tool tip, to get an idea of the best geometry to
achieve. Chatter is reduced by INCREASING feed! Power feed will give
best results. Rigidity of the entire set up is next to Godliness!
Lock all slides not in use. Normal cutting speeds are the
rule. Reduce ONLY if your rigidity is suspect. Reduce overhang to a
minimum. both in the tool setup and the workpiece. Avoid Lantern
type tool posts and Armstrong tool holders like the plague.
Especially the angled parting tool holders. the worst abomination
ever foisted on unsuspecting machinists. If you can't afford a rigid
tool post. MAKE one! Rear mounted toolposts have definite
advantages. Deflection of the tool or workpiece tends to lift the
cutting edge OUT of the cut, rather than forcing it deeper...this by
dint of the geometry involved. Mounting the parting tool upside
down, in the front tool post, and running in reverse, has the same
effect. This same arrangement works wonders with broad form tools
too. Part off as close to the chuck as possible. If a long overhang
is unavoidable, or the parted off piece is relatively long. use
GENTLE pressure from the tailstock to prevent whipping and chatter.
Remove this just before final breakthrough or you may get a jam up.
Judicious use of a fixed steady, a wedge of wood 'twixt toolpost and
job, or, (dare I say it,) a well lubed hand, (NO GLOVES PLEASE!!)
will also help to reduce chatter in these circumstances. Lubrication
is a MUST except on free cutting brass and MAYBE good grades of grey
iron. Drip feed or flood lubrication, matters not. Just bear in mind
that a happy parting tool sounds like frying bacon. The instant it
starts sounding grouchy add more lube. teenut
(1612) |
| For many years
parting off was the most difficult operation I had too do. Then I
found a fantastic solution to this problem. Its called a goose neck
spring parting tool holder. Mine for my 9" SB is a straight shank
Armstrong No S-20. I used to creep up and back off to get a cut and
Quite frequently resort to a hacksaw to cut the last 1/4". Now I
powerfeed quickly all the way. Assuming you have a rigid setup the
only other thing needed is a good cutting oil. I use an old tooth
brush dipped in Rigid dark threading oil and held on the cut. The
MSC new 2002 cat has Armstrong gooseneck parting tool holder for the
9" for $146. Unfortunately the 13" lathe size is $ 239, and 16" is
$298. Because they work so well I have acquired several other spring
tool holders mostly for 1/4 and 3/8" bits. Great for thread cutting.
These even work well in shapers. A couple of others ones I have are
home made. If you look at the cat pic you could machine one
yourself. There may even be designs on the rec.crafts.metalworking
newsgroup. Walt (1616) |
| Lots of great
advice on parting. One other tip on parting that I got from Scott
Logan: * If possible, part with power in-feed This will give you a
smooth, fairly fast feed rate, rather than a jerky, hand feed rate.
It really works better. You may wet your pants the first time you
try it, but it really does work. Bob (1619) |
| Proper Cutoff
Techniques |
| Are there
any rules of thumb or recommendations from the "old hands" for
properly cutting off finished pieces? Is the technique different for
pieces between centers as opposed to being in chuck or collet only?
Should the diameter be reduced to zero with the part actually
falling off or is the diameter reduced to a "safe" point and then
hack-sawed off? Should there be some side-to-side "wiggle room" cuts
or just a direct inward cut the width of the cutter? Just curious as
to how folks "in-the-know" deal with cutting off situations. Jim
(2323) |
| A few months
back this was discussed. I will say my technique would vary as to
part and weather it is a manual machine or CNC. Also, type of
material and size of part comes into play. Ideally, I want to make
one straight in cut using power feed. Peck feeding with a cutoff
tool can create problems. With a CNC machine and possibly a manual
machine, the size of the part can effect if I want to completely cut
off the part or just have to snap it off. This works well if there
is a hole through the part. Smaller parts (they tend to fly off some
where) or parts that may get dinged are good candidates to just have
the part held on to be snapped off. They may not land in the parts
catcher in a CNC lathe. Basic recommendations: Look up Ron's post and
follow it. Failing that : 1.The tool height should be on center or
slightly above center of Diameter of part. This depends on the
flexing of the machine and tool. You want the tool while cutting on
center. The cutting will draw the tool down a bit when cutting. (see
#2) 2.Keep tool length (tool blade , tool holder, etc) as short as
possible to reduce flexing (a major problem) 3.Try to keep an even
feed, try a slow feed with power feed. 4.Lub the cut with oil during
the process. 5.Adjust speeds and feeds as needed and for the type of
material. Tom (2324) |
| Here are a couple
of pointers. First do NOT part off between centers. The work will
bind and something in the chain will get damaged. You can part down
until almost through, then finish with a hacksaw off the lathe. Use
a stone and hone the cutting point of the parting blade. Get it
sharp. Use lots of oil or lube of choice based on material. Align
the cutoff blade carefully. If the sides start to rub, the blade and
work heats up, and you start to bind. Use a good cutoff tool and
blade. The $20 made in India tool I bought years ago never worked
well for me. A good parting tool and blade cleared up most of the
parting problems I had. Be sure the tip of the blade is square to
the blade. If it is a skew point, it will try to cut a curve. Feed
aggressively. Slow feeding makes heat. If the chips don't clear,
retract and clear them off with a brush, then resume. Parting
requires a rigid setup. Part as close to the jaws or steady rest as
possible. A piece may be 2 inches diameter and only 8 inches long,
but if you're parting 6 inches from the chuck you're going to see
things start to wiggle. Use the least extension of the toolholder
and blade as possible. Pay attention to where the compound is when
parting. If the compound is extended, you have a lever. Try to have
the compound set so that the thrust goes straight down to the cross
slide, rather than having the far end of the compound slide waving
in the breeze. Have your gibs set correctly. Loose gibs will cause
you a world of frustration. I often snug the compound gib a bit
before parting. Be sure to be on center or slightly above center. If
you are below center the work will ride up on the blade and catch.
If you are going to have a hole through the center anyway,
drill/bore/ream/whatever the hole before parting. The less you have
to bury the blade in the work the easier you life gets. As the
diameter decreases, the more the work wants to catch or chatter.
Stan (2327) |
| What's a "gib?"
Bilal (2342) |
| Bilal, the gibs are
the thin steel strips that are used to adjust the play in the
sliding dovetails of the cross slide and compound. The exposed screw
heads on the sides of these parts are gently snugged up to remove
all looseness in movement. The screws bear on the gib strip, which
in turn slides on the male dovetail. If these are too tight, motion
is difficult. If too loose, the assembly can shake around a bit,
resulting in chatter or varying depth and quality of cut. Stan (2343) |
| Cutting oil-
newbie questions |
| Just wondering what
you guys use for turning (heavy 10, HSS cutters, lantern toolpost)
1- gray iron 2- 2011 aluminum 3- mild steel 4- 4130 Chrome moly
steel anything different for threading the above? Tom
(4794) |
| I have been using a
product called cool tool 2.The stuff is non toxic, as these things
go, and the smoke from it doesn't bother my sinuses. Its supposed to be
good for all metals. All the regular supply houses handle it. RC
(4795) |
| Tom; Here goes:
Cast Iron - cut dry 2011 Al - kerosene, tapmagic, cool tool, WD40.
Kero is pretty darn cheap, works well, and isn't any more flammable
than a lot of other lubes. I just mention this because sometimes
people get nervous about using the same stuff that can be used in a
heater :-) Mild Steel, Chrome moly - any cutting oil, I often use
Mitee dark thread cutting lube thinned with a bit of kero. It's
cheap and works pretty well. Quite often I just cut mild steel dry,
at least for the majority of stock removal, occasionally giving a
bit of lube if chips seems to be welding to the tip. And a few more:
Brass - Dry Copper - milk/half and half/whipping cream I use 1/2
inch indexable tooling a lot. Cheap per tip and good for heavy fast
cutting. Critical stuff often gets a finish pass with M2 or better
ground to the correct tip geometry for the material and task at
hand. Stan (4796) |
| Tom, I use
Tri-COOL. It cost about $10 a quart. It is biodegradable and water
soluble. I mix it in a spray bottle. I am using on an EMCO CNC
machine. I think it does ok. I was wondering on your opinion on the
2011 Aluminum. Its suppose to be a free cutting type. Do you notice
a difference between it and 6061? Enough to justify its cost? I am
using an indexable inserts. Right now I am using a Rouse-Arno
Aluminum type. Others have something similar. Tom (4798) |
| Proper cutoff
tool usage |
| Last night I
made up a mount for my unknown manufacturer milling attachment.
Everything went as I expected except for the parting part of the
process. What're the tricks to using a parting tool? I've got a 3/32
x 1/2 cobalt cut off blade. The angle was probably ground a little
too sharp, but not ridiculously so. I tried it both with the lowest
regular speed and the highest backgear'd speed, with similar
results. Blade was on the centerline of the work. The problem was
that the tool cut _very_ slowly and dug in and slipped the belt
frequently (Belt tension was fine for regular turning). Didn't cut
very smoothly either, and had a tendency to not cut straight in, but
rather to dish the cut a bit. Altogether, it probably took me 15
minutes to a half hour to part off a 1.375" piece of steel. In
'how to run a lathe' they talk about flooding the area with oil,
which I wasn't doing (yes, I frequently read directions after
screwing something up... :-). Does that make a huge difference? I
was also thinking that perhaps I didn't have the cut-off blade
exactly perpendicular to the ways and that was causing the slightly
dished cut and increasing friction, making stalling more likely?
Also... Is there any reason not to use 1/16 x 1/2 blades? Seems like
the less metal I was removing, the better it'd work. Mark (8385) |
| Mark, You
**MUST** use plenty of cutting oil. Only cast iron, 360
alloy brass or some bronzes can be cut dry. A saturated acid brush
is my applicator. Never let the cutting edge get dry. Hot rolled
steel is the worst to part off followed by cold rolled. The tool tip
has to be sharpened square across. Anything else will drive it to
the side. The tip AND sides must be sharp for the full depth of cut,
Anything less will invite dig ins and galling up at the sides. Top
rake can be used for steel, but is not absolutely necessary. I don't
use it. The chip should form as a tight roll, break and begin
another, all the time making a sound sort of like bacon frying.
Lowest back gear RPM is best. Any tendency to chatter means lower
speed or faster feed. Don't baby it, but do force it to cut,
watching for trouble. Did I say use plenty of oil? RichD (8388) |
| I'm not sure what this means.
What's top rake? I'll definitely use oil next time. Lowest back gear
RPM is _really_ slow, like 60 rpm or so (just guessing. Its on a 9"
C). I really want to spin it that slowly? Mark (8390) |
| Cutting off gives
me a fit also. I'm self taught and feel comfortable with all other
procedures I use except cutting off. I get best results with slowest
speed, but had mixed results with oil, ending up not using because
of mess to clean up with not enough results. Almost ground a blade
up trying different angles, rakes, etc. I'm a gingery fan so I use a
lot of cast al and even that soft stuff gives me probs. Was glad to
see the post on this problem as I hadn't thought to ask. I am looking
forward to (hopefully) some answers. bill
(8391) |
| Mark, YES, that
slow. That is why they put back gear on a lathe :-) Top rake is the
groove that is ground into the top at the front edge of a parting
tool. Also, this contributes to chip breaking. Top rake is commonly
used for all steel turning tools. If you use a lantern tool post and
standard tool holders, the top rake is already set. RichD (8392) |
| Mark Although not
as easy to try as Rich's good comments, another key element is tool
mounting rigidity. When I had the original lantern toolpost with the
traditional Armstrong cutoff tool holder, I used to dread cutting
off in almost any material. I could sort of get by with the
techniques suggested by Rich, but it still would sometimes be an
adventure. I then got a QC tool holder (mine happens to be a FIMS,
but Aloris or it's Chinese copies would do just as well). While the
convenience of always having a tool at the proper cutting height,
etc is nice, by far the most significant improvement from the QC
holder in actually machining is in cutting off. I don't even think
about it any more, I just grab the cutoff tool holder, put it in,
and cut away (with lubricant on steel). I use the same cutting speed
rules in FPM I would for ordinary turning of the material at hand. I
still make sure the tool is sharp and straight across, but there is
no "what's going to happen this time?" feeling when I cut off now.
BTW, I have two cutoff tool holders, one with zero top rake for
brass, etc, and the other with top rake (about 10 Deg. if I
recollect) for steel. Mark, you asked what top rake is. It is the
angle relative to horizontal formed by the top of the cutting tool
in the direction perpendicular to the workpiece axis of rotation. So
a tool with positive top rake tends to want to "dig in" to the
workpiece, a good thing for steels (but bad for brass). Frank (8394) |
| Thanks for the definition! I do in fact
have some top rake then, though I'm not sure how much. I forgot to
mention when describing my setup that I have a Phase II quick
change. I'm afraid that years ago I got spoiled when I was doing a
little lathe work at my then employer's machine shop (I'm a computer
geek in real life, but I was racing motorcycles at the time and
couldn't afford to buy parts I could make). I used my recently
acquired 9" once with the regular toolpost and quickly decided that
$100 for a QC was cheap! Speaking of which. Anyone got any
favorite sources for cheap phase II / Aloris AX size tool holders? I
could use another couple regular turning holders. Mark
(8395) |
| Enco sells them for
about $25, I bought several the last time they had a free shipping
special. When they arrived, they were Phase II, rather than generic.
Phase II is just an American importer of Chinese stuff, that stamps
their name on things, but I still like it better than no-name.
C (8396) |
| Like Frank says,
it's always an adventure when parting off, but you learn by mistake
what works by doing it. Regarding lantern toolposts/holders, et al.:
I only keep a set with a lathe for when the time comes to sell it.
Otherwise I'd toss'em into the pasture! A good solid wedge or piston
QC toolpost is the only way to fly. Rich (8398) |
| Cleeve Gives
some fine points about the care and feeding of parting tools. Now
while I have never used or ground a blade the way he shows, I use
T15 "T" style cut-off blades straight in with no rake in the rear ot
in the QC holder at the built in rake thus only needing to sharpen
the front of the blade. For the rest of the article the methods
shown and problems to be avoided are as valid today as when they
were written
http://groups.yahoo.com/group/mwhints/files/Hints%20%26%20Tips/
The file name is 2858-Parting.pdf JWE (8401) |
| Quite a
while ago I posted about how parting off was a nightmare. I'd been
using a 1/8" carbide parting tool, the highest backgear speed, and
no cutting oil on my 9"C. Well, on the advice of everyone here I
parted something else off the other day at the slowest backgear
speed, using a 1/16" HSS parting blade and plenty of cutting fluid.
What a difference! It was super fast or anything, but no more
stalling and much less swearing. Night and day better. Mark
(9392) |
| Cutting off |
| Bill I'm not sure
what you have in mind here, but if the idea is to cut off (from the
front) by inverting the tool and running the lathe in reverse, be
very careful. With any lathe using a threaded spindle (and I think
all SB9s had threaded spindles), this arrangement makes the cutting
force loosen the chuck on the spindle rather than tightening it.
Even if you get away with it once or a few times it will bite you
eventually. You only have to unscrew the chuck once while machining
something in reverse to drive the message home very clearly. I
expect you would be OK with the work held in a collet (assuming the
collet holder is not one of the threaded variations). Frank
(10458) |
| I fully
understand what you are saying. I would probably be better off
cutting the roundels with a hacksaw or my homemade chop saw. I would
rather be safe than sorry rather than risk injury or worse. Thanks a
lot for the safety tip. Bill C. (10465) |
| Bill Although
cutting off has some inherent geometry advantages using an inverted
tool at the rear (and the normal direction of rotation), cutting off
can be done reasonably well from the front in a small lathe with a
"regular" tool placement and rotation. You need a reasonably rigid
tool holder (i.e. not a lantern holder), a properly sharpened cutoff
tool, proper cutting oil, etc, but it can be made to work. I
wouldn't give up quite yet. Frank (10479) |
| Frank. I think for
now I am just going to keep cutting the pieces with a hacksaw. After
I sell a couple of cannons I may order the T slotted S-4328 cross
slide casting from Metal Lathe. Would be a nice addition for my lathe
anyway. But like I said I will have to try and sell some cannons
first to get the money for it. I don't want to take any chances and
maybe break something on the lathe, I'm still paying on it.
Bill C.
(10480) |
| Frank can you
describe a little about a properly sharpened cut off bit?
Clint (10481) |
| Clint Let me start
by saying I'm not a machinist, and most of what I know comes from
trial and error, reading, etc. I would be happy if someone who does
this for a living and/or had some formal training chimed in as well.
Having said that, here is what I find works. 1. dead sharp- I use a
hard Arkansas stone for final honing, but other methods may work
equally well. Re-sharpen or hone frequently. I find that a not quite
sharp cutting tool just make the finish less than perfect in plain
turning, but has a lot bigger impact in cutting off (things jam,
break, etc). 2. Cutting edge straight across (i.e. exactly parallel
to the turning axis) viewed from the top. Otherwise the tool walks
to the side in cutting off stock of any significant diameter. 3.
About 3 degrees side clearance. This is the angle of the side of the
tool to vertical (on each of the 2 sides) viewed from the end,
giving clearance under the horizontal side edges. Commercial cutting
tool bits come with this angle built in. The trick is to mount the
cutting tool bit in the holder so each side still has this side
relief (i.e. don't let the tool tilt side to the side due to the
mounting). 4. I also grind in about 2 degrees of side relief on each
side. This is the angle between the side of the tool and the work,
viewed from the top. So the top of the bit is wider at the point it
contacts the work than further back. Grinding this involves a
compound angle, since you want to continue having 3 degrees of
clearance (in the vertical dimension) while you grind in 2 degrees
of relief angle viewed from the top. Clearly this relief needs to
continue far enough back on the bit to clear the largest workpiece
radius you plan to cut off. When you align the tool, make sure the
cutting bit is exactly perpendicular to the turning axis (viewed
from the top), so you actually get this clearance on both sides when
cutting. 5 Front Clearance- This is the angle between the front edge
of the tool (viewed from the side) and vertical. For steel you want
this to be small, to give maximum support under the cutting
interface. About 5 degrees is right. For softer materials this can
be larger, perhaps 10 degrees. 6. Top rake- This is the angle
between the top edge of the tool at the cutting point relative to
horizontal, again viewed from the side. for most everything but
brass you want perhaps 5 degrees here. For brass you want zero, or
perhaps even a little bit negative. This says you really need at
least 2 sharpened cutoff tools, one for brass and one for everything
else (much like drill bits, etc). Note all of these angles are for
the tool in its mount. If the tool bit holder holds the tool bit at
some angle to the horizontal (as some lantern type tool holders do)
you need to figure out separately what angles on the tool bit itself
give you these angles when mounted. The angles which typically
change with the mounting method are Front Clearance and Top Rake
(the last two). Frank (10491) |
| Frank, This is one
of the best (most understandable) write-ups that I have seen on this
subject. THANK YOU from another that has always had parting
problems. (10492) |
| I use a much higher
rake, almost 45 degrees on a lot of parts, and have a holder that is
about 30 degrees. I'd post in the photo's section, but it is
currently full. If you want a pic, let me know. Dave (10493) |
| Dave, there is
another site where photos can be posted,
http://groups.yahoo.com/group/SouthBendLathePix/
Bill C. (10494) |
| Frank That is a
real good explanation, ever thought about being a Teacher?
Clint (10495) |
| Dave If you do not
mind, I would like to see the pic, email me.
Clint (10496) |
| Clint Not as a
profession- I have been an engineer since I was about 2 (or so my
parents tell me), and I still think of my job in the context of:
"and they pay us too?". However I do find that, especially in the
last 10 years ago or so, I enjoy teaching. Perhaps if Tyco dumps me,
teaching might make an interesting change, especially if engineering
jobs in NJ are still really scarce for engineers approaching 60.
Frank (10497) |
| Frank is right on
almost all factors in all circumstances when using the normal run of
the mill cut-off blades. Now here is a little secret, they are not
cheap but find some T-style blades made from wrought T-15 material,
with these blades because of both the shape of the blade and the
material it is made from you can get away with a 30 deg rake for
your main relief and for the 1/16 inch or so just under the cutting
edge 15 deg and the blade itself can sit flat in a normal tool
holder. If using a 20 deg Aloris clone holder just do the relief at
a straight 35 deg and cut. After I bough and used my first one of
these blades back in 77 I have used nothing else and every time I
try a standard one I remember why I switched, just like every time I
drive a Ford I remember why I do not own one. JWE (10498) |
| Frank So far I have
not had any trouble using a cut off tool, but I am always hearing
people having trouble? Maybe I have just been lucky or beginners
luck. I take that back, once I had a problem when I was playing
around with sharpening, I had the tip narrower than the rest of the
blade, then I had trouble with it binding as it advance. Only took
one time not to do that any more! It seems to me that the less I try
doing to the tool the better it does, it seems when I try to get
fancy with it is when I get into trouble. Clint (10499) |
| Jim good advice
taken, I sure have to take it now, since you are wise on the ford!
Every once in a while, I have to get a Ford just to remind me why I
drive Chevy about every 15 years or so. Clint (10500) |
| Clint. You're
doing better than me. Tried the cut-off tool again today and had the
same results. The work piece tried to climb the tool again. I reset
the tool to center and tried it again, same thing happened. Reground
the tip and gave it another try, fed the tool into the work piece as
slow as possible and it jammed. I just don't have the knack for it or
I'm doing something wrong. This is getting frustrating. Bill C.
(10501) |
| Bill, are you
using a tailstock center? I had the climbing problem even with a
relatively short piece; tailstock center solved it. Amazed at how
little length it took to mess things up without the center. Ran the
center looser than normal so it didn't try to catch when it got real
near cut through. (10502) |
| Bill How far away
from the chuck are you trying to use the cut off tool? Rigid is the
key word in part off work. There must be no deflection in the piece
part, or chucking method. In hobby lathes this usually means that
the part off tool must be used very close to the chuck or holding
collet. This is especially true if the part being cut off is flimsy.
Rich (10503) |
| 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 honestly don't believe that 9's and light 10's are very rigid
machines. That's why knurling and cut off operations are so touchy.
Lantern toolpost itself is not very rigid. that's why the toll post
block performs better. Not necessary but it really makes you life much
easier. Look in the files section or on metalwebnews for home project
toolposts. Other things that come to mind- no matter how sharp your
tool is it has to EXACTLY ABSOLUTELY perpendicular. Use a known
parallel to set the tool against the face of the chuck. I use a 1-2-3
block against the chuck and another hss bit blank to bear against the
blade. I also try and use the compound to try and bind it all together.
That might be more difficult with lantern style toolpost but certainly
possible. Keep your blade and tool holder stick out as short as
possible. Deflection at the tip is a function of the distance cubed.
Also, what is the diam of the material you are turning? at most, try to
keep a 3:1 ratio of unsupported length to diam. beyond that, use a
steady or tailstock to help out. Tool must be on center and the angle
of blade dead flat. At least the way I grind and use: I use side
tapered cut off bits and only grind the front to 5-7 degrees and then
hone with a stone. lube: set up a drip oiler if you can, or a mister.
Its hard to apply lube and advance the cutter. Consistent even feed is
critical. I can not describe it, I go by feel and watch the chips curl.
Once you master it, it will stay with you. dennis (10507) |
| Dennis. I plan on
making another type tool holder as soon as I can afford to get the
right kind of material to make it from. In the meantime I will try
some of the other methods suggested and see what kind of results
occur. I appreciate everyone's input and all the suggestions put
forth. I really love this little lathe and love using it. It's
probably one of the nicest things I have ever owned and I wouldn't
want anything to break on it due to my ignorance. Bill C.
(10508) |
| Bill It kind of
sounds like something is flexing or giving a little, are you close
to the chuck? any play in the tool holder? Cutter maybe slanted
downward? Just sounds like some giving/flexing of some sort?
Clint (10509) |
| Since you now
have a furnace, you can cast the material needed for a cam/piston
type QC toolpost, out of aluminum. Clint(10510) |
| Dave, I would like
a picture. (10512) |
| I use a QC
tool post and the standard cutoff holder that came with it. I part
stainless, cold and hot rolled steel along with lots and lots of
aluminum. over in the group,
http://groups.yahoo.com/group/SouthBendLathePix/
I created a folder called 'cut-off tools" with 2 pictures. picture
one is a blade that has a high rake, and the relief helps in cutting
off as the chips in aluminum roll tighter and as many know chip
control is often 90% of the problem with a good work. the second is
a cutoff tool holder I purchased from a used too place and uses a
huge blade for my 9" - 1/8" wide compared to the skinny blades of
the AXA QC holder. my carbide tipped cutoff blade if straight, no
relief other than the angle from the holder itself. I also have
another blade that I leave straight, but have both ends ground. One
end cuts of with angle towards the chuck when I'm cutting off scrap,
and the other end with the point towards the tailstock for when I'm
cutting of parts and leaving stock. I have a blade that is flat, do
not use that exclusively. I use the one that matched the work. I keep
an Arkansas stone (very hard) an grind the bits for a shaper edge,
then stone the bits. top, front, both side, then hit the corners.
When I hit the corners, I stone the front laying the stone on the
lower relief and then the cutting edge and hone the cutting edge,
then keeping the stone in that angle, rotate it 45 deg and take any
grinding burrs off the corner, then rotate it again to the side so I
am stoning the side flat. it gives the corner a little radius and
takes off the burrs. use your 10x magnifier to inspect the edge of
the cutter to make sure it is sharp. in the case of my high relief,
I have a flat on the top of the cutting edge, not a knife point. It
is stoned in, and probably only about 10 thou. If you don't have a
drip oiler, consider a small can hanging higher than the part, with
a tube. A clamp on the tube to crimp it to regulate flow and a
magnetic clamp with arm to hold it in position. If you scour old junk
yards, old old old refrigerators used 1/8 dia copper tubing. you can
cut this off with wire cutters and use that as a very skinny straw
for oiling. Pen parts also offer neat tubes and your friends will
flip if they see you using a Gold Cross pen for your lube!
Dave (10519) |
| Hi quality tool
material does go a long way. If you saw my pic, I use a Tantung
blade. at $50.00 it is NOT cheap, but for one blade for years, and
no problems and the bragging rights. Dave (10524) |
| Dave if you
ever see any Vasco Supream 3/32 or 1/8 x 1/2 T-style bits lying
around anywhere grab some for me will you. JWE (10528) |
| I'm
not going into the cutter shape and angles that's been covered pretty
good. And its been said to make sure your centered this is critical.
There was one post I saw on speed's I'd like to restate that most new
chip makers run it to slow for parting of ( my opinion ) and feed to
slow. I am working on a crankshaft for a little engin e. It's disk is
3/8" the shaft is 1/16" one piece. Now I did do this on my little 7x a
lot less ridged that my SB9, cut off tool in front, side front relief,
no bake rake, speed about 500 rpms to start, feed rate I don't know how
to state it for sure but it took less than a min. to cut it off on the
3/8" ,but no a constant rate faster on the start slowing towards the
center, and increasing spindle speed some as you approach center,
cutting fluid was ATF. Just a side thought on cutting off I've been a
wood turner for a long time and I think a good way to get an
understanding of speeds and forces on using a parting off tool might be
to get a cheap parting tool for wood form some one, chuck up some 1"
wood dowel in the lathe and make a bunch of checkers. The Wood Dragon
(10529) |
| Using cut-off
tools |
| As a professional
tool maker, one thing is the rocker type tool posts aren't very
rigid, I just bought my 9" South bend about a week ago and have not
cut on it yet and haven't run one of these little lathes in more
than 20 years, but one thing that I see a lot of inexperienced
operators do is to run the part to slow when they cut it off, I just
cut a 2 1/2" diameter part off with an Aloris tool post at work
yesterday and a 1/8" parting tool, I cut this part off at 355 rpm,
most of the guys I see do this, do it at about 100 rpm which is way
to slow, the material I cut off was also a piece of S-7 tool steel.
The more rigid you can make your set-up the better, I also don't use
oil to lubricate my tools, I use water soluble oil which is a
mixture of about 50 parts water to 1 part oil. No decent tool maker
uses oil any more haven't for 20-30 years, water soluble is much
cheaper, no where near as messy and works generally better on
cutting tools with the exception of taps and reamers. If you have a
pan under your Lathe just use a fish tank pump to supply coolant to
the tip of the tool, just remember to clean the lathe when done
using for the day. (10511) |
| There are a lot of
us home shop guys who have their machines on wooden benches and more
than a few that have there shop carpeted. I am currently working on
adding flood cooling to my band saw and then to my lathe, then the
drill/mill. But, as the time honored tradition, spot lube is the
way most of us go. I know a lot of guys (lots more than I would have
thought) that use lard. The only thing I pay real attention to is
tapping and using tapping fluid. for lathe work, I use what oil is
handy, and if it smokes, the bit is too dull and/or the part
spinning too fast. water-soluble oils are designed to not only add
lubrication, but also cool the part. cold parts and cold tool make
finishes better, edges last longer and parts more repeatable and
metals are not work hardened. way too many benefits not to use them
in any production shop. and since lathe work is confined to a
relatively constant work envelope, it is very easy to add coolant.
compare that to milling machines that need the same benefits, but
have a much larger work envelope. I don' know any shops that use
flood cooling on a knee mill, granted I am not familiar will more
than a half dozen shops, but it seems that only fully enclosed
milling centers have flood cooling. The benefits of flood cooling
are extensive, and if one wanted to add that, the drain pan and
chuck guard are about the only things needed. but water-soluble oils
do rot and stink unless they are changed, and in home environments
where tools are left unused for weeks or months, that means waste.
also water on metal surfaces is bad. the oils will prevent rusting
when the coolant is flowing as the oils attach to the metal, but
after many hours of non use. and that means a thorough wipe down,
followed by a drying, followed by an oiling after each project.
assuming that after your project, you are not using the machine for
a few days. (weeks...) I can't comment on the length of time water
has been used, but I started in a production shop in the mid 70's,
and it was on every production lathe, but not on every lathe. we had
the pumps, the coolant, the drain pans, but just didn't need it on
every lathe. so, I would argue that 'any decent toolmaker' would
more correctly fit any 'professional shop' with the addition of
'when needed' as there are lots of retired guys making very high
quality parts who chose not to use flood cooling for one reason or
another and many shops who chose not to use it for one reason or
another. Dave (10518) |
| Dave, not all water
soluble rot and start smelling or need replacing and there are
additives you can put into them to keep the smell down like cinnamon
oil. When I speak of cooling with water soluble I don't mean
flooding it like a machining center does, put you a gallon milk jug
or coffee can above the machine and use an 1/8" hose with a small
magnetic base to hold a brass tube and let it trickle on the tool,
be it an end mill or a cut off tool or whatever, you can use this
trick on a mill or a lathe. When I made my drip pan for my lathe to
sit on I had a small lip bent on the tray and put a PVC fitting on
the bottom with a plug in it so I can drain the tray into the jug
and keep reusing the water soluble or store it in the jug till I use
it later. Oil is ok for spot use but I never liked using it because
it is messy and takes one hand to use it and I would never run it in
a drip can on a tool because of the mess and sulfur oil stains the
metal on the machine a dark color. Also a large chunk of knee mills
made since the mid 70's have a coolant pump built into the base of
the machine with a flood nozzle and drains in the table plummed to
drain back into the base. (10525) |
| Dave Allow me to
add that water soluble should only be used in light duty situations
where the machine is running at minimum load. We have tried soluble
on every machine in the shop and have gone back to oil on everything
but some of the centerless grinders where the stock removal is not
to heavy and finish quality is nit that important. Everywhere else
in the shop tool life is from 10 to 30 times longer with high
sulfur cutting oils and we are able to run faster cycle times as
well. Good old fashioned brown high sulfur oil is the best tooling
coolant there is when you are doing heavy metal removal. JWE (10526) |
| I agree 100% that
any lube is better than not lube and that cooling is better than
lube alone the messiness of water based solutions is a problem with
come guys with wood benches and not drip pans. I found that mixing
the coolant with water for a cut-off saw yields a nice white milky
fluid, but once thru the pump and it seems to let the oils separate
and then they float to the top. it is well worth the effort, but not
everybody will gain a large benefit. Dave (10532) |
| Cutter size |
| Is there any
advantage to using a 1/2 cutter rather than a 1/4 cutter on a South
Bend 9" Lathe? Both seem to do the job but the 1/2" take forever to
grind on my (not large) grinder. Larry (11413) |
| 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've been using 1/4 on my 12 Atlas because that's what came
with it. Now that I have to buy some more for the SB I thought I'd
check before I'd stock up. Maybe I'll try 3/8 if it doesn't make a
lot of difference. The 1/2 really do take a while to grind. Larry
(11425) |
| 5 to 10% cobalt
Thanks for the tip. I never tried carbide because I have no way to
sharpen them. I tend to take many light cuts anyway. In the past I
was somewhat over protective of the cast gears in my Atlas. The
Atlas always served we well but I saw the SB and fell in love and no
more change gears. Now if I can just learn how to use it.
Larry (11453) |
| I buy 5/16" new and
keep my eye out for used 1/2" already ground in useful shapes. I'll
second the cobalt. Ed (11456) |
| I have no problem
grinding my own tool bits and I prefer 1/4" HSS for my 9" South
Bend. I do not have equipment to grind carbide and I really do not
need carbide as most of my work is small and mild steel or aluminum.
My experience with carbide was production work, heavy cuts and lots
of horsepower, not what I do at home with my South Bend. When I
switched from rocker type tooling to an Aloris tool post and
holders, which work much better with insert type tooling, I
purchased the Arthur R. Warner Co. 1/4" tool holder's which use
their T-15 HSS Throwaway inserts. The insert's look just like
carbide but they are HSS. They are 1/4" I.C. (same as carbide)
triangle shape i.e. three cutting surfaces, 1/32" or 1/64" radius,
and reasonably priced. at $4.00 ea., purchased in quantities of ten,
They can be touched up on your grinder if you are so inclined. They
are available in 3/8" also but the inserts are $7.00 ea. I believe.
I love my system now, very speedy when producing small parts,
especially multiples that necessitate a lot of tool changing. Warner
advertises in Home Shop Machinist, phone
724-539-9229. I highly recommend. If I need special shapes, etc. I
grind my own and sometimes revert to my old rocker holders which I
kept of course. Neil (11476) |
| How to cut
disk? |
| Is it possible to
use my 9" SB to cut 1/16 and 1/8 aluminum plate into 4-6 inch disk?
If so how do suggest I hold to stock. Need 6. Also, how would I go
about knurling the edge? Larry (14481) |
| You can glue them
to a faceplate one at a time on top of a slightly smaller disc or
you can use a center in the tailstock with a cone shaped mandrel a
little smaller than the disc and put enough pressure against the
piece to be cut to hold it. The glue and mandrel together will work
best of all. The backing disc can be held to the faceplate with flat
head screws or held in a chuck. You can remove the disc with heat
from a torch when you are done. The piece between the work and
faceplate should be slightly smaller than the finished work and
thick enough to give clearance to the knurling tool. JP (14485) |
| JP, This seems to be the only avenue and I
did consider it, but I didn't think that glue would hold up to this
kind of pressure. I'll let you know how it works out when I start
the project, maybe next week. Larry (14487) |
| Someone else here
did the face of some discs and held them with glue. Doing the edge
and knurling them will probably require the added pressure from the
tailstock. JP (14503) |
| They do make a
knurler that is hand held. It has knurling wheel on both sides. The
pressure is into the part, rather than side pressure. I have used
one before. They work good. Tom (14530) |
| Cutting HSS
|
| I just
bought a bimetal blade for my bandsaw. I need to cut some HSS cutter
blanks for cutters in my boring bar. They are 1/8" but I would also
like to cut some other blanks that range up to 1/2".Do you think the
blade can do it without destroying itself? I also have a Dremel
cutoff wheel. Would that be better?
Tom (16679) |
| Use the abrasive
wheels, the tool blanks are harder than your bi- metal blade. (16680) |
| Tom, The 1/8
blanks can be scored with an abrasive disk in the Dremel, then
snapped off by holding one end in a vise and the free end in an
adjustable wrench and snapping off. Some folks wrap the bit in heavy
paper, put it in a vise with the score just above the jaws, and hit
it with a hammer. Overkill for 1/8 inch blanks, but about right for
1/4 inch ones. I grind most of the way through on a bench grinder
(around 1/4 to half way through on each side) rather than use up
dremel abrasive disks, the little bonded disks aren't cheap when you
snap 10 of them to get through a single cut and the reinforced disks
wear fairly fast for this sort of use. Once you get past 1/4 inch
sizes you will need the reinforced rather than bonded abrasive disks
if you decide to use the Dremel. The little benchtop cutoff saws use
this style of disk, but not all Dremel dealers stock them. Auto
parts places also have them for use in air powered cutoff tools,
just the thing for some exhaust work when conditions or nearby
things prevent the use of a torch. Bimetal blades are good for
plenty of things, but this isn't one of them, sorry... If you try,
odds are you'll strip a few teeth at first, then the rest will
follow shortly thereafter. One of the downsides of bimetal is that
once you strip a few teeth the rest don't last long. You'll be out
the blade and still have uncut tool blanks to deal with. When I have
to cut 1/2 inch blanks and want minimal waste I use a larger cutoff
saw with a 14 inch disk rather than grinding in on each face with
the bench grinder. Usually burns the steel at the cut zone, so you
either use just the uncut end or grind off around 1/16 inch at the
cut end to get back to good steel. If your can cut the blanks with a
file/hacksaw/bandsaw, the blanks must be some low end unknownium/importium
blend of steel, not real HSS. A quick check for the "Can I cut this
stuff on my bandsaw" question is to try an old file on the material.
If it cuts easily go ahead and slice it up. If the file snags and
scratches but cuts a bit with heavy force it's probably too hard. If
the file just skips over the surface it's too hard to cut with a
bandsaw. You can also test with a hacksaw, if that won't cut the
material neither will the bandsaw. Stan (16681) |
| Tom: CAN'T Cut
toolbits with bandsaw. You can use Dremel Tool with Cut-Off Wheel.
Ron (16682) |
| Cutting/coolant solutions? |
| I did see where someone
mentioned WD-40 for aluminum and found it works very good. Someone
mentioned using a citrus cleaner, does that work well and on what
types of metals? I have a gallon jug somewhere that I bought where
you mix it with water. I tried it and stopped using it because of
the possibility of rust. The recirculating pumps seen in shop photos
are simply not practical for the home shop. At least for me anyways.
What works for you? Joe (18702) |
| I always use
Kerosene or in a pinch diesel fuel for machining aluminum. Small
cans of cutting and tapping fluids are available at all industrial
suppliers. Lubricants don't always work well for machining as
sometimes they defeat the purpose by their very nature. I found
cutting fluids work much better than say WD40 for lathe and bandsaw
work on metal. Paul (18705) |
| I use
kerosene for cutting aluminum. Kept in a small lab wash bottle, you
can squirt into bores or just dribble a bit on the piece being
turned. At $1.60 a gallon or so, it's cheap. Downside is that it
smells pretty bad. For steel I use heavy thread cutting oil, applied
with an acid (flux) brush. A weighted bottle with a 1/2 inch hole in
the lid holds the oil. If it tips over, very little oil runs out.
The hole holds the acid brush, while leaving little room for swarf
to enter. Tapping is usually done with TapMagic. Stan
(18707) |
| Plain old plumbers
dark threading oil from the hardware store works for me. It is too
heavy for tapping small holes and buy the small cans of special
fluids for that job. John (18713) |
| For "heavy" turning
on my 9 inch I use the same plumbers' cutting oil, but have it
diluted about 50% with kerosene. Somebody at GE recommended that to
me 35 years ago. Better yet, in my opinion, is to use carbide
cutting tools -- then most if not all things can be turned dry. No
mess, no stink up the shop OR the house. For small diameter drilling
and turning I use Winbro Tap-Free. It seems to be some sort of
chlorinated solvent, possibly containing beeswax. Steve
(18731) |
| Cutting
urethane |
| I have 3" dia. urethane wheel on a 1" plastic hub
(think rollerblade wheel). How can I cut a half inch off the dia.?
Dremel in tool post? Right now I don't have a spare to experiment
on. I may have to buy another to practice on. Larry (20283) |
| If you want
to cut the 3" wheel down to 2 1/2" use straight forward MS- 101. If
the piece is pressed onto a shaft or has a hub as you say, just use
a sharp tool with a very acute rake. Ron (20284) |
| The
machinery handbook calls for 200 to 300 ft/min speed and zero top
and side rake and 10 to 20 deg clearance angles. HSS tool. It is a
pain to deal with. It needs a lot of power and a sharp tool. Low
clearance and it binds, incorrect rake and the tool moves the part
like a corkscrew. JP (20293) |
| JP and others,
I did the job with a Dremel (toolpost)
grinder. Worked great. Larry (20294) |
| Freeze it hard, before machining it. Gary (20295) |
| Same Speed
Same Feed Different Cutters |
| I'm trying out some
carbide cutter bits. Some Grizzly TCMT 32.51 uncoated 60 degree
inserts and some TIN Coated TPG 322's. I laid the 322's to a 7/8"
stainless bar at .005 feed and .005 depth and turned a baby butt
smooth finish. Then came the uncoated import insert at the same
rates and it felt like 2 days of rough beard growth. I'm sure it
could be smoothed up, but it's amazing the difference in cutter
finish quality. Has anyone out there come up with a good source for
coated inserts? (21885) |
| Its easy to forget
that the turned surface finish is effectively replicates the surface
finish of the cutting edge. So if the edge is not really smooth and
continuous neither will the surface be. Sticky materials like
aluminum really show this up as slight imperfections in the tool
edge act as an open invitation to material build up on the tip.
Naturally any dings, scratches or imperfections in the edge will not
be quite as sharp as the rest of the tip and build-up is always more
likely on a blunt tool. Blunt tools, as we all know, tear rather
than cut the metal which is bad for finish. There is no hard
dividing line between tearing and cutting, its just that the sharper
the tool is the less the tearing and the better the surface finish
until its good enough. The way the metal comes off also affects
things. If you can get it peeling off nicely like an apple skin the
finish is much better. Doesn't have to be a continuous chip, it just
has to peel. Carbide tips are inherently grainy and therefore a
teensy bit rough. The better the make the smoother they are but you
can never get as good an edge as you can with HSS or high carbon
steel (best). In general carbide tips need to be operated with a
decent cut and feed relying on the peeling effect to give a good
finish. The coating process makes the surface finish much better so
the carbide behaves more like HSS and gives you a better finish
especially when used, as we do, at feeds and speeds below the
optimum. Clive (21893) |
