| 8" 3-jaw too big for a 10L?
(Feb 19, 2003) |
About 3jaw self
centering/runout (Mar 13, 2004) |
| 3 jaw chuck sprung? (Mar
6, 2003) |
3vs4 jaws (Apr 17, 2004) |
|
Small 3-jaw chuck (Apr 6, 2003) |
Adjusting a Buck 3-jaw Chuck (Jun 27, 2004) |
| 3
Jaw Chuck for SB Junior Lathe (Jun 16, 2003) |
New
3 jaw chuck runout (Feb 4, 2005) |
| Do I need to keep my 3 jaw
5" scroll chuck? (Aug 14, 2003) |
More 3-jaw chuck questions
(Feb 6, 2005) |
| Anyone use the Bison 3 jaw chuck?
(Oct 31, 2003) |
3-Jaw Vs. 6-Jaw (Feb 8,
2005) |
| 5"
or 6" -3 jaw chuck (pros and cons) (Nov 20, 2003) |
|
| |
| 8" 3-jaw too big for
a 10L? |
| I have a 1942-era
10L and currently have an 8" 4-jaw Buck and a 5C collet setup. I
really want to get a 3-jaw self-centering. I know the common wisdom
is to go no bigger than 6" on a 10" lathe, but would an 8" really be
a problem? Remember, we're talking about 3-4 hours usage per MONTH.
I love the hobby, but have the same time constraints as many.
Wallace (9403) |
| This depends a lot on what
you're planning to do, but I would go for the 6". I have a 6" 3 jaw
on my 11" SB and 99% of the time its fine for the general
prototyping and maintenance we do here. I got an 8" 4 jaw and when I
need more capacity than the 6" has I pop on the 4 jaw. Keep in mind
that a 8" 3 jaw weighs more that 40 pounds. They're a pain to be
taking on and off all the time. I just bought a new lathe that came
with a 8" 3 jaw and I've already mashed my finger once just moving
the chuck around. I'll probably buy a 5" or 6" 3 jaw for it and it
will probably see most of the usage, with the 8" only when I need
the extra capacity. The 8" 4 jaw chucks aren't as thick as the 3
jaws so they don't weigh as much so there not as much of a pain to
mount, demount and store. If you're buying one, stay away from the
junky Chinese ones made out of radioactive steel. Don't go any
cheaper than a Bison chuck. Paul
(9404) |
| I
have had an 8" 3-jaw chuck on my 10L for years. I only took it off
a week ago because of the exchanges about stuck chucks. No problems.
Dave
(9408) |
| 3 jaw chuck sprung? |
| Just got my 10k up and running. Love it. Hoping not to loose
a finger. Possible problem: had a 5/8" x 6" piece of CRS chucked
up to try one of Guy Lautard's projects. While trying to indicate
the stock, I found top center over one of the jaws to be about .009
more than 180 degrees opposite that spot. One friend has suggested
that the jaws may be "sprung." Consensus here? steve
(9641) |
| If
the CRS you have is in fact truly round, it should be a few things.
First off, loosen the chuck and turn the test bar 180 degrees, and
see where the 9 thou high point is. If it's now between the other
two jaws then you know it's the rod. If not... Could be a sprung
chuck, could be a few other things too. Might be a bit of swarf on
the spindle threads or jammed in the chuck threads. If not, Chuck up
a couple of different diameters, clock them, and see if the error is
pretty constant. Try snugging the jaws to differing amounts, from
snug to tight, see if the runout wanders around much. The jaws could
be worn, sprung, the spiral or teeth on the rear of the jaws could
be worn, there could be swarf in the chuck, it might even be a
poorly fitted back plate if this is a plain back chuck. I'd take the
chuck apart, clean well, then mount just the backing plate on the
spindle and clock the boss. If that has darn near zero TIR (as it
should), check if the boss is tight in the recess on the chuck.
Wouldn't be the first time one was poorly fitted, or intentionally
fitted loosely to allow a "poor mans Adjust-Tru" sort of setup. If
it fits loosely, mount the chuck and just gently snug up the
mounting bolts. Secure a bit of clean shaft in the chuck, and clock
it. Tap the chuck around for lowest TIR, and snug up the mounting
bolts. If the boss it tight, then just mount up the chuck and see
what sort of TIR you get. If the jaw faces look badly worn or bell
mouthed, then either grind the jaws in place and loaded, as
described on Scott Logan's page, or get a new chuck. If the entire
chuck is sprung or completely clapped out, you'll just drive
yourself nuts trying to work around it. Stan (9642) |
| That's a lot
of run-out for a small 3-jaw. Have you checked to make certain
there's no dirt between stock and jaws? also, the stock itself might
be a tad out of round and you might try loosening up the jaws,
rotate the stock a bit and re-tighten. also, sometimes, if you push
the base of the stock against the face of the chuck and it is not
exactly square, the jaws will clamp the stock at a slight angle. Try
closing jaws with the stock away from the face of the chuck and try
rotating it back and forth while closing the jaws. If all this
doesn't work, then you might have a jaw problem. Take the jaws out
and clean the scroll. I use an old toothbrush narrowed a bit to get
into the slot. I've been told not to use air to clean it since it
might blow swarf into the inside. The toothbrush works well. Clean
the jaws themselves, use a bit of oil and reassemble making sure the
jaws go into the right slots in the right sequence. I recently did a
lot of boring and a lot of crap got thrown up into the scroll and I
had to do this every time between pieces. Frank
(9647) |
| I pulled the chuck apart and cleaned everything up.
Pulled the jaws out and cleaned the threads. Put it back together
and was still out by 9-10 thou. Tried rotating the stock 180
degrees, it was still out with the jaws in the same place. In other
words, it's the jaw. The one opposite the chuck key spot. The chuck
is a 5" (I think) Cushman with a back plate. How much should I
expect to pay to replace it? I'm assuming I just need a plain one to
bolt to the back plate? steve (9688) |
| Steve You can try
grinding the jaws. I have been able to bring a three jaw to as close
as 2 thousandths. You need a heavy ring to preload the jaws. True up
some tube stock or other heavy piece and grab it on the outside of
the jaws. I then use a toolpost grinder and power feed in at slow
speeds taking less than a thousandth at a time. The larger the
grinding wheel the larger the radius groove in each jaw. My favorite
tool is a very heavy duty die grinder from Sears. They have a mount
to attach it to the lathe and use it as an internal toolpost
grinder. I use a 1/2 or 3/4 inch wheel. It takes about 20 minutes
and the check runs amazingly true. max (9689) |
| It's sort of
unlikely that the backplate suddenly goes bad - I doubt that the
previous user would have put up with that much runout. Before
getting
a new backplate, if you really think it is the source of your
problem, why not rotate the chuck on the present backplate and see
if the runout changes? Betcha that you'd be better off grinding the
jaws. Frank
(9699) |
| The figure of
.010" on just one jaw is a curious one - too much to be wear on a
single jaw, too little to be incorrect jaw placement. I ran into a
chuck once that had a jaw with that much variation. On close
inspection, it turned out to have a different serial number on it
than the chuck - someone had gotten the jaws mixed up. The only
other cause I can think of is loose fit of the scroll in the chuck
body, allowing a shift toward the chuck key pinion upon tightening.
The scroll should fit the body pretty closely. Agree with Frank -
the backplate is the easiest to check and eliminate as the problem.
Either way, grinding the jaws is the least expensive solution.
Mike (9700) |
| Have you tried different diameter work pieces?
If the chuck is out the same amount on different diameters it would
appear that the one jaw was bad or that, somehow, the scroll plate
was no longer centered in the chuck body. If the error varies with
diameter it would seem likely that the scroll was worn to differing
degrees at different diameters. Anthony
(9706) |
| Before
you do something drastic, a couple things to check. Remove the chuck
from the spindle and check the threads for chips. be sure there are
no chips or metal flakes stuck to the threads or the seating
shoulder. sometimes metal flakes get "welded" to the thread
surfaces
and throw the chuck off. If it still runs out after cleaning the
threads, try to determine the source of the runout by first removing
the chuck from the backplate and check the backplate flange for
runout with a dial indicator. If it runs true then the source of the
runout is the chuck / jaws. Wayne
(9709) |
| Frank, Sorry,
I didn't write clearly. I meant how much
would it be for the chuck. I'm with you, doesn't look like there's
really anything to go wrong with the backplate. steve (9713) |
| I have pulled the chuck apart, checked the
backplate for run out, cleaned everything 'till it was nice and
shiny. The only place anything could be that I can't check on would
be inside with the scroll. Sounds like the next option would
be grinding the jaws. Can one of you fine folks point me to a spot
on the web that explains the correct way to do this (or if you have
time, lay it out for me)? steve (9714) |
| Steve Did you
check to make sure if the jaws were in the correct order? They
should be numbered for the slot they go in, if they were out of
place, that could have been the problem Clint
(9716) |
| See
http://www.loganact.com/tips/chuck-jaw.htm
to start. Do a Google groups search in rec.crafts.metalworking on
"truing lathe chuck" and you'll get a ton of info. Mike (9720) |
| Check the
catalogues- MSC, Enco, etc. for chucks - also Ebay. But I worry
about Ebay - the chucks might be very worn - lately I've had more
and more problems with Ebay on a variety of things. I think people
are unloading crap on Ebay. WARNING ABOUT USED MACHINERY DEALERS: If
you order a used chuck (or anything) form a dealer who is willing to
take it back if you're not happy, make certain you know the terms of
the return. One of these guys takes 3% off the refund (if you paid
by credit card) and tells you that the credit card company does not
refund their charge to him. That is BS. In my business we accept
Visa, MC and AMEX and ALL of them refund their charge if the vendor
issues the customer a credit. I don't begrudge the guy a 3 percent
restocking fee, but he needn't lie about it. Also, the credit cards
do NOT charge 3 percent to the vendor if he's got any kind of
business and if his average ticket is high, as it would be in
machinery, as opposed, to, say, hula-hoops. Frank
(9722) |
| Small 3-jaw
chuck |
| I am trying
to get a 4-inch 3-jaw centerable scroll chuck for precision work. I
have bought 3 different used ones and each had problems, mostly,
they were worn out. Fortunately the sellers refunded my money, but I
think this is telling me I need to get a new one I would like a Buck
or a Bison. Anybody have specific recommendations re either? Are
there any "discount" sources for these things? Frank |
| I just
posted about the Bison on another topic. I have seen them discounted
$50 or so here and there online...I got mine from MSC. I got the one
with removable/reversible jaws. I think most people feel the Buck
is the Rolls-Royce, here, but the Bison four-jaw 6-1/4" scroll I got
shows _no_ runout with the Mitsutoyo dial indicator. The chuck is
made in Poland, and I have seen watches whose interiors are not as
well finished as this chuck. I got the one with the removable
reversible jaws. Kind of big, massive and looks silly on my little
SB Model A, but it runs SO true. They give you two wrench gears
sockets at 180o...that's really handy. Has an astounding top speed
rating something like ~3,000 RPM (Are they NUTS? I mean for a
threaded chuck?). I am glad I bought it last month. Allow $50 or so
for the backplate. Took my time and was very fussy machining the
backplate. Instructions and dimensions are metric, so it took a lot
of mumbling converting the crossfeed numbers.
(10109) |
| I have a
125mm TOS chuck, made in Czech Republic, very similar, and not
overpriced. Scrolls on the key just like silk. I too took immense
care over the backplate, particularly hard as the cast iron one I
bought was full of inclusions. Len (10112) |
| 3 Jaw Chuck for
SB Junior Lathe |
| Does anyone know
where I can find a 3 jaw chuck for an 8" South Bend Junior lathe?
The lathe spindle has 1-3/8 10 threads, not the 1-1/2 8 found on 9"
lathes. Bob
(12024) |
| I have
seen one such chuck on E-Bay in the past three months. I think the
real question is "Where can I get a backing plate for a chuck to fit
this lathe". Do a Google search on +"backing plates" +lathe. I seem
to remember a site which would custom make a plate. My lathe is
also, at the present time, a 1 3/8 - 10. (It is a 9" lathe however)
I am in the process of converting it to a 1 1/2-8. I have two
backing plates. One is on a 5" 3 jaw chuck the other is on a 6" 4
Jaw chuck. One is promised. If you can wait you can have the other.
Finding these is not easy. Without a chuck or a face plate making
them is not easy either. There were several messages about cutting a
10 pitch thread on an older 9" like mine. This may be the same
issue. My lathe came with the 5" chuck. I bought the 6" and a blank
backing from ENCO 16 years ago and had the shop, at the company,
where I worked, bootleg the threads on the backing plate.
Jim
(12030) |
| Do I
need to keep my 3 jaw 5" scroll chuck? |
| Just received
my Atlas 4-jaw 8" independent chuck with built-in 1.5"x8 tpi mount -
other than some surface rust crud in the jaw adjuster threads, very
good, hardly used, condition. After getting a 50 cent stainless
steel brush at the flea market, I cleaned the threads of the chuck
and spindle of my 9" Junior, oiled both mounted it. When the SBL
"How to" book says clean the threads, do it! Those threads need all
of the crud out. The tailstock came with an Acorn brand [almost as
old as sin] 1/2" capacity chuck to which I have added a 3/4"
capacity 18N chuck with MT2 mount. With a MT2-3 sleeve coming soon,
I can use either also in the spindle for small diameter stuff. The
Atlas goes nicely with my Union 3-jaw 6" independent chuck for which
I need to get a mounting plate for. The Atlas weighs around 14
pounds and the Union will be a pound or 2 less with the mounting
plate. Both chucks jaw adjuster screws are 1/4" square holes my ole
Sears 1/4" palm ratchet with extension does just right - I may even
finally get to use my 1/4" speeder after all these years. My
question is: Do I need the SBL 3-jaw 5" scroll chuck with reversible
jaws which came with my Junior? What is unusual about the chuck, the
teeth on the bottom of each jaw are cut oval for either inside or
outside operation. Since I can even use my electric screwdriver on
the two larger chucks, I'm thinking I need the centering accuracy
more than work mounting speed. I don't believe I'll be doing
production work with my 75 year old Junior. Bob
(13364) |
| I have been using my 4 jaw, 8" Atlas chuck on my 9" Model for the
last 24 years. I still have the 5" 3 jaw SouthBend chuck that came
with my lathe but it just sits on the shelf. Gary (13371) |
| What is unusual for either inside or
outside operation. chucks, I'm thinking I need the centering
accuracy more than with my 75 year old Junior. I use the 3 jaw more
than the 4. actually I had the lathe for more than a year before I
got the 4 jaw. 3 jaw chucks often have a longer jaw so you can grab
more on a part. I find when turning long shafts, I use the 4 jaw for
the shorter distance. but, for sheer ease of use, the 3 jaw is my
favorite. And, since I often do all all machining from one end, all
I need it a parting blade and a reverse to face and champher. Use
what you like best, but it is good to have tools in the box for when
you need them. personally, I hate to indicate a part, when the OD or
ID is not critical that it be perfectly concentric. I had to do 40
parts, 2 faces, and bore to diameter. the OD was left as mill
finish. But when trying to use a keyed shaft as a piece of rough
stock and turning the dia to the largest possible diameter, only a
4 jaw will do. Dave (13378) |
| I guess you
never have a need to turn hex stock? ;-) Keep both. Get more. If you
are in the middle of a job and need to do something else, you can
unscrew the chuck and workpiece and put on a different chuck for
that emergency job, then switch back to your regularly scheduled
project. If you have a rotary table or dividing head and can mount
your chuck to that, you can shift a workpiece from lathe to mill w/o
loosing your setup. Also, 3-jaws are great if you will be machining
all important surfaces before removing from the chuck. That way
everything is concentric. Just part-off the workpiece when done.
There are some things that a 4-jaw just can't hold. Same goes for a
3-jaw. Paul R. (13381) |
| Anyone use the
Bison 3 jaw chuck? |
| I'm in the
market for a new chuck for my 1945ish 9" Model A. I've seen the
small (5" or 6") three jaw chuck Bison has (Enco) with a 1 1/2" x
8tpi direct mount. I've also been looking at a small Bison adjust-tru.
I like the light-weight of the direct mount, but I like the
adjustability of the adjust tru. Of course I'd also need a back
plate for the adjust-tru. My main concern with the direct mount is
the fit against the shoulder of the spindle. Anyone used or seen the
direct-mount 1 1/2" x 8? Does it fit the SB 9" spindle OK? The
adjust-tru, with backplate will be more than double the weight of
the direct mount (10lbs vs probably 20-25). Maybe that is reason
enough to use the direct-mount, assuming it fits the spindle OK.
Opinions? mark
(14686) |
| I got one of
those Bison chucks last year and had the same concern that you do
about the back plate going on the 1.509" diameter neck of the SBL
spindle. When the thing arrived it was 1.515" at the neck so it went
on there easily, and barring extreme stupidity on my part will never
get stuck. I got a regular 4" 3jaw for my model B workshop lathe, and
find it very handy. Rob
(14687) |
| I am using the Bison 4-Jaw scroll
chuck, with adapter plate, and love it. Model A, 9". I did a careful
job of machining the backplate and putting in the bolt circle, and
it has paid me back. The plate and chuck combination is a bit heavy
and looks stupid on the little 9", but it runs true, and has been
doing a good job for me for six months.
(14693) |
| I bought two BTC chucks for my model 405 Nine about 9 months ago from a local
large chuck vendor. They're nice chucks but the 4 jaw, even using my
old backing plates, was a monster, over 20 lbs. I called Randy at SB
and, once again, he was patient and took a lot of time- about 15
minutes- discussing this over the phone. He said, without
guaranteeing it, that the weight was pretty much ok as long as it
was running true and assuming the bearings in the headstock was ok.
But I'm the same way-it sure makes me nervous looking at it up
there! Bill (14694) |
| I am using,
almost exclusively, a 5" 6-jaw adjust-tru Bison chuck on my SB9A. It
love it, it works great and isn't too big or heavy at all. It came
with the Bison backplate as a unit. It is what you are calling a
direct mount and has no problems with its fit against the spindle. I
initially bought a 6" chuck but it was too big for this lathe. In
regard to the 3-jaw chucks you mention, it is possible to make an
adjustable backplate to turn an otherwise plain back chuck into an
adjustable "adjust-tru" type of chuck without adding much weight. I
did it with a Bison 4" 3-jaw plain back for my minilathe. I posted
an article a while back on it:
http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/SetTruBackplate/
When I checked this article just now, most of the embedded photos
didn't load/appear and I don't know what the problem is. If you look
at the article and have trouble getting the photos, please let me
know and I'll try harder to fix it. I'm not sure what it would take
to make a direct mount, as you call it, threaded backplate into an
adjustable one, but that is what the original article by Richard Torgersen shows. Rick (14695) |
| Also very useful
with soft jaws bored to fit work, not used collets since then now
more than 1 1/2 years. Boris
(14697) |
| 5" or 6" -3 jaw
chuck (pros and cons) |
| I'm going for it
! A new Bison D1-4 3 jaw chuck. The only thing to decide is 5" or 6"
?? I see that most people are saying the 5" is better suited. Why is
that ? I'm thinking that I will go with a 6". As a foot note, I
can't find anyone in Canada that has a 5" in stock either. So is the
6" going to cause problems for me. Should I wait 4 or 5 weeks to get
a 5" ? Mike
(15100) |
| Mike 6"
should be fine, some think that a 5" is about the correct weight on
the spindle, but my opinion a 6" is fine, I think I would stay with
a 5" or so if using a 4 jaw chuck Go far it if you want. Clint (15102) |
| What size lathe? RC
(15104) |
| You don't
mention what size lathe. On my 10k I use a 6-inch 4-jaw independent
and a 5-inch 3-jaw scroll. that has worked fine with me for about 3
years. A Bison 3-jaw 6-inch is BIG. also it depends a lot on what
kind of work you do. Don't forget that the jaws a longer on a bigger
chuck and they'll stick out more and that can be a limiting feature.
Also, look at bison run-out specs (in the MSC cat, for example).
You'll find the the larger the chuck the greater the run-out. In
other words, smaller 3-jaw chuck are more accurate. I mostly futz
with smaller stuff and have bought a 3-inch, 3-jaw Bison and
mounted it. It centers stock within a thou and is my most-used chuck
now. In my opinion, a 6-inch 4-jaw is good - it will handle the big
stuff and a smaller 3-jaw is useful and light. Again, it depends on
the size of lathe and the type of work you mostly do. For what it's
worth, I like my Bison Frank
(15106) |
| No
replacement for displacement I all ways say. But it makes more sense
to have a big 4 jaw independent. Also watch the over hang of the
jaws, not a big deal when you have them reversed and are going for
maximum dia. But can hit the bed when you are going the other way.
Mark (15108) |
| It's a
heavy 10 with a D1-4 camlock. So the chuck is a direct mount. The 6"
weighs 20 lbs. A plain back with adapter would weigh in at 21 lbs
plus another 10 for the adapter ! A 5" plain back is only 10 lbs
plus 6 lbs for a grand total of 16 lbs. So that's only 4 lbs
difference. One plus for the bigger chuck is a bigger hole. I don't
know what to do. I want to order this thing Monday. Mike
(15117) |
| I have 6"
3-jaw and 6" 6-jaw scroll chucks for my heavy 10 (2 1/4" x 8
threaded spindle), as well as a 6" 4-jaw independent chuck. I don't
see any problem, and, as you say, the extra flexibility is nice. I
think there is a big difference between hanging a 20+ Lb chuck on a
heavy 10 (which is in many ways a shrunk 13") than for instance on a
10K or 9" lathe, with their much less substantial spindles and 1
1/2" x 8 threads. Frank
(15120) |
| Go with the
6" If your like me and do not know what you may try to machine you
will really be kicking yourself one day when you need 1/8" bigger
and your chuck cannot handle it. If you plan on doing a lot of
really
small parts think about a collet setup someday. it much more
accurate. (15123) |
| About
3jaw self centering/runout |
| Tonight I was
doing a few dial tests on my lathe and noticed my test bar (very
high quality steel - straight as an arrow) had a bit of a wobble when
clamped about 3ft out from my three jaw chuck. The variation became
less as I moved the dial further toward the chuck till I was left
with about .2mm runout about 25.4mm from the chuck jaws (an inch for
you Imperialist dogs lol). This had me puzzled, so I went through
what I though were logical tests to find where the error lay. I
dialed the rear face of the chuck - all square. I dialed the front
face of the chuck - all square( at least 'twen the jaw slots). I
dialed the edge of the check - all square (within reason due to the
usual lumps and bumps. This left me with the options that it was the
jaws that are out, or alternatively, the scroll holding the jaws.
Here's the meat of the message, how does one fix this problem? If its
the jaws then finding the odd one out will be difficult enough let
alone filing it. I wouldn't have a clue how to grind all three at
once reliably. If its the scroll, then I guess I have a dead-ish
chuck suitable for rough work only. I have cleaned the chuck inside
and out to make sure there is no swarf or other crud causing the
problem. Any ideas or advice ( short of buying a collet set - I'm a
cash poor SOB). Garry D
(17724) |
| Using my
rudimentary conversion to "real dimensions" 0.2 mm should be about
0.008 thousands. This is a bit more runout than I would like to see.
This portion could be the scroll If you grab the far end of the bar
does it wobble on the indicator? The fact that the run out decreases
as you move toward the chuck indicates that the jaws may be clamping
at an angle. not parallel with the bed. I have a similar condition
with a Buck 6 Jaw I got used. Some of the Jaws only clamp at a point
and not over the length of the jaw. If the bar wobbles this (not
parallel) is the most likely reason. The solution for this is to
grind/turn the jaws on the lathe. To do this you need to make a
fixture which sets the jaws under clamping tension but is clear of
of the jaws. There have been several discussions of this process.
Try to search the archives an look for +chuck +jaws However I am
concerned about the 0.2mm run out at the chuck. This portion could
be the scroll. Grinding or turning the jaws will correct this ONLY
for the diameter at which you grind and could increase the runout at
other diameters. Check to be sure the faces of the jaws are smooth
with nothing which would cause the runout. Jim B.
(17725) |
| Before you panic try a different diameter test bar. Really check for
swarf imbedded in a jaw or scroll (sometimes you can't see the swarf
chip, but find it with a scriber or something like that) Of course
the obvious is to make sure the jaws are in the matching slots. If
your chuck has three holes or sockets for the chuck wrench try all
three to see if anything changes. If you are stuck to using that
chuck don't despair just mark your work so it always goes back into
the chuck with same jaw on the same part of the work. (A good idea
with any three jaw) There have been several posts on grinding chuck
jaws on the Logan list using plates with holes, putting pins on the
face of the jaws etc and grind from a tool post grinder. This all
depends if you are making brass stove lid lifters where a 100 thous
out would not be noticed or making rifles or IC engines. I have seen
three jaws used in job shops where the old Bull of the Woods always
puts a tin foil shim under jaw #2 of that old beat up chuck.
(17731) |
| Thanks to Capipio
for sending a URL to me by priv mail.. I may be able to rescue the
chuck yet. Garry D (17732) |
| I tried
the suggestions that were listed, except the boring of the loaded
jaws. I replaced my "inners" with my set of "outers" and came up
with the same problem... different size bar and all ( the test bars
I'm using are 1/2" to 1.1/4" high grade polished steel from junked
laser printers) I still came up with the wobble. Now I guess its
still possible that both sets of jaws are a bit "out" as the
"outers" showed less runout. I cleaned the scroll by dousing it in a penetrant/lubricant like WD40 ( if you blokes know what that stuff
is), leaving it for a min or two then turning it all the way round
plenty of times while blowing it out with 60psi from my compressor..
so its got me stuffed what's going on. Unfortunately I don't have any
other Amateur Machinist mates anywhere within cooee who I can borrow
a chuck from to see what's going on... I might have to see if my
local machinery supplier will trust me with a known "good" chuck and
go onwards from there. One other thing too, the taper on the spindle
is MT3 (its a Hercus 9" which is basically a 40's or 50's(ish) SB
copy) and I put in an MT3 sleeve and it ran so true the dial
indicator moved about .005mm ( erm.. 0.0001969" for you antique
non-metric ppls :O] ). So I'm sorta stuck for now at least till I
can get a "trued" chuck from somewhere. Garry D (17733) |
| There are some things that go on with 3-jaws.First of all there is
the usual tip wear. A loupe and small square will help you see the
wear most jaw ends experience. Older chucks almost always have this
condition. Further back towards the chuck body, the jaws look a little
better. Take some .2mm shim and chuck your bar. Now slip the shim
between jaw end and bar. Notice it slips in about 1mm towards the
chuck? The other is scroll wear as already mentioned. Catboat is
correct in his estimation. You may want to live with the
problem. Grinding the jaws requires a spacer the jaws bear down on
while you use an ID grinder to true them up, OR try this: Get a piece
of brass 7"long and 1" in dia. On one end turn a center hole for the
tail stock. On the other end carefully turn a taper so that it is
longer then the jaw and flared bigger at the end. Put a larger center
hole in here carefully. Dog the shaft so the tail rests on the
compound slide. TRANSLATION and visualization: The brass shaft is
about to become a lapping tool. It will be centered with the tail
stock, and another center in the bore. The flair of .010(English
doggie measure!) will be at the back of the jaw. The dog will be
placed towards the tail stock. The tail resting on the compound
slide. The idea is to match the back of the jaw to the front; hence
the flare. The American Machinist article (circa 1900) advises you
pound some lapping grit onto the flared lapping end. They don't say
just how this was done but this may help. Sprinkle or pour some
emery#220 onto a hard surface. As you roll the lap over the grit, work
the bar over with a rawhide mallet; kinda like a politician caught
with his hand on your wallet...on second thought not THAT hard! Cover
the bed under the chuck. Put the device 'tween centers. Fire up the
lathe on slow speed. You have already screwed the chuck down so the
first jaw just touches the lap. Continue lapping dripping some oil on
the work. As you progress keep screwing down the jaws until you have
full contact. Re-charge the lap if necessary. The beauty of this
little kink is that you use the inaccuracies of your lathe to
correct them. Now this won't cure a worn scroll. It will clean up the
jaw taper we all have. Someday when you get rich, buy a buck chuck
what got adjustable jaws. I keep my own chuck trammed in once a month
to .0002 t.i.r. The other thing you can do is get hold of a 4-jaw
chuck. It takes a dial and some practice to use but it can be a very
accurate way of chucking. Ron
(17734) |
| One more place to look before taking a chisel
to your chuck. If it is a screw on type of mounting really clean
with a scriber the threads on both your spindle and the internal
threads in the chuck. Swarf can be in the root of the thread and is
the same color as the steel and flushing with solvents will not take
it out. Some chucks are threaded in the body to fit directly on the
spindle while others have a back plate casting that the chuck bolts
to. If you do have the screw on type of chuck make sure it fits
fairly loose on the threads but fits closely on the register (the
portion behind the threads that is raised a bit from the thread
diameter) If your chuck has a back plate remove the back plate,
screw it on the spindle and take a truing cut across the back plate
using your lathe of course. Backing plates for chucks, face plates
and drive plates even if new should be trued up on the lathe were
they are to be used.
(17759) |
| 3vs4 jaws |
| I still need some idea if a 6-jaw is at
all worthwhile, maybe just overkill for a hobbyist? I realize a 4-jaw
is far more versatile but my 4-jaw is a monster 10" and won't hold
tiny parts at all. I like it mind you but needed something in the
3-jaw type as well. I have a fairly good set of collets but it
requires switching over to that system each time when I want to use
them so a 3-jaw again seems to be a nice thing to get. My wife
doesn't go for tool purchases too often so I am going to get the
3-jaw while it's cool with her g it.
Tom (18471) |
| I think
the advantage of the 6 jaw chuck is that you can grip thin wall
stock with less crush. You have 6 contact points instead of 3.
Practice hold pipe jaw worthwhile, maybe just but my mind you good
set of when I want wife doesn't while it's can swing and don't Buck
with chuck can be reversible jaws depends on retiree, I time fooling
spacer. I use my month. My usual other point out, but if merely a big
back. There is much will give adds it's own. (18487) |
| It is
possible, and not really that difficult to turn a standard chuck
into and adjustable chuck. I did it for a Bison 4" 3-jaw for a minilathe which uses a bolt on backplate:
http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/SetTruBackplate/
An article in Metalworking, The Best of Projects in Metal, Book One,
titled "Greater Precision for Scroll Chucks" by Richard Torgersen
shows how to do it for threaded spindle backplates. I used this
article as initial guidance on building mine, and the project was
quite easy. I'm not sure how much more difficult it might be to do
if the threaded spindle as in the Torgersen article, but it is a way
for you to get the adjustable function of a Set-Tru chuck without
the high cost. BTW, I have an Set-Tru Bison 5" 6-jaw chuck and I
love it. I use it almost exclusively over the Kitagawa 6" 3-jaw
chuck that came with my SB9A lathe. The one place I've found the
3-jaw is better at is holding stock tight so it doesn't spin in the
chuck jaws under extreme loads. I've only found this to occur when
threading using a tailstock die on larger diameter threads. The
6-jaw just doesn't seem to have the same gripping power in this
circumstance. Other than that, its really great. Rick (18488) |
| Rick,
I have seen that article before but this is about my trying to
convince my wife that an adjust- tru chuck is a good deal. If I
showed her that article she would be happy if I get a standard 3-jaw
:-).I'm still shooting for that adjust -tru even if it's not in "as
new" condition. I have a lot of advice now and still think if I can
find one I will try to get one. Tom (18490) |
| Adjusting a
Buck 3-jaw Chuck |
| I just got
my Buck 3-jaw chuck from Plaza Machinery. I have never used one of
these before and would appreciate if someone could tell me how to
properly set it up. I see the four adjusting screws on the side but
do I need to loosen the back plate before doing the
adjustments? Directions to a web site with instructions would be fine
too. One more thing, I also got a used face plate. This is also a first
for me. Would it be correct to take a facing cut to match it to my
spindle or should it be fine as is? Tom (19810) |
| I
would be inclined to take a very light "dusting cut" or two on face
plate to just clean it up. As to the mounting plate for the chuck,
same would apply to corresponding surface for max results. As to the
four radial screws, no real need to monkey here, as this is why they
are there. As to procedure, chuck up a large dowel pin or other ground
piece and keep squeaking adjustments until your dial indicator shows
you have arrived at your desired concentricity. Also would leave a
very slight drag on lock screws to help hold things until ready to
'LOCK HER UP". Lee
(19811) |
| New 3 jaw
chuck runout |
| I've been working
hard to learn this craft on my SB heavy 10 for the past year. Most
work has been using an older 4-jaw chuck; beat-up, but I can still
get decent accuracy. I recently decided to treat myself to a brand
new three jaw chuck to speed setup on low precision work. I accepted
delivery of a Bison (Poland), 3-jaw chuck this evening, with a
threaded backplate mounted by the factory. I couldn't wait to try it
out. Much to my disappointment, mounted on my lathe the chuck has
about .004 runout. The manual states admissible runout is .003mm,
which I believe is .00012 inches. I get about the same amount of
runout when measuring chucked work, on the face of the chuck, and
around the outside perimeter of the backplate. I have removed the
check, checked to see the threads and hub were clean and free of
chips, etc. No change. Since I could get very good accuracy with the
4-jaw, I'm sure the problem is not my lathe, but perhaps an
inaccuracy in the backplate. I was not expecting great precision
here, as many prior posts have spoken to the accuracy problems with
a 3-jaw chuck. But .004 seems a bit much right out of the box. Are
these things adjustable? (Book offers no suggestions) Is there
supposed to be play in the bolts that mount the chuck to the
backplate that I should fiddle around with? I hate to muck around
too much if I have to try to return this thing.
(24819) |
| I think your
best hope of achieving the .02 mm tir is to machine the back plate
on the lathe you are going to mount the chuck on. With use it only
goes down hill from new with a 3 jaw chuck. Or so I have been told.
Nick (24824) |
| I
just bought the same chuck and I love it. I didn't know they
came already mounted, but you really should take that plate off and
cut and fit it yourself. Everyone s spindle is a little
different. Is your spindle or the threads dirty? Does the back
plate come off? Bernie (24826) |
| Bernie: What
kind of accuracy are you getting with your new 3-jaw chuck? My
problem is not dirt or chips in the spindle, so unless there is some
type of adjustment trick, I'll take things apart and machine the
back plate. Always fun taking a chance at ruining a $250
tool. (24827) |
| I
would complain. But first, I would measure the register diameter of
your spindle and the corresponding register of the chuck's backing
plate. If the backing plate is more than .001" larger, then it will
have problems centering the chuck accurately on your lathe. The best
thing is to get a blank backing plate and machine it to fit your
lathe. Webb (24828) |
| I am not that
familiar with the heavy 10. On the 9/10K the backing plate must but
against the shoulder at the end of the threads. Yes the threads must
be clean but they are a guide, The locating mechanism is the
shoulder. There is a small section just before the shoulder where
there are no threads. This section is slightly larger than the
thread diameter and the backing plate must have clearance to ride
over this section. Can you verify that the plate has bottomed? Jim
B.
(24829) |
| Jim B. and
Webb, I can see clearly the shoulder of the chuck where it
mates against a corresponding shoulder of the spindle. It appears to
snug up nice and tight with no gaps. The depth of metal between the
shoulder and the start of the threads is perhaps an eighth of an
inch deeper than my other chuck, so this new chuck probably grips
one fewer thread , but it appears to be to be adequate. I take it
that "register diameter" is the the unthreaded metal between the
shoulder and the start of the threads. I does make sense that if
these two diameter differ by more than the .001 you suggest, there
would be looseness in the fit and fit will be sloppy. Is this
register diameter standard for all 2-1/4x 8 spindles? I'll check
that tomorrow. (24830) |
| A tenth
runout on a 3 jaw chuck? Keep dreaming! What you measure is about
what you can expect. You 'may' be able to improve it some by
refitting it on your machine. JP (24831) |
| Two other
points that almost never come up on this is the fit of the back
plate thread to the spindle thread and the fit to the spindle
register. With factory threaded back plates .004 is about the best
you will ever get unless you have an Adjust-tru chuck or alter yours
into one. The best option is to make a dummy spindle nose that
matches yours as close as possible including the thread fit. The buy
blank castings and machine them yourself to a snug fit on the thread
before you fit them to their chucks. JWE (24843) |
| On any
threaded spindle I have owed, I have machined the backing plate to
that machine.
(24846) |
| First lets get the nomenclature correct. The backplate screws
onto the lathe spindle. The chuck bolts to the back plate. The
quick and dirty way to get the chuck running true is to machine the
*outboard* register diameter on the back plate oversize. Then drill
the mounting bolt holes on the chuck oversize. Mount the chuck with
the bolts snug but not tight. With a test piece in the chuck 'bump'
the chuck until it indicates 'true'. Tighten the bolts (check runout
after tightening and re-adjust if necessary. There was a thread on
this method a while ago but I'll be damned if I can find it. Another
advantage to having a 'sloppy' register between the back plate and
the chuck is that you can indicate each job and (sort of) run around
the fact that three jaw chucks do not reliably maintain a reasonable
runout each time they are used (or each time the workpiece is
mounted). Concerns have been expressed that the chuck may move in
use but I have been using this method for a long time and have never
run into this. Ken.
(24847) |
| I get quite a
bit less than .001 TIR repeatability. Which I am damn happy about
with a $150 chuck! I have a 4 in. #3204 three jaw self centering
chuck. It is what they term Semi-Steel , which is the cheapest they
sell. So yours should really work fine. I personally can t see how
a chuck could be delivered and work that well if the backplate is
not finished on the machine it is being used on. It is VERY UNLIKELY
that the body of the chuck is really out. If you can get it apart
(which it should) it should only really take you an hour or two to
re-cut it, and mount it back on. It took me two hours, taking my
time, and the backplate wasn't even made for my chuck, so I had to
modify the mounting holes. How does this sound? You will be happy
you did it. When I spend another hour or two on it, I have heard
that AFTER getting the backplate right, that micro grinding the
inside of the jaws with extremely light cuts with a toolpost grinder
setup can get in near .0001 or less! Bernie (24848) |
| Please tell
us what you mean by make your own Adjust-Tru chuck plate.
Bernie (24850) |
| If you have
studied the articles posted here and understand what the author is
saying it will be for most obvious what to do
http://groups.yahoo.com/group/mwhints4/files/LatheChucks/
If it is not clear here is a strong hint. Instead of making the
chuck a snug fit on the backplate, leave it about .010 to .020
loose. Then drill three holes for small socket head cap screws
between the three chuck mounting holes in the back plate so that the
heads of the screws once counterboring and tapping are done will
just catch the locating recess in the backplate. You can then
instead of bopping the chuck to center it as has already been
suggested, tweak it to center using these screws and an Allen wrench
similarly to how the high price brand does it. Articles have
appeared in many magazines over the years illustrating this process
and I have seen several excellent descriptions by several others on
this subject over the years on many lists. JWE (24856) |
| I have had excellent
luck mounting back plates to chucks. First, I would mount the new
back plate backwards on the spindle, check for trueness as best
possible, ( even making an accurate spacer ring if needed), then
remove some material from the back shoulder in order to obtain a
maximum or more reasonable amount of thread contact. Then the face
of the new back plate was trued and/or narrowed if needed, then
shouldered to fit quite tightly into the back of the new chuck.
Using Bison 4" and 5" chucks, I obtained .0007 on the 4", and .001
on the 5". Harve
(24857) |
| Could this be loaded into the SBL files section for reference,
please? Mark (24858) |
| Here is a
link to how I made an ordinary 3-jaw into and adjust-tru:
http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/SetTruBackplate/
If the link breaks when it gets wrapped, so you'll have to copy the
part on the second line and paste it onto the end of the first line,
or some other manner to get it to work. I also uploaded it to the SouthBendLathePix yahoo group, at this link, but its not any better
for avoiding the broken link problem:
http://finance.groups.yahoo.com/group/SouthBendLathePix/files/Adjustable%20Chuck%20Backplate/
Rick(24861) |
| This is the
one I was speaking of earlier! JWE (24862) |
| A picture is
worth a thousand words! This is much clearer to me now, I'll have
to try it on my 3 jaw. Excellent web page - easy to understand.
Alex (24863) |
| Actually, in
thinking about it, my article/design dealt with a backplate mounting
different from a threaded backplate. In my case the bolt-on spindle
mount OD was enough less than the chuck OD that there was room for
overhang and screws. For threaded backplates like on our South
Bends, Torgerson's original article (Metalworking, The Best of
Projects in Metal, Book One, titled "Greater Precision for Scroll
Chucks" by Richard Torgersen) is probably better suited. Concept of
the adjusting screws is the same tho. Rick (24865) |
| Set it up
with 4 screws so it can be zeroed in like a four jaw chuck. It's
much easier than with 3 adjustment screws. Jim (24868) |
| More 3-jaw
chuck questions |
| I have
confirmed the accuracy problem with lies with the fit of the
backplate on the lathe spindle -- just as most suspected. James Early's post a while back noted that .004 was about the best one
could expect in fitting a factory machined backplate to the spindle
registry. In my case, the gap is .006, and the fit on the threads is
not particularly tight -- the face plate can be rattled around quite
a bit just before it seats against the spindle shoulder. It has been
suggested that the best solution is to get a blank backplate casting
and machine a backplate to fit. I understand that one. Do you think
it possible to try to salvage the factory faceplate by boring it
out, pressing in a bushing and then machining a proper fit?
Alternatively, how about drilling three or four holes around the
base of the faceplate and use screws that would bear on the lathe
spindle register (not the chuck register) to center the backplate?
(or is this just a great way to damage the spindle register?) Dave
(24890) |
| IMHO I
would not put screws in to bear against the spindle I think (even
though it's hardened) it's asking for trouble. If the backplate is
the problem, would they swap it for an un-machined plate? Seems they
have some responsibility here. George(24891) |
| Dave, 3 jaw
chucks are notoriously poor TIR. For accuracy use the independent
adjustable jaw chuck (4 jaw). The scrolls on the 3 jaws are never
made to great accuracy so the position and amount of runout will
change as you hold different size pieces. This is something you have
to live with. 003 inch TIR is commonly spaced for Bison chucks, not
003mm. The fit of a backplate is flat against the shoulder on the
spindle, this should be square for a perpendicular fit. With Vee
threads the plate will self center as it is tightened against the
shoulder, loose threads are OK. You may be able to improve the fit
by repositioning the chuck on the backplate. For convenience use the 3
jaw chuck, as long as all operations are done at once you are fine,
for secondary operations you need a 4 jaw or collets. It seems to me
that you may be getting overly concerned over this but then again I
can be an opinionated SOB. JP (24892) |
| I
have read articles on "fixing" a backing plate just as you propose.
I think it was Rudy Kouboupt who wrote it. All he did was bore out
the register section and press in a sleeve. Then bored to fit. He
didn't redo the threaded section. It sounded like it would work
well. This of course presupposes that the spigot section of the
backing plate is concentric with the register. If not, I don't think
it will fix the problem completely. Webb (24894) |
| Sounds like
damage to the expensive spindle will occur. Nick (24895) |
| A better plan
may be to remove the back plate from the chuck mount the back plate
to the spindle that the chuck will be used on. Then face of the back
plate and remachine the back plate to fit the chuck again. This is
possible only if the back plate is thick enough. I found this
excellent article on machining back plates on a UK web site.
Nick (24896) |
| Dave Did you
study well the Duplex article on chucks in the link I included. That
article deals directly with the problem you have and how to do a
reasonable correction. The new backplate you thread and fit to your
spindle is of course the best option, but the Fix shown by Duplex
will at least make your current backplate usable until you can make
one.
http://groups.yahoo.com/group/mwhints4/files/LatheChucks/
JWE (24897) |
| Dave, It's
probably better to cut your losses and machine a new backplate from
scratch. When you've sorted out fitting the old backplate to the
spindle nose then you still have to turn the register below size and
play around with centering screws. The best bit of advice in all this
was to make a dummy spindle nose first and use that to check the
threads in the new backplate. Frank (24902) |
| I
would machine the backs of the screw heads they probably have a
slight radius where the head meets the threads and it is causing the
plate back into its original position. fred
(24909) |
| Or the hole
was not finished with a counterbore to give it a flat bottom. JWE (24918) |
| Jim The
method used in the Duplex articles was how I was taught in shop back
in the mid 50s and for me it still works. I would rewrite it myself
but Ian is a far better writer than I will ever be. I have repaired
two backplates this way over the years. The first was a Polish unit
that was threaded and mounted when I got it in 1978. I took the
chuck off the back plate and trued the register face surface that
had a couple of dings that knocked the chuck out of true when pulled
down. The register bore was within tolerance so I did not change it.
I then recut the face and chuck register and still use that chuck
today with about .002 average runout. The other one I had to fix was
the second back plate for the 9x20 I bought last year. The first one
was so bad a fit to the threads I took it back to the store and
exchanged it for a better one. I also trued it up and it holds a
fairly consistent .003 runout because its threads and register bore
are a bit loose. Also some times you will need to use a counterbore
bit or end mill to flatten out the holes the screws go in if you try
the adjustable bit with a loose chuck register. JWE (24919) |
| James What I
don't understand is that the chuck backplate will recenter to within
about .0005 even though the backplate register is more than .020
larger than the spindle register. ??? I can bore and sleeve the
female register to correct tolerance, but I don't think that's going
to help. The chuck jaws fit very snug in their slots and the scroll
is also a very good fit. The fit of chuck to backplate is also good.
The chuck shows lineup marks on the O.D. where someone else has
disassembled it besides me. They may have been looking for the same
problem. I guess all this rambling is just me grasping at straws. If
anyone has an idea to correct the runout ( .005 on work chucked), I
would appreciate it. Jim (24924) |
| 3-Jaw Vs.
6-Jaw |
| I was just about to
purchase a 3 jaw chuck when I thought about stuff like tubing...
granted I don't work with tubing that often. But I thought if the
six jaw chuck will do everything that a three jaw will and more,
then I would just go ahead and get the 6-Jaw. So I guess my question
is: Can you do anything with a 3-Jaw chuck that you can't with a
6-Jaw? (24980) |
| I've found my
6-jaw doesn't hold parts as well as the 3-jaw, such as when die
threading larger sizes. I try to not over tighten any chuck, so
maybe my problem is due to this. Still, I use the 6-jaw almost
exclusively and only switch to the 3-jaw when I find the 6-jaw not
holding well enough. Rick (24981) |
| Jerry, I
think a four jaw independent chuck is more versatile than any 3 or 6
jaw chuck. Someone else stated not to long ago (not sure which
group) that a six jaw was only good for tubing and other thin
material. You can work on very thin stuff by making a thicker sleeve
of say steel and put a saw cut on one side. With a four jaw you can
get it centered very precisely, and the sleeve would prevent
distortion. For thin stuff if you go the six jaw route you might
want to get a chuck with the set true feature. Jim (24982) |
| I
tried to convince myself that I didn't need a three jaw chuck,
because you can (with lots of time) adjust out nearly all runout. I
am just an impatient person when it comes to centering work that I
am not just trying to dust of a couple of a thousandths of an inch.
I see the 4 jaw as being used for two things. Odd shaped parts and
extreme accuracy that you can't fit into a collet. But then again, I
don't even have a year of experience under my belt.. so what the
heck do I know. I think I just need more experience. It takes me
forever to get a part centered to within .035 runout. It drives me
crazy. Please. I would love to hear more of the practical wisdom
that comes from experience. With this trade/hobby book smarts don't
mean a whole lot. Ben (24986) |
| Collet.
They're also pretty useful if you want to turn something off-centre
(eccentric) on purpose. Nick
(24991) |
| Love my 6
jaw, with the adjust through back you can get real accurate work.
(24994) |
| I don't know
how the info on a 6-jaw got construed as only good for tubing.
Actually, the 6-jaw will distort tubing as will a 3-jaw. The 6-jaw
might distort the tubing a bit less though. The 6-jaw does seem to
hold round stock a bit more securely. The main disadvantage to a
6-jaw is cost ($$). The only part I could think of that a 6 jaw
wouldn't hold and a 3-jaw would, would be a triangle. I can't
remember if I ever turned a triangle piece. The 4-jaw is more
versatile, but take a bit more time to dial in. Some 6-jaws and
3-jaws can be adjusted to an extent. Buck chucks have this feature
as do others. Tom
(24996) |
