| Help with a boring bar
(Jun 14, 2002) |
Boring Small Holes - Gauging
(Feb 2, 2005) |
| Cylinder boring questions
(Oct 11, 2003) |
Boring bar holder 3/8 (Mar 7, 2005) |
| Boring Bar Holder for SB 9
(Jan 29, 2004) |
Boring a rifle barrel
(Aug 17, 2006) |
| Boring bar and internal threading
(Nov 28, 2004) |
|
| |
| Help with a boring bar |
| I just received a
new boring bar mad by APT. It has a squared off end that fits into
the tool holder of my quick change. However, when I inserted the bar
into the holder I found that the carbide bit was not aligned to the
true horizontal. The front is rotated downward by 5 to 10 degrees.
Since the back end is squared off I cant rotate it so that it is
level. From the operator side of the lathe, the tip that is closest
to the operator is lower than the side that is farthest away. I
would have expected the that the edge would be perfectly horizontal.
Is this the way it should be? If so, how should it be aligned?
Marv (4584) |
| I'm not sure how it works with boring
bars, but with OD turning carbide inserts that can be mounted either
side up, the holder droops them about 7 degree to create some end
rake on what would otherwise be a vertical wall. Do the inserts have
a chipbreaker groove? If so this might be by design. If not, then
it's purpose beats me. Chris (4585) |
| Marv; If I'm
reading your post correctly, the insert is not parallel to the ways?
If this is the case, you're correct is thinking that the insert
should be "flat", with the tip on the centerline of the tool in most
configurations. If this is a Tri-Lead style bar, double check there
isn't some crud under the insert or cartridge, that the cartridge
screws are tight, that the shim and chipbreaker are in place, and
that the insert hasn't ridden up on the beveled edge of the
cartridge. I guess this could be a negative rake boring bar, which
may be made by APT, but isn't a standard item for the mail order
guys (or in the Michigan Drill catalog.) I can't say I know every
tool ever made by APT, but every boring bar from APT I've ever seen
provides clearance and rake via the insert geometry. Lead is either
fixed at 0 or uses cartridges to adjust lead ONLY in the Tri-Lead
series. Dorian makes negative rake boring bars, in -5 degree for
WNMG or CNMG inserts, depending on model, and in -3 degree style for
use with TNMG inserts. Any chance you ordered an APT and got a
Dorian by mistake? Not likely, as Dorian bars are $140 each and up,
but it could happen. Perhaps the setscrews in your boring bar holder
are not square to the body. You can rule out the tool holder by
checking if the insert is parallel with the flat on the top of the
boring bar, or by putting it in a standard toolholder and seeing how
things line up. What model boring bar is this? If you are actually
referring to the lead (AKA front clearance) then the following
applies: If this is a Tri-Lead style boring bar, there are
cartridges used to mount the TPG321 inserts, they cost $8.48 each
from Travers. The cartridges are: CP-5 - positive 5 degree lead CP-0
- zero lead CN-5 - negative 5 degree lead The same clamp and shim
are used with all cartridges. Travers sells these, they are on page
328 of the 2002 catalog. If the boring bar is one of APTs SuperLok
series, which is basically a slotted bar with just a clamp screw,
the insert should have zero degree lead. Stan (4588) |
| It is an APT Super-Lok indexable
boring bar # LB8M. It has a 0 degree lead, but the picture in the
Enco catalog (pg. 269) shows an edge on view (with the center of the
shaft pointing at your eye) that illustrates the cutting insert with
about a 5 to 10 degree angle off of the centerline. Again, looking
at it edge on with the shaft pointing at your eye, the bar appears
twisted along its shank. However, there is no defect in the bar. It
just has a twist in it. The back end of the bar is square So it
appears like this is normal, but how do I set this puppy up? At what
height should it be set and where do I reference its height? Marv
(4590) |
Marv; I'll be
darned! Sure enough, the Enco catalog page shows this clear as day.
I don't have any of the Super Lok bars, and never noticed this the
few times I used them on other folks lathes. It's surprising the ad
and catalog copy doesn't stress that these are negative rake, I
guess the point isn't to allow the use of cheaper negative rake
inserts so they don't push the issue. There are two schools of
thought and reason on setting boring bar height (at least). The
first is to put the cutting point dead on centerline. That works
fine, but it can lead to chatter and dig ins if the bar or work
flexes. The other approach is to set the tip slightly above
centerline, perhaps 5 or 10 thou, so flex tends to twist the cutting
tip out of the cut rather than making it dig in. The one thing that
everyone seems to agree on is to never have the cutting point below
centerline. I usually set the tip just a pinch above centerline. The
downside is that in a small bore you move into heavy negative rake
angles quickly, having the tip above centerline accelerates this, a
case where a tiny bit can be good, any more and it gets ugly fast. I
guess the down tilt allows the bar to fit a slightly smaller bore
without rubbing on the heel of the insert. Pretty neat, when boring
into the hole the actual cutting tip geometry would work as if it
were flat I think, just you get a bit extra heel clearance. Might
just have to fire up the mill and make a few bars to try out! Would
you post how well facing the bottom of a bore works with this bar?
I've always ground my HSS boring bars to have some lead rather than
a flat contact area if they are for an operation that isn't a
through bore, and made my bars that take TNMx inserts slope down 5
degrees to the tip, with around 15 degrees of lead. Stan
(4591) |
| Cylinder boring
questions |
| Anyone on this
group boring small engine cylinders on their lathe? I am looking
expand my shop income doing lawn cycle and jet ski cylinders and
weighing the ways I might have to do this. My mill apparently isn't
appropriate for this I end up with small chatter marks making for
more honing than I wanted to deal with on test runs using a r8
offset boring head and carbide brazed tip, considered the 1/2 in
shank not sturdy enough.? I Considered boring bar machine made for
this but would even then be left in the dark on smaller bores. More
$$ out.. Hmm lathe? I'm sure I could come up with something to make
centering on a faceplate rather easy but I don't have a southbend
yet looked at a few recently gap bed I had a wimpy 9 inch x 1/2 inch
square boring bar with replaceable tip and had BAD chatter, though I
could feel the bar springing badly. Is this only the bars fault?
Asking b/c I also have a 3/4 bar holder for my toolpost and
considered making a solid bar with a 1/4 " tool shank run
perpendicular through it. Would ground HSS tool be enough to cut
cylinder liner? And is this lathe even sturdy enough to do this kind
of work with good finish quality? Gibs are tight, bed straight and
level so I am thinking I wouldn't end up with a bellmouth on the
cut. What sfm and feed should I use if I make a hss tool? Mike (14396) |
| Mike, Get a copy of
'How to Run a Lathe' by Southbend and look on page 91 for boring on
a lathe carriage and page 50 for cutting speeds. HSS cutters give a
nice finish especially when you hand polish the cutting edge with an
Arkansas stone. I wouldn't attempt it on an Asian machine at all,
get the largest Southbend you can find. Make your boring arbor as
large as will fit into the cylinder and hold it between dead centers
on the lathe. JP (14397) |
| I believe the
biggest difference between a proper boring machine and the mill is
that the shaft holding the cutter is being supported at both ends. A
similar result may be obtained by mounting a boring bar between
centers on a lathe and mounting the workpiece on the cross slide.
Dumitru (14398) |
| Boring Bar
Holder for SB 9 |
| Any of you guys got
a plan or sketch for making a post style boring bar holder? You
know, the kind that replace the entire lantern tool post to give you
extra rigidity? (16916) |
| No plans or
sketches but if you are going for a round bar the thing is almost
too simple to need drawings. If you are interested E-mail me off
list and I can PDF format some interesting stuff related to the
screed below. Basically bolt a suitable size lump of steel,
(something like 2 1/2 inch square by 2 inch thick should be a
reasonable starting point for a dual holder) onto the compound using
a stud and T-nut (notes on T nut fabrication below). Use the lathe
to drill a suitable size hole to take the boring bar leaving
sufficient room outboard for a row of three vertical clamping bolts,
1/4 inch is about right size. Doing it on the lathe ensures the hole
is true and on centre height. If you can blag a reamer or boring
head this will make getting a good finish easier. Otherwise its
careful drilling and polish with emery time. Drill the tapping size
holes for the clamping bolts making sure that the bolts run outside
the hole, open out to generous clearance down to a depth just below
the middle of the hole then tap the rest. Cut a slot at mid hole
level through from outside into the hole where the clamp bolts go
and a matching slot a generous 1/8 inch deep into the main body. If
you don't slot both side the bolts wont be able to clamp up on the
bar. Best way to cut the slots is a slitting saw (on a mill) but a
hacksaw gets the job done well enough. Depending on the size of your
boring bar you might want to reduce the top thickness a bit to help
with the clamping. A 1/4 or 3/16 over the maximum diameter of the
hole is plenty. If your boring bar has the tool cutting edge above
the centre line mount the block in the lathe on a four jaw and face
off a suitable amount to bring the tool onto centre. The basic block
works OK but adjusting the tool height is a pain. If you don't want
to alter the angle of the tool you have face it down a bit low and
then shim the whole block up as required. Yeurch! A better idea is
to make the hole sufficiently oversize to accommodate an eccentric
sleeve betwixt bar and block. Make the sleeve a bit longer than the
block with the projecting end a bit larger and carrying some tommy
bar holes or other suitable means of turning so you can adjust it.
Geo. H.Thomas advises that 1/16 eccentricity is sufficient and that
sleeve wall thickness can go down to 1/16 at its thinnest. Slit
through the thickest part of the wall so the clamping action can get
a grip of the bar. If you have several sizes of bar (as Mr. Thomas
advises) then make a set of sleeves to accommodate them in one
holder. T-nuts for the top slide are best made by fixing two bits of
quarter inch steel about 2 1/2 inches long, of suitable widths to
fit the slots, together before drilling and tapping to take the
chosen size of clamp stud. I usually braze the bits together after
drilling for a pair of alignment pins to keep them mutually aligned
during the process (I keep a supply of used "pop" rivet mandrels on
hand as a source of pins for this sort of job) but glue and screw
(two 4 mm ish) works fine. When you want real rigidity make a block,
of the right thickness and having a suitable clamping groove, to
substitute for the top slide thus avoiding all the play in that
component. Alternatively giving the slide a good going over and
ensuring the gib strip is properly fitted before adding a gib
location pin and slide lock (as advised in one of my previous posts)
makes a remarkable improvement in rigidity. If you have a long T
slotted cross slide consider making your boring bar holder to go in
a block style back tool post with the tool inverted to cut on the
back of the hole. Besides rigidity improvements the inverted tool
helps (a bit) with the perennial "hole packed full of chips" problem
which has inspired so much linguistic creativity in multitudes of
workshops over the years. Clive (16917) |
| Follow this
link:
http://www.homemetalshopclub.org/projects/toolpost/toolpost.html
You will find a nice sketch of a homemade tool post and holders. Be
aware that there are some lines and details missing from the sketch.
Mike (16918) |
| Excellent advice on
the eccentric. Much simpler solution than what I was thinking.
That's why I ask. I know that someone out here has spent the time
doing it before and has learned a few things. (16930) |
| Boring bar and
internal threading |
| I have the Williams
2030 Boring Bat holder which takes one of those 1/4" boring bars
with the 90* bend in the end. Where do I replacements? Also, Is
there another type of boring bar that I can use in my lantern tool
post holder? I have seen a few pictures of one in the South Bend How
to Run a Lathe book, but I don't know where to get them. I also want
to try my hand at some internal threading and am wondering what my
options are? Mark (22342) |
| I made a few
boring bars for my 10K from CR flat bar that fits in the lantern
tool post. Mine took 1/2x1 flat. I drilled a hole to hold a 1/4"
square tool bit with the top of the bit on the center line or a bit
higher you can grind down the bit a little. As far as internal
threading I have pics and word for word inst on my SB 10k group.
There is a link in the files section. Bob (22355) |
| That Williams
toolholder will hold a round bar. You take the bolts out and turn
the small piece over. This creates a larger opening. Mine will take
a 1/2" piece of CRS (I think its a 2030). You can make the boring
bar from round stock by cross drilling to fit the cutting tool and
end drilling for the setscrew. If you are the patient type you can
file the tool hole square. I was able to borrow a broach when I made
my 3/8" boring bar with a 1/8" cutter (for making the internal
threads in a collet drawtube). The tricky thing is grinding the
threading tool. The 60 deg angle has to be dead on. With 1/8" steel
its an eye strainer at my age. There is also a company that makes the
old fashioned type of boring bars and some nice cutters for them.
The name is Everreddy or some other spelling, they are on the net.
You may need to fool with the spelling to find them. I have a 3/4"
one for my 13"regal and the thing really shreds metal. RC (22357) |
| I think he means
everede web address www.everede.net
I couldn't find the old style bars though. They mention them on
their site but it looks like they now just do the indexable type of
bar. John (22359) |
| They are working on
the website "slowly", but the nice gentleman at 800-621-5486 assured
me that they still make the original boring bar style. The link on
the website for the original style bar takes you to a metric
converter gizmo. RC (22364) |
| Boring Small
Holes - Gauging |
| The recent posts on
top slide setover got me to thinking about the problems when boring
small holes when you don't have a set of bore gauges at $40 - $50
each. Using a piece of drill rod of the size of hole required, or
the next largest, turn a taper with the cross slide set to 2.86 deg.
A 1" taper will get you 0.1" smaller at the end. Loctite a sleeve at
the start of the taper so when the plug is inserted to the hole
measure the distance from hole to sleeve, the hole diameter will be
1/10th smaller than that measurement. As we don't all have sine
bars, mic the small end of the taper and the shaft size and assuming
a 1" taper mark the taper gauge with that ratio. Almost certainly
not a new idea, but new for me and maybe some of you. Bernard R
(24664) |
| That is a good and
effective trick (tho' not one I use nowadays as I have bore gauges).
However I'd tackle the job a bit differently. Depending on your
equipment, experience and target application differently may or may
not more appropriate. Rather than trying to set the top slide over
at a precise angle I'd work directly off the gauge blank with a DTI
to get a reasonable length taper covering an appropriate range of
diameter. Bernard's suggested 0.1" per inch of longitudinal feed is
good to aim for but I'd not get stuck on shooting for an exact
value. Just make sure you know what it is and that you haven't got
to work with stupid numbers. Don't forget that the cutting feed of
the angled off top slide is along the side of the taper but the
gauging action is via longitudinal movement (i.e. straight down the
axis). I know a man who did! More trigonometry. Sorry. If you are
using drill rod for the gauge fix it into a larger diameter carrier,
which will form the stop step, before you start machining. For a one
off I'd make life easy with a decent FC steel and handle the
finished gauge carefully. Start the gauge at the small end with a
short parallel stub to make it easier to judge when you have it
entered true. Machine the taper so it goes a bit bigger than the
final hole size and machine the stop step integral with the rest
taking great care to make the step exactly at right angles to the
axis. Choose the "bit bigger" amount of taper so that when you get
the bore to size a drill shank of suitable size will just slip
between the step and the end of the bored component. 1/64th is
about 15 1/2 thou so, if you are respectably close to Bernard's 0.1"
per inch taper, it only takes patience to work to a thou on diameter
using drill shanks to gauge how much further it needs to enter and
the usual cigarette paper or 1 thou feeler "gauge grab" indicator.
Drill shanks are excellent, and often overlooked, precision gauging
pins and every ones got a set too. Practice the boring on a bit of
scrap first. You don't actually need three hands, putting a centre
in the gauge shaft at the big end so you can use the tail stock to
support things helps a lot. If you've not done this before draw a
big picture and write it all down, neatly. If you expect to do much
boring its worth making a set of conical bore gauges for roughing
measurements (especially if you have a taper turning attachment and
can make them longer). Choose a suitable taper and graduate to
taste. For a really swish job get hold of some of the narrow, stiff,
scales used on ruler type depth gauges and let them into a slot
milled on the side. You can get commercial sets using tapered steel
rules but the ones I've seen were either flimsy, badly marked or
expensive often all three! Clive (24685) |
| Boring bar
holder 3/8 |
| Any one no of a
link to make a 3/8 boring bar holder for my 10k. I would like to use
those 3/8 boring bars I'm very new at this and seems to me this is
some of the newbies first project. (25794) |
| This is an
excellent question, and easy to do. Through the years, I have kept
tweaking a square tool holder that was easy to use and where the
tool was always on center, or easy to get on center. The tool you
need to get started in the right direction is to bolt a piece of
steel, cold rolled or hot rolled steel is fine, a piece of brake die
is excellent, but don't gold plate it, use what you can get easily.
Start out with it being 2 or 2and a half inch square and high, would
be good, but you want to bolt it down to you compound solidly with a
good 3/8 or 1/2 inch bolt. Square it up with the spindle, put a
drill chuck in your spindle hole. Now put a center drill in the
chuck, center drill your block, then lead drill and finish drill
with a 3/8 drill or reamer. Now when you slide a 3/8 inch boring bar
in, it will be on center. All you need to do now is add threaded
holes through the top to hold the bar in place. If you want to be a
little fancier, and you have enough block you may saw a slit in the
block through the center of the hole, providing a split block. They
add a cross hole, 1/2 inch hole, threaded in the bottom part of the
block, below the split, and clearance in the top part. This system
is kinder to your bars and you won't need a flat ground on them to
hold them in place. Through the years I have saved my dull end mills
that have a 3/8 inch shank, especially the long ones, and use them
as boring bars. You can even use a new end mill since you are going
to cant the block slightly to provide side clearance, you will only
be cutting with a single edge. You can sharpen them easily by
yourself and proved the rake you like grind lead on them or whatever
you like. Don't let them tell you that you need tungsten carbide for
everything. It is a wonderful material, but good high speed is
easier to use and should probably be the backbone of your home shop.
Bill (25798) |
| For tooling ideas I
strongly recommend 'The Model Engineers Workshop Manual' by the late
Geo. H. Thomas, available from
www.wiseowlmagazines.com among
others, besides being a world class engineer the quality of his
work, as seen in the various photos in the book, is truly
inspirational. He has a whole chapter on boring tools and holders.
For me brazed carbide boring bars are the pits, they chip far too
easily and can't stand any form of interrupted cut. HSS meets all my
boring needs. Bernard R (25801) |
| Boring a rifle
barrel |
|
Does anyone on
the list know how to bore a rifle barrel on a lathe? With a long
drill bit I suppose, but how do you keep it going straight through
the stock? Mosby |
|
Thanks for the
link Marq. It was perfect with all the information I wanted to know.
Mosby |
|
Check out this
links.
http://www.shilohrifle.com/
Watch the video shows how Shiloh Sharps makes their Rifles.
Bob |
|
Mosby, I
bought this book from Lindsay about making barrels.
http://www.lindsaybks.com/bks6/rifle/index.html
Its a compilation of several texts. Not really about making
them on a lathe but instead making them on a regular barrel machine. |
|
Mosby: Glad to
help. It seems clear that machining a gun barrel to modern standards
requires a custom boring machine that feeds coolant through a
specialized "drill". A short barrel (e.g., 4-6 inches) should be possible using
progressive reaming after drilling. But a long (rifle barrel) seems
pretty challenging. Marq |
|
It has to
humble one to realize what the gunsmiths of the 19th century were
able to due! Chris |
|
Interesting...
Anyone have any good pictures of one of the barrel drilling rigs? I
guess I still don't understand why the drill wouldn't wander off
center. Does the bushing travel down the inside of the barrel? Mark |
|
I have rifled
a barrel before. The barrel was drilled before and one of the lands
of the rifling was messed up. I drilled it larger, as it was for a
wheellock to about .69 caliber I think. I used a manual machine to
riffle it. In the old days they used a square bit reamer to smooth
the bore. They are quite fun to use. You use a strip of paper to
adjust the cut. The reamer is a square cross section of steel and
one edge is sharp. A 1/3 round of wood is one the bottom and between
them is the shims of paper. One trick I use to try and get some
amount of a striaght drilling is to bore about 1/2 to and inch of
the bore to the size of the drill. This pilots the drill and it
doesn't walk and drill of center as bad. If the part or 'barrel'
needs the bore concentric, then I have extra stock on the OD. After
the first drilling, then I'll turn the OD concentric to the bore.
Once the initial bore is drilled, usually the following drills will
follow that hole, is their drill point is even. I have seen the P&W
machines. I remember them being around 20 ft in length or more. I
think they cost about $50K or so to build during WW2. That was the
cost of a P-38 Lightning. I think the Mustang cost $35K to $40K. I'm
not sure what they would cost to make new, but I think $250K in
'80's dollars. I will agree (with my limited knowledge) that
turning, milling or fluting the outside of the barrel warps or
distorts the bore. Tom |
|
Here's a link
to a home made rifling machine-good info BTW.
http://lautard.com/rmv.htm
Malcolm |
|
The only
information on this web site is that it will cost you (USA
residents) $95.00 to get the information on how to make this version
of a home made rifling machine. Questionable 'good info'. George |
|
Firstly, note
I know nada about rifles. I was recently faced with a similar task :
needing to drill about 14" x .125 through drill rod. I sourced out
www.deephole.com and they
quoted a price that (considering my back was against the wall)
wasn't that bad. |
