| Stuck chuck! (Apr 8,
2001) |
Stuck Chuck! Help! (Feb
8, 2003) |
| Stubborn chucks
(Jun 3, 2001) |
Stuck chuck (Jan 14,
2004) |
| Stuck chuck....help! (Feb
4, 2002) |
Stuck Jacobs Chuck (Oct
27, 2004) |
| Stuck Jacobs Chuck (Apr
26, 2002) |
Stuck Chuck (Oct 30,
2004) |
| |
| Stuck chuck! |
| I changed chucks
today from 3 jaw to 4 jaw to do some 'precision' work. now I can't
get the 4 jaw off! tips? tricks? My usual procedure: I take a piece
of 2x4 put it on the back side of the chuck, blocking the jaws from
turning. put it into back gear, bump the reverse switch.
conservation of momentum of chuck vs. spindle drivetrain. Usually
comes off on first try, maybe second. I've done it like 6-7 times,
increased belt tension, added penetrating oil. no luck. I don't want
to try a bigger hammer unless I have to. any ideas? dennis (500) |
| Some folks use the backgear and the bull gear pin at the same time to more or less lock
the spindle, then twist the chuck off with their hands, or when more
leverage is needed a chunk of wood between the chuck jaws. This is
very risky on a machine like an Atlas with brittle cast gears. On a
Southbend it is somewhat safer, but still risky. (Okay, I admit I do
it all the time, but usually only turning the chuck by hand.) When
you do manage to get the chuck off, make yourself a thread cleaner
out of stiff wire (imagine the letter U with the very points bent
outwards and filed to 60-degree points) and use it to chase any
chips out of the threads before mounting. Chris (501) |
| Stubborn chucks |
| I am trying to
figure out how to remove the chuck from my 9 inch SB. Everything I
have read indicates that this should be a fairly easy job but I
don't think that they took my lathe into consideration, my guess is
that this three jaw hasn't been removed for about twenty years. I
had considered engaging the backgears and using a large oil filter
wrench (with a piece of leather wrapped around the chuck). Would
this work? or would I screw something up? Would it be a good Idea to
get a little penetrating oil on the spindle threads. Matt (785) |
| Matt, Maybe obvious and you may have
tried it, but with back gear engaged use the chuck key to give it a
gentle by firm jerk, this generally breaks it. Kerosene works
wonders as do the regular liquid wrench, just keep squirting for a
wk and then try the chuck key. I have also run across a left handed
chuck backing plate, so I know there is one spindle in the world
that has one, but would not think this to be the case on your 9" SB.
big tom (787) |
| I am not sure how
good this idea would be for the chuck or the chuck jaws but you
could do it like a three jaw chuck is removed from a hand drill.
Place the largest Allen wrench that will fit into the jaws and
tighten the jaws down. Then give the Allen a rap with a hammer it
the proper direction. Acts sorta like an impact wrench. Gerald
(788) |
| I'm not sure I would want to put a shock on cast iron,
especially the small gear teeth that make up the back gears. They'll
apparently take quite a bit of steady force, but not impact. The
hand drills I've taken apart have used steel gears and can survive
an impact wrench approach a bit better - YMMV. I use a 4 foot steel
bar on my 2.25" thread lathe chucks to get them off - the chuck key
by itself would never make it (or I'm not lifting weights enough). I
simply engage the back gears, clamp the end of the bar in the jaws,
and pull. Nice and steady, no shock needed. Installation doesn't
require a bar, by the way - just spin it on until it "thunks". Mike
(789) |
| Matt, Tom, all,
From the SB book, "How to run a lathe": "To start a chuck so it can
be removed from the lathe spindle, engage the back gears, place a
wood block between the chuck jaw and the back ways of the bed, as
shown in Fig. 156 [Fig. 156 shows a wood block resting vertically on
the back ways and is just long enough to sit under one of the jaws
when horizontal], and turn the cone pulley by hand. After starting
the chuck, place a board across the bed ways to protect them from
damage in case the chuck is dropped off the spindle. This procedure
also applies to face plates." I guess the x10 leverage advantage of
the back gears should help, and no shock impact to the teeth. Other
manufacturers and texts say you can engage the back gears but not
pull out the bull gear pin effectively locking the spindle, and then
using a crescent wrench on one of the jaws. The SB recommended way
is the best way to avoid damage to back gear teeth. If you really
have a bad situation after soaking the nose threads in Liquid
Wrench, how about a strap wrench on the cone pulley and a piece of
wood (as described by SB) on the chuck? Try it first w/o back gear
so you can save them from the stress. According to SB, make sure
nose and chuck threads an mating surfaces are clean and lubricated
before assembly. I've got an article that describes the process of
refitting a chuck to a spindle by marking and scraping. The result
is an accurate, easy-on, easy-off chuck. I've got to do that to my
chucks and face plates. When your chucks and face plates are not in
use, store them in such a way that the nose thread registering
surface is protected -- chuck face down, in a wooden box or hanging
on the wall on a wooden dowel. Mine have been mistreated over the
past 60 years and could use a little TLC. Paul R.
(791) |
| The article I
referred to previously is "Stuck Chucks, One-more-time, Didactic
#17" by Henry J. Kratt, in HSM's "Projects Seven" page 33. Anybody
else have it? It's a single page, but I have no flatbed scanner.
I'll see if I can fax it to myself in order to scan it in, but if I
can't, or if the quality is poor, maybe I could send it to someone
and they could scan it and return a PDF file. Paul R. (792) |
| I *love* it! Also
tried it, and tried it, and tried it. Anyone else attempt it this
way and achieve success with the small lathes? No offense intended,
but it never worked worth an ounce of bovine excreta for me. On
a 9" or 10" SB, the pulleys are too small to get much of a handle on
- the larger models are a bit better in this regard. This procedure
reminds me of the automobile shop manuals where they show a pristine
engine and a spotlessly white clad mechanic using tool J-2775 to
"easily" remove the whatsis. After a few years neither the "real"
engine nor the mechanic seem to look like that in the photograph,
and the whatsis has corrosion-welded itself onto the engine in such
a manner that you have to use dynamite to get it out. Unless you
have lapped and scraped your chucks to fit perfectly, I'd say you
were lucky if they came off as easily as SB says here. In the real
world there is almost always a difference between theory and
practice. Please note that I have no problem at all with SB's
process - if it only would work! It seems to me that the guiding
principle here should be one of understanding the cast iron back
gear limitations and using whatever techniques are suitable for the
material. Locking the spindle with the back gear, as I suggested,
will be effective up to a fair amount of STEADY torque without
breaking anything. There's no practical difference in using the
locked spindle versus the "hand-held cone pulley" approach as far as
I can see - UNLESS you're trying to use *impact* to loosen the
chuck. A locked spindle doesn't have any shock absorbing ability
like the hand-held approach does. Above that admittedly subjective
torque level, it's necessary to block the spindle some other
way...may even require removal and gripping the entire assembly in a
vise, if it's the first time in 30 years. Mike (794) |
| Since quill and
bull gears are expensive, I tend to be cautious about the gears. If
I break a tooth on the bull or quill gear, I'm hurting. I'll go as
far as locking the spindle and seeing if I can remove the chuck with
my hands. If I had a real stubborn chuck, I'd first get/make one of
those strap wrenches for the largest step on the cone pulley, have
the lathe in normal, NOT back-gear, place a wood block under a jaw
and pull with the strap wrench. With the gear in normal, the cone
pulley is coupled to the spindle via the bull gear and a steel pin.
That should survive just about anything. I'd even use a cheater on
the strap wrench. If it breaks I'm only out a cheap strap wrench.
You could also try the strap wrench and a crescent wrench on a chuck
jaw and while under tension, tap the crescent wrench with a hammer
to see if that starts it turning. The other way to do it is to
design a project that can only be turned in reverse. Then as soon as
you start cutting, the chuck will spin off and ding your ways ;-)
Good luck, but try everything else before stressing the gear teeth.
Paul R. (795) |
| Paul, I have
been using the locked in back gear method to take the chuck off
since 1955, have I been doing it wrong all these years? JWE (796) |
| JWE, I've been
using the locked spindle/hand removal method but I don't think I'd
hammer on a chuck locked in back-gear -- not unless I already
exhausted every other means of getting it off, and then only if I
had a source lined up for spare gears. All I'm saying is try the
other stuff first if you get to the point when you need to apply
that much force, then go ahead and try locked spindle (but no
impact). If you need to pound on it, hold it some other way. There
was an article about a mill/drill quill repair for an owner that was
trying to pound out a 3MT w/o locking the quill. It busted every
tooth on the quill. Paul R.
(797) |
| Paul, now you
know why I prefer a R8 spindle on a mill/drill not a MT. JWE (798) |
| Just had the
situation myself on a light 10 I purchased from a guy who had bought
it at government auction. Realizing that the back gears were
breakable, I used carpenter's wooden wedges from Home Depot and
inserted them against the spindle inside the flip cover to keep it
from moving, yet safe from breakage. My problem was a frozen
faceplate backing and I had to insert a bolt in one of the backing
holes and then strike the bolt with a hammer and large punch. It
acted as an impact gun but only after soaking the faceplate with
WD-40 overnight.
(799) |
| I suppose in a
really hopeless case one might be able to machine a backplate off
the spindle... I'm not sure what it would be like when one got down
to the major diameter of the threads though - could be tricky to do
the job without damaging the spindle thread. I know this is the
South Bend list, but anyone have experience removing the Sherline
3-jaw chuck? I was given an old lathe with a 3-jaw rather stubbornly
affixed to the headstock. Chris (800) |
| In the end it is up
to you what method will work best but I for one cannot recommend
using any kind of impacting force ( a hammer or an impact ) on the
choke or if you prying against the chuck jaws you can pretty much
throw the chuck in the garbage. .and as far as turning the choke
backplate off I guess it could be done but it would be very
difficult to keep from damaging the threads. You might try removing
the Chuck from the backplate and attaching a long bar to it for
leverage a slow and steady pull should do it. Placing a piece wood
under the Chuck is a good idea but I prefer a 3/4 wooden bowel
through the Chuck that extends into the shaft about 8 in, I leave
about 4 in. extended beyond the Chuck for a handle it gives me and
easy handle the hold and will not allow the choked to fall. It
sounds like you have a lot of good advice. The people in this group
has a lot of experience in should know what they're talking about.
Even though I do not agree with using an impact. That would be a
last resort and not one I would care to use. I would consider buying
a new shaft and replacing it first. Bill (802) |
| There have been
many responses to this question, and I will add one more, from LOTS
of experience. First, I have never used impact force of any kind,
and would NOT recommend it. Cast iron gears WILL break under impact,
and such gears are not generally inexpensive. Second, please do not
use the chuck key to remove a stuck chuck. You will break the key
(OK, not too expensive), or damage the scroll pinion (tends to be
VERY expensive), or damage the chuck body around the pinion (we
won't even talk about that kind of expense). You probably noticed my
last name, and yes, my experiences are with Logan Lathes. No, I have
never owned a South Bend, but we should all be able to agree these
two brands are more similar than they are different. Now for what
does work. Place a length of steel, brass, or aluminum bar stock
(heavy wall square tubing works wonderfully) CROSS-WISE against the
chuck face. On a 6 inch chuck, a piece of 1 inch round or square
will work quite well. The length of stock may vary depending on how
tight the chuck is. I keep a piece of scrap near each of our Lathes
about 2-1/2 to 3 feet long. Close the jaws so that they will hold
the bar solidly. You will have 2 jaws on one side of the bar, and
one on the other. Rotate the chuck and bar so that the bar is at a
comfortable pulling angle. You want to be pulling straight down, so
gravity and your own weight will assist. Now lock the Back Gears.
Engage the Back Gears, but do not withdraw the Bull Gear Pin. Next,
pull down on your bar. DON'T whack it with a hammer. Pull down
steady. Only on rare occasions has this failed to release a chuck
for me. Some of you have met me, and know that when I put my full
weight on the bar, there will be a LOT of torque on that chuck. On
the rare occasion when this has not worked, the only additional
thing I have done is to gently "bounce" my weight on the bar, while
hanging completely supported by the bar. This does not impact the
gears, I don't bounce that hard to completely release pressure. For
reference, I have "bounced" on the end of a five foot bar to remove
an 8-1/2" Buck Adjus-Tru chuck from a 14" Logan Chucker. I was
putting enough load on to almost tip the entire lathe over (~2000 lb
lathe), but did no damage to the lathe, spindle, chuck or gears.
This particular lathe has a 2-3/16 x 10 (Hardinge) threaded spindle,
which can get VERY tight when turning 8-10" diameter cast iron parts
in a production environment. What I recommend to my customers, if
all this does not work, is to disassemble the chuck as much as
possible, and turn the remaining back plate off the spindle.
Drastic, but if the only loss is a back plate, it is much less
costly than replacing the Back/Bull Gears. Hope this information
helps, and that I have not rambled on long enough to completely bore
you all. Scott Logan(803) |
| Scott, perhaps you could shed some light on something I've
always wondered: why were none of these class of lathes built with a
real spindle locking mechanism? Was it just assumed that one would
use the back gears carefully as you describe? Or was it a cost/space
issue, which would explain why 10EE's have a lock even though they
have usually have camlock spindles, and SB's and Logan's which are
usually threaded do not? Chris (804) |
| First, everyone
should understand that when the Logan Lathes were being built, and
especially when they were being designed, I was not involved at all.
Logan Lathes began production in 1941, and my parents began
"production" in 1960. My estimate is that, as you surmised, it was
a cost/space issue. The other consideration is the possibility of
someone stopping the lathe with this lock while it was running. If
it were a brake mechanism, it could easily allow the chuck to
unscrew. Scott Logan (805) |
| The lock on a 10EE
is for loosening a hand wheel collet closer among other things like
indexing the head stock on multiple start threads. The 10EE is in
direct drive much of the time and there are no gears to hold it. It
isn't really a good comparison. A lock on a threaded spindle could
be a real disaster. One of the ways of breaking a threaded spindle
chuck loose is to get an L shaped bar and chuck up the short end
then get it moving by hand in the direction of tightening and then
give it a sharp blow with the palm of you hand on the direction to
loosen the chuck. This will usually break even the most stubborn
chuck loose after a couple of tries. Yasmiin (806) |
| Matt did you
get the chuck off yet? We are interested in which method you chose
from these fine posts, please let us know. Joe
(812) |
| With any luck I'll
get a chance tomorrow to work on it, When I find out anything I'll
let every body know. Thanks for all the help, I really appreciate
it. Isn't the internet great. Matt
(813) |
| I got the chuck
removed from my lathe today. I used the wooden block, engaged the
back gears, and slowly turned the gears and amazingly it came off.
My next question is how do I remove the carriage assembly?
Matt (835) |
| Good going, Matt, I
recall I removed the carriage after removing the lead screw
tailstock bracket (and tail stock, of course). Don't recall if I
first removed the apron, though. You might have to clear the end of
the rack. Then you should be able to slide off the tail end of the
lathe ways. BTW, the apron comes off with two big screws.
Paul R. (836) |
| Stuck
chuck....help! |
| I am in the process
of stripping down the 14x60 South Bend lathe that I bought last
month. I have not had any problems with it until I tried to remove
the three jaw chuck from the spindle. It won't budge and I've tried
everything I can think of. It is a chuck that is bolted to a back
plate that is then screwed on the spindle nose. I can get the chuck
body off by removing the three hex screws that hold it to the back
plate, but the back plate it firmly stuck. I tried using a 2 foot
length of pipe chucked sideways in the chuck as a lever arm then I
locked the spindle and tried to unscrew the chuck from the spindle
nose, it will not move at all in either direction. Does anyone have
and suggestions or know what I'm doing wrong? Will heating the chuck
with a propane torch harm the lathe? Which direction does the
spindle threads go to loosen, right hand or left hand? Mike
(3075) |
| Mike, Congrats
on the lathe acquisition. I'd love to have a bigger lathe (and the
space for one). Personally, I cringe at the idea of heating parts of
the lathe, and if the chuck is that tight, I would think that
everything would expand at about the same rate. "How To Run A Lathe"
says to put the lathe in back-gear, place a board between the rear
(horizontal) jaw and ways, and turn the cone pulley (in reverse) by
hand. I wonder if you could engage the motor at its lowest speed? A
flat belt would probably slip before the stuck chuck released,
though. I wonder if the chuck has been on so long that it is rusted
on tight. Can you get at the front of the spindle and have you
applied some liquid wrench to soak and then some very thin oil? I'm
not sure how much stress the back-gears can take if you lock them
and use a pry bar on the chuck. Stumped, Paul R. (3076) |
| I cringe about the
motor at its lowest speed option. I won't go into the details of
why. Lets just say white painted lathes can jump. If you suspect the
threads are rusted on, I would spray with RustBuster. Go to your
auto parts store. It should be in a white can with black print and a
yellow label. I'm not sure if its actually called RustBuster, but
something to that effect. I would heat up the backplate. Not a lot,
and use a propane torch. You shouldn't be able to get it too hot
with a propane torch. You might let it cool, then apply the oil
again the reheat. I had some header bolts that I couldn't get out. I
bent some punches that I used as a wrench with a drilled through
hole. Didn't work. I heated up the bolts with a mini propane torch
and they came out. Not real smoothly, but not a whole lot of effort.
I'd see what other have to say first though. I think the worst case
is to cut longitudinal grooves with a Dremel on the plate, but you
might risk cutting into the spindle threads and the back plate would
be scrap. Tom (3079) |
| Mike, The spindle
thread is a standard right hand screw direction (it tends to tighten
on the spindle when the lathe turns in the forward direction. I
believe the thread size for the 14 1/2" lathes is 2.25"- 6tpi. I
don't know what the melting temperature of babbit metal is, but I
would guess that damaging the bearings is the biggest danger of
heating the chuck plate. After you apply your penetrating fluid and/or
heat, try tapping around the chuck plate (not too hard) with a
hammer, while applying a constant torque. If you give up on a clean
removal, it should be easy to just machine the back plate right off
of the spindle. The back plate is made of soft steel or cast iron.
You can progressively turn it down to a nub, to just over the
diameter of the spindle. Eventually, all that will remain will be
the original internal threads of the plate. You should be able to
uncoil these right off of the spindle. Jon
(3080) |
| Put the largest
round piece of scrap you have in the chuck. Put a piece of wood
between the ways and the chuck for when it (hopefully) falls off.
Put the lathe in back gears at the lowest speed available. Install a
non-favorite toolbit upside-down in the lathe, turn spindle on in
reverse and proceed to take a nice heavy cut. (Turning, not facing) I
have never known this to fail. Just be ready to catch the chuck.
Good luck. P.S. The broken back gear teeth we have been hearing
about come from pounding on the chuck with the back gears engaged
and the spindle pin in. Don't do it. PeterS
(3081) |
| A torch and
that penetrating oil isn't a good combination. Make fire. I know the
oil he is talking about and it will break loose about anything given
time. As far as breaking it loose I would suggest a lever with a
right angle that you can chuck up and have the long end at right
angles to the center line. Then put the lathe in the lowest gear
there is and push the lever back till the spindle is moving and then
try to snap it hard the other direction. This will give a good jolt
to the threads without messing up the chuck or the spindle. Do this
a number of times if it doesn't come loose then spray on some more
of the oil and wait a day and try again. If a week of this doesn't
do it then harsher measures are required. Remove the chuck if you
want to save it and drill and tap an extra hole across from one of
the chuck mounting holes. Make a bar to match and see if you can
break it loose with a dead blow hammer keeping the spindle in low
gear. Don't lock the spindle as you are going to start breaking
parts. If that doesn't work then you are going to have to cut off
the back plate which is another venture which I hope you don't have
to get into. I know the frustration -- I have a small lathe with a
collet frozen into the spindle and the closer is rusted to the
collet. I am still spraying oil on that situation and trying to
figure out what to do. Its in an expensive instrument lathe and
there is nothing much to even get a hold of. Yasmiin (3082) |
| I believe the
penetrating oil I am referring to is called PB Rust Buster or Rust
Blaster. Yes, I'd try letting the oil soak a few days first. It
usually goes without saying to have a fire extinguisher on hand. I
was unaware that there are babbit bearings in the head stock. I
though they were bronze. I'm also not talking a lot of heat, maybe a
bit above warm to the touch. Just trying to get the plate to expand
enough to break the rust's hold. Rust almost acts like a glue in a
sense. Tom
(3086) |
| I had a similar
problem on an old Flather lathe ( just like a SB 14") I was able to
unscrew the chuck and reuse the backplate. After trying most of the
methods suggested, I decided to part off the back plate. First
removed the chuck. Fashioned a tool holder to get around the plate.
Ground a parting tool about .060" wide and positioned it about .010
from the diameter the plate buts up to. Carefully parted in to
within .030" of register OD.( measured the register OD from another
chuck that fit this lathe or in the case of a SB could have gotten
on the web, etc.). When I got close to cut in position, I tried and
succeeded in unscrewing the back plate. Since I only took off about
.070" I was able to chuck mount the back plate, indicate and
increase the register depth. Put the parts back together and it
worked fine with no cost except time. Walt (3088) |
| The bearings in the
head stock of my lathe are bronze not babbit, so a little heat
should be ok as long as I apply it to the adapter plate and not the
spindle. I just came back from the auto store. The closest thing
they had to what I think you guys are talking about is a can of
something called "PB Powerful Penetrating Catalyst" It looks like
the right stuff, expensive at $3.99 a can, but I hope the right
stuff. I will spray some on both sides of the adapter plate where it
threads onto the spindle when I get home tonight. Mike
(3092) |
| For corroded parts,
use General Motors Heat Riser Penetrant from a GM dealer - about
$7.00 a can. It is excellent! To remove a threaded chuck, why not
chuck-up a large bolt? Use a 1/2" or 3/4" impact wrench to back it
off. Ed (3096) |
| I didn't think of
using an impact wrench and as luck would have it, my wife bought me
an air compressor with some air tools for Christmas, so I could try
it if I want. The impact wrench has a reverse rating of 600 ft*lbs
and a forward rating of 400 ft*lbs I would think that would be
enough to free up the chuck. My only concern would be the welfare of
the lathe, I don't want to damage anything and I'm not sure if an
impact wrench would be safe to use or not. In the mean time I
removed the chuck from the back plate and sprayed that PB Rust
Buster on the front and back of the plate where it screws into the
spindle. Mike (3100) |
| I *KNOW* I'm going
to regret this, but please do NOT use an impact wrench on your
Lathe. The damage this is likely to cause will cost you FAR more
than the chuck back would cost to replace, if you have to go so far
as to turning it off. Scott Logan(3102) |
| This creates a situation where the thing your trying to
remove has more mass than the thing your trying to remove it
from. That's not how impact tools work, they rely on the larger mass of
the thing the bolt is in, to hold it still. Lugnuts being the best
example. Locking the headstock and putting one of those things on the
spindle is a sure way to shatter one of the back gears I'm not sure
whether your dealing with a corrosion problem or if chips have
gotten on that spindle, and jammed the fit, but sharp blows should be
avoided. If your convinced that its a corrosion problem, it might
help to remove the spindle from the headstock and immerse the nose
end of it in kerosene in a 5 gallon bucket. Just put it in there and
forget about it for a while. I freed up a frozen headstock bearing
(Tool steel) of a small lathe that way just last year. Many years ago
I found a monkey wrench in the mud, completely rusted, I left it
immersed for months, actually did forget it. When I discovered it
lurking there, it was operable. RC (3104) |
| You might try dry
ice on the spindle and headstock after you have done the propane
torch trick on the faceplate. I got some a few years ago at a Baskin
Robbins Ice Cream shop. It works great for removing bubble gum from
automotive carpets. I'm not sure how it would work on hair. Glen
(3105) |
| I think that if you
rotated the gears away from the spindle so that there was nothing
engaging the gear on the end of the spindle and tightened the chuck
down good and tight on a big bolt so that the head stuck out and
then you ran the impact at a reduced air pressure you could safely
run the impact to get the chuck unstuck. Gerald
(3106) |
| The mass is wrong
for an impact wrench. The force is absorbed by the mass of the
chuck. Running with reduced pressure might give enough jarring to
the spindle threads to help break the bond, if in fact rust rather
than stretched threads is the problem. Don't overlook strap
wrenches, one on the cone pulley and one on the chuck, have been
used a few times around here to get a stuck chuck undone on lathes
being rebuilt - once on my SB13, once on my neighbors SB15. On the
15, we ended up removing the 13 inch 4 jaw from the backing plate
and bolted a 6 foot length of steel bar to the backing plate. My
neighbor had soaked the joint with Rust Buster twice a day for a
week. He held the cone pulley with a large strap wrench, I stood on
the end of the 6 foot steel bar (I go just shy of 270 pounds), and
my son tapped (not beat, just tapped) the backing plate all around
with a 3 pound hammer. I didn't jump on the bar, we didn't beat on
the bar. A minute later it was off with no harm. Patience and
thought rather than brute force undo things better. Brute force is
what got the thing stuck in the first place. If we had beaten the
bar, the force would be transferred through to the pin that locks the
spindle to the cone pulley, not a good thing. Same approach as when
tearing down a suspension in a car if you've done that. The force
applied by the puller is heavy but constant, the tapping with the
hammer gets it to jump loose. Once the chuck is off, check the back
surface of the chuck backing plate. A pip or burr on this surface
(or on the spindle face) will cock the chuck, resulting in jamming.
I put a smear of Prussian blue on the mating face of the spindle and
turn the chuck on once any visible defects are removed. It is not
uncommon to find only a single small point of contact. Scrape or
stone this area, and offer up for fit. Repeat until you have 70
percent or more contact area and stuck chucks become an ugly memory.
About the only way to make a chuck jam once properly mated is to
switch from reverse to forward abruptly with a slightly loose chuck,
or perhaps a horrendous tool crash at high speed. Clean your spindle
threads and chuck threads before mounting, oil lightly, and life is
good. Stan (3117) |
| What he said. I'd
rather zorch a $40 backplate than a $400 spindle. (3118) |
| I think the key to
not having a stuck chuck is like Stan said they need to be fitted,
that's what the file that I uploaded (Stuck Chucks) is for, fitting
your chuck to your spindle. Randy (3119) |
| Lathe spindle threads are a normal right hand
thread (Other wise working forces would tend to loosen them.) I
would not try a torch on the chuck back plate though, I have had
stuck parts on various projects and used penetrating oils applied
daily for a week or so. One suggestion I have seen was to stuff ice
or dry ice into the spindle hole and warm the plate with a light
bulb, but not much hotter or if you have a friend that is into model
airplanes you may be able to borrow one the low temp heat guns used
to shrink plastic film on models. John (3120) |
| I plan on fitting
the chuck after I get it off. (3121) |
| I am grateful for
all the suggestions. This is what I'm doing: I have been spraying PB
rust buster on the front (and back) of the back plate twice a day
and I have bolted a four foot 2x4 to it (the back plate) using two
of the three holes for the chuck's hex screws. I've hung a five
pound weight on the far end of the 2x4 and have locked the spindle
using the back gears. I believe that with the constant torque on the
back plate added together with the rust bust and some light tapping
once and a while, the chuck will eventually come loose. Notice that
I'm not using any heat nor any sort of *impacting* force to loosen
the chuck. This whole lathe refurbish is a very exciting project for
me. I'll have to wait until the weather gets warmer in order to
clean and repaint the lathe bed, drip tray, motor enclosure and the
stands, but I'm cleaning and repainting the rest of the lathe 's
parts inside my house. I am currently doing the tail stock, cross
slide, and compound slide. I will do the saddle next, but I'm having
trouble getting the four huge slotted screws that hold the saddle to
the cross-slide-ways loose. The screws are very tight and I have not
been successful finding a big enough screw driver that allow me
enough torque to remove them. The biggest screw driver I've found
has a 3/32nd's inch thick blade and is 3/8th inches wide and it's
not working. The slots on the screws measure 1/8th by about 5/8th's,
so the screw driver doesn't fit snugly and I don't want to mess up
the screw slots but applying too much torque. I don't know what to
do except make something that will fit the slots on the screws more
closely and then using more torque on the tool to get them
loose. Any other
suggestions? Mike (3123) |
| Not a glue, even
worse! When iron combines with oxygen it makes rust of course, but
rust is larger than the original iron. So rusted parts are expanded
into each other, which is why you need some kind of penetrating oil
that tends to dissolve the rust.
(3124) |
| Mike, go to sears or
stop any tool truck like snap-on or Cornwall and get what I think is
called a drag link socket. They will fit a 3/8 ratchet and they used
to carry about 10 different sizes of them. JWE (3125) |
| Couple of options:
Grind a piece of one inch drill rod to make a nicely fitting blade,
cross drill for a tommy bar. Not a real fun project, as you have a
LOT of grinding to do. Optionally, hacksaw out most of the waste and
grind to final size. A much better approach provided you have a good
hacksaw frame and some decent blades. Make the above, but replace
grinding with milling, should you have or can get access to a mill.
This is what I did. Milled a hex on the opposite end, and used a
socket on a ratchet to turn it. Piece of cake with a spindex and a 1
inch 5C collet. If you have an OA torch or a forge, forge a tool
from drill rod. 1/2 rod hammered out to a blade, then bent 90
degrees will work. Press down with a backer when using a tool like
this. After final quench draw to a medium straw. Drill rod needs a
bit more heat than mild steel to forge, just don't burn the carbon
out of the tip. *** EASIEST OPTION :-) *** Get a drag link socket.
This is a big screwdriver blade for a square drive, all one piece.
Sears had them last time I looked, you can also find them at tractor
supply and heavy equipment dealers, although much of the stuff at
the local tractor supply place was low quality import by the time
they went belly up (cause and effect analysis anyone?) You may have
to do some grinding for width and thickness, but it beats heck out
of grinding one from solid. Not the greatest approach, but in
desperation when far from mill or a tool supplier, I've hacksawed
and filed steel plate to fit into large screw heads, grabbed on with
vice grips, and pressed down hard with a piece of wood to prevent
slipping while turning. Once the screws break loose, you'll be able
to turn them out with a large screwdriver. They turn freely after
the first 1/4 turn or so, so an approach that is really awkward is
only needed while breaking free. Stan (3130) |
| I didn't think of using an impact wrench I would not think
of it either. And I don't think it would be a good idea until all
other means have been tried such as constant weight plus penetrating
oils. Or ice in spindle and light bulb heating of stuck part.
(3139) |
| Can not you just
take the right hand bearing for the lead screw off and crank the
saddle off the end? Of course remove the tail stock first. John (3149) |
| Stuck Jacobs
Chuck |
| I have a Jacobs 6A
chuck on a MT to Jacobs adapter. I cannot remove it by the usual
means. Since this has crossed everyone's plate at one time or
another I am hoping that someone will have an idea. Fred (4076) |
| Fred: I don't
know what you tried in the "usual means" category so I will assume
you just tried the wedges. Penetrating oil often helps here. (e.g.
Kroil) You can try gently heating the chuck body. Don't overdo it!
Drilling a hole at the back of the chuck and using a punch to drive
out the arbor usually works, and doesn't affect the functionality of
the chuck. Dave (4077) |
| You might consider
drilling a 1/4" hole through the front; then knocking out the arbor
with a punch while properly supporting the back-side of the chuck.
The arbor face usually does not bottom out in it's socket. (4078) |
| Fred, I went thru
this not too long ago. Basically you've got 2 options. either check
with the online suppliers or a local industrial supply and get a set
of wedges that are specifically designed to force the chuck off of
the arbor. These will only work however if the arbor has a shoulder
on it for the wedge to seat against. The only other option is to
drill a hole thru the soft bottom of the chuck and either use a shop
press, arbor press or a good hammer and force it out with a drift. I
tried all of the above including a 10 ton arbor press on the very
same 6A chuck and finally resorted to a 1/2" drift a 5lb. maul. Let
us know how you make out. Dave (4080) |
| I had a similar
problem with a chuck on an MT2 shank. I turned the shank down to
1/2-inch, and cut threads on the shank. Then I placed a cylindrical
tube around the shank, and a plate with a 1/2-inch hole over the
shank. I cranked down on a nut, which pulled the shank out. This, of
course, destroys the shank. (4081) |
| Dave's, FMP, Jon,
Thanks all for the tips. I already tried the drift pin through the
hole in the face of the chuck. It is a pretty small diameter. If I
had hit it any harder I would have bent the drift. I have to declare
innocence since I did not know about wedges. I also got word from
another list that Jacobs has all kinds of hints and such on their
web site. Will have to check that out. Fred (4097) |
| Fred, Check with
someone like Enco or J L for the wedges. They come in specific sizes
to fit each chuck. They're the best solution but only work if the
arbor has a shoulder they can seat against. As to the drill drift
method. I can't tell you how hard I wailed upon the drift I used. I
bent the first two then gave it up and used a piece of drill rod and
the largest hammer I had. I'd put the thing in a 10 ton arbor press
and used a cheater bar on the handle and still couldn't budge the
thing. In the end it simply took a great deal of force to move it
out. I spent 3 days straight working on mine before frustration gave
me the strength to knock it out of there. Dave (4101) |
| I guess out comes
the 13 pound sledge. Fred (4102) |
| Fred, The ONLY
other way that comes to mind would be to cut the arbor off flush
with the bottom of the chuck. Chuck up a piece of drill rod in the
lathe and the grab the protruding end with your Jacob's chuck. you
could then center drill it and *very carefully* bore it back to the
original diameter. Dave (4104) |
| Stuck Chuck!
Help! |
| My 13" South Bend
has decided it really likes the 4 jaw chuck presently stuck to it.
It has the 2 1/4" 8TPI mount and the chuck was installed about 6
months ago. I've tried bumping it (lowest back gear, reverse) with a
2x4 long ways through the jaws and nothing. Jeff (9151) |
| Your chuck has right hand threads.
Are you
turning it the right way? When my chuck sticks, I use a large
adjustable wrench. Clamp it on a jaw, back gears engaged, and hit
the wrench with a lead hammer one good blow. Watch your knuckles and
don't bang the ways. Oinkle Tom (9152) |
| Jeff, Try the lathe
in back-gear and using a strap wrench. If you have to place some
valve grinding compound between the strap and the chuck, that is if
the strap slips. Mike (9153) |
| I open the jaws and
use a 2x4 or a piece of aluminum flat stock between the open jaws.
First engage the back gears but don t pull the pin on the front to
lock the spindle. max (9154) |
| Jeff, a couple
months back I had a stuck chuck and I ended up busting 3 teeth off
my backgear while trying to get the chuck off with brute force.
After I busted the gear I still didn't have the chuck off so I took
the time to do it right. You might try this. Make a wrench to hold
the end of the spindle at the far left side. I took a bar of
aluminum 2 by 3 by 6 inch long and bored a hole through the side of
the bar close to one end. Then I put a split through the end of the
bar into the bored hole and then I cross drilled and tapped for a
clamping bolt. So I slid the makeshift spindle wrench onto the end
of the spindle and then tightened the clamping bolt. I had the other
end of the bar drilled for a cheater bar that I used a long bar
wedged against the floor. Then when I got rough with unscrewing the
chuck it didn't put any strain on any gear. Steven (9163) |
| My favorite is to
hold a wood block against the rear shear and spin the chuck (spindle
out of gear, belt loose) in reverse smacking a chuck jaw on the
block. The spindles own inertia unlocks the stuck chuck every time.
RichD (9166) |
| Here's a trick I've
done when all else fails. I get one of the wife's old nylon
stockings and a bowl of ice cubes. I put the ice cubes in the sock
and with a wooden dowel I push the icy filled sock down the spindle
with the jaws closed. Let it sit for about 2 to 3 minutes. Open the
jaws and close down on a piece of skookum flat bar. Then I give it a
big rap with a heavy leather hammer or a heavy dead blow hammer.
Lets go every time. (9169) |
| How about a little
heat? Oinkle Tom (9187) |
| I haven't even
worked on it again. Ill probably get in the shop tonight and give it
a go with several of these great ideas. I have a forced air kerosene
heater and I thought I might try heating the chuck up a little
first. Jeff (9188) |
| The ice in the
stocking idea sounded great - but why not get a chunk of dry ice
that you can put into the spindle right where the chuck threads on.
It'll chill the spindle quickly and really shrink it Frank (9194) |
| Tonight I
tried to free my stuck chuck again. I applied low heat to the back
plate, chilled the spindle with ice water, Clamped a 16 inch
adjustable wrench to the chuck and gave it a whack with a dead blow
hammer. The result. Sheared the cone pulley key and the chuck is as
stuck as ever. I guess I'm going to remove the chuck from the back
plate, apply some real heat with oxy/acet and try a big strap wrench
around the back plate. Now I know why they don't use large threaded
spindles anymore. Jeff (9221) |
| Remove the chuck.
Hose down the backplate/spindle contact area real good with a
penetrating oil. We use GIBBS here from the spray can. Let it
set for a couple days; repeating the oil. Then; install a stud into
the plate, and tap it around. Oftentimes; just removing the chuck
will do it. If it still won't budge, machine it off. Backplates are
cheaper than spindle parts, and much easier to find. In my
experience; the application of heat has seldom accomplished
anything. Threaded spindles fell out of favor for accuracy,
production speed, and increased operations where the spindle was run
in reverse. The chuck should be removed when not in use. (9224) |
| Jeff; I'm
assuming you've done the usual rust buster/ Kroil/ Gibbs penetrating
oil thing without success. With that effort assumed, here are a few
things that have worked around here. We had a badly stuck 4 jaw (13 incher or so) chuck on my neighbors SB15. We removed the chuck from
the backing plate, and bolted an 8 foot length of some metal (I
think we used 2 inch angle iron, but it's been a few years) to the
backing plate. A large strap wrench was wrapped around the cone
pulley and held by my neighbor using a length of pipe so I didn't
just lift him into the air. I stood on the end of the bolted on
breaker bar - being a petite 270 pounder this gave a fair bit of
torque. The backing plate still didn't move until we had my son tap
(not beat, just tap firmly) on the backing plate all around the
opening with a 3 lb ball peen. The combination of steady torque and
a little vibration did the trick. As the cone pulley key is sheared,
you may have to pull the spindle and hold it in a vise using
something similar to a gunsmiths barrel vise fixture. Basically,
this is a pair of soft jaws for the vise bored to take a cylindrical
item (barrel, spindle, same idea, just the spindle is shorter and
has a larger bore than most barrels.) If this doesn't work, then
you'll probably have to machine the backing plate off of the
spindle. You don't have to turn all the metal to swarf, just go in
with a parting tool in front of the register. As soon as the parting
tool gets through the backplate, the tension springing the threads
will be relieved and it should spin right off. Once it's all sorted
out, check the mating of the old (or new if it goes that way)
backplate and register with some bluing. Stone or scrape any pips on
the backing plate so you get at least 70 percent contact area.
Chucks get stuck this hard only 2 ways - accidental reverse
corrected by forward - makes a nasty bang and springs the threads
pretty hard, or from poor fitting of the backplate creating a spung
condition. Hopefully you won't have to turn off the back
plate. Stan (9233) |
| I guess I should
have said, don't heat the chuck up. I never do and just use ice the
odd time it has stuck. If you heat the chuck it expands internally
as well as externally and then your defeating the ice pack method
and just seizing it on that much worse. This was all explained to me
by a old Caterpillar mechanic one time who said that in some cases
that was the only way was to use ice. Well you'll say, I've heated
nuts that are stuck on bolts and they came loose!! What happened
here is you cracked the rust and crud seal between the bolt and nut,
then literally permanently expanded the nut and it breaks loose.
Have you tried putting a bolt in the chuck, putting a strong impact
gun to the bolt head and then have someone whack it with the dead
blow hammer? (9234) |
| Imagining the inner surface of a donut expanding radially inward
with heating is a common misconception which seems entirely logical
on the surface but in actual fact doesn't reflect reality. Expansion
of *any* point on either a solid or cored disk (doesn't matter
which) comes right out of the expansion equations - all radially
*away* from the center if the entire disk is soaked at a higher
temperature. However, a simpler example is the efficacy of a bearing
heater, used on spindles and other precision shafts to get an
interference fit. I just finished putting some new spindle bearings
on my HLV-H and used both a chilled spindle and a bearing heater to
slip them right on. The problem here is to get enough of a
temperature *gradient* across the joint to promote any real
differential radial movement of the internal and external threads
away from each other. The temperature coefficients of cast iron or
steel are small enough that it takes quite a differential to see any
significant results. Sometimes it's the only way, with a torch on
the outer surface and chilling in the middle, but geometry of the
joint often makes this difficult to do. Clever use of wet rags and
metal shields can help. Stan Stocker gave you the best alternatives,
especially with the key sheared. That is one stuck chuck! Mike (9238) |
| Whatever was the
resolution of the famous "stuck chuck" Please tell us what happened!
And how you un-stuck it. Frank (9314) |
| After trying many
things to remove the threaded back plate I've built a fixture that
mounts to it. This fixture has a 3/4 inch drive socket welded to the
center of it. Every other day or so I approach the lathe hit the
mount area with a liberal application of penetrating fluid and give
it 20 or 30 seconds worth with a 3/4 Ingersol Rand Impact Gun (max
on this gun is about 900 ft lbs of torque). I hold the opposite end
of the spindle with a Ridgid type strap wrench. I also tap around on
this fixture with a ball peen hoping to break the lock. This stuck
back plate is a perfect mate to the chuck it came with (South Bend
Stamped) but enough is enough. I'm about ready to machine it off and
make a new one. I might try one of the Ebay 21/4 8TPI plates I see
there and then Ill only have to check for flat, drill Thread the 4
mounting holes, and machine the dia. Anyway, this is where I'm at
with the problem. Has anybody tried those
already threaded back plates regularly on Ebay? Jeff
(9321) |
| Jeff: I haven't
tried one of the eBay plates, but I would caution you about the
import stuff (which this probably is) I have a Bison chuck that came
with a pre-threaded plate, It is not a good fit on the spindle nose,
and when parting off, I have to be very careful not to overload the
chuck, as the job will crawl up on the tool. I believe this is
caused by the loose fitting backplate. (doesn't happen with the 4J) I
plan to get a blank plate and machine it to fit the spindle nose
better. If you do buy a "eBay" backplate please post a review. Pete (9323) |
| Thanks to the many
here who gave suggestions.
With my father helping, I put a little heat to it, he used a 3/4
impact with a fixture bolted to the back plate while I hit the
fixture at the edge with a hand hammer. We were also holding the
opposite spindle end and finally it broke free. This happened after
two weeks of penetrating fluid application. When I separated the
parts two things were present, surface rust (condensation I suspect)
and it was thoroughly soaked with the penetrating fluid. I'm
removing the chucks when not in use from now on my lathes. Jeff (9356) |
| Jeff, Congrats .
And a word to the wise. If you are going to remove the chuck when
not in use do something to protect the threads of the headstock. It
is not hard for you or someone else to damage them and then you will
be filing them to straighten them out. Mike (9357) |
| Either that or just
leave the chuck on but use a dab of anti seize that's what I do and
have never had a chuck get stuck. Kerry(9358) |
| Stuck chuck |
| John, If the
generous application of Kroil super weasel wizz isn't doing it then
you may have metal chips stuck in the chuck backing plate threads.
It might explain why the Kroil doesn't seem to help. This is all too
common a problem. They can be cleaned out with a internal thread
restoring file and some elbow grease. A chuck should be threaded on
fully with only hand pressure otherwise it is has dirty or bad
threads. The metal swages itself into the threads. Fortunately the
spindle is harder than the chuck so it is usually saved. This
doesn't help getting the chuck unstuck right now though. You might
want to try bolting a piece of flat stock or angle iron to 2
opposite holes in the backing plate and hitting this with the
hammer. Not a sledgehammer blow but repeatedly like the impulse of
an impact wrench. The metal bar will transfer the impulse better
than wood. I believe that the backing plate (spindle adapter) is
made of cast iron so it is breakable but easy to replace. Don't
attempt to lock the bull gear, it is also cast iron and can be
broken and is not so easy to replace nor is it cheap! JP (16519) |
| JP, et al.
Good phrase-making! I'm favorably impressed with the Kroil, as it
helped a couple of other problems around the shop, even if it hasn't
unstuck this chuck yet. I fear that this lathe had an accident in
which a chuck jaw struck the compound. There's a chip out of the
front of the compound near the toolpost slot. Such an accident could
have galled the threads and just about welded them together. hammer.
impact I will try this. Will also try the air impact wrench
suggestion, both working against only the inertia of the spindle
step pulley. I know that dimensional cast iron stock can be
obtained, though I don't know the range of sizes available. Making
this plate would need a 4" circle of four 5/16ths (or so) threaded
holes centered exactly around the center hole. Probably a simple job
for an experienced machinist with a fully-equipped shop, but rather
difficult for a piker like me with only this lathe and a common
drill press with an X/Y/rotary table. Or, were you thinking I could
get a roughed-out plate somewhere, and just turn the O.D. to match
the back of the chuck? This is a Skinner Chuck 4207 chuck. Skinner
Chuck was in CT, but they have dropped out of sight. Do you have an
idea of another company's backplate that would fit? Yeah, I'd better
to go easy on that bull gear and the spindle. I got to thinking
about how bad I'd feel if I destroyed this fine old machine. It's
only a hobby - no need to be in a hurry. BTW: I can't get the serial
number cross-reference to open. (Probably my error.) The S/N is
17654. It has a single-wall apron, which pegs it as a Series O or
possibly earlier. The brass plate does not show a model number. Does
the two-digit number stamped on the spindle collar mean anything?
(Can't recall that number right now.) John
(16520) |
| On physical force:
are you statically loading the plate to try and remove it? that may
not cut it. you need the shock to break the bond. have a helper use
a cheater to apply firm pressure to unload the threads. Use the
WHOLE chuck mounted to the backing plate. Bolted angle iron, chuck a
piece of stock and use a large wench, etc. Basically have them
put their body weight into it. Then use a medium ball peen/ drilling
hammer to give it a good whack or two. thing is I seem to recall
that you may have sheared the locking pin? on galling: I don't
believe that there is much of a chance for the cast iron back up
plate and steel spindle will gall by themselves. The cast is too
brittle and effectively well lubed by the free carbon as a casting.
The worse risk is dirt or chips as it was pointed out grinding and
then keying the two together. this sounds like more the case, but
the cast won't furrow like the steel will. Tie off the spindle, take
a sawzall to the backing plate and cut out a pie wedge. Then you can
crack it off. as far as source for new backing plate, you could go
with a piece of durabar. Great stuff to work with. otherwise you
could get a blank or semi machined plate to replace the stuck one.
Dennis (16523) |
| Hold the pulley
with the strap wrench when you add an impulse to the plate. Adding
the chuck back on and using the impact wrench might absorb a fair
percentage of the impulse. The compound hitting the chuck is also
fairly common. The spindle threads are hardened and polished so
galling may not be it. My lathe came with a 3 Jaw that was tight.
After I got it off I raked the thread with the thread cleaning gizmo
shown in HTRAL. It didn't do much. I got a thread chasing file from
McMaster's and I cleaned out brass chips that were not visible at
all with a magnifier. Somewhere along the line someone was in a
hurry and spun the chuck on with the crap in there, probably a
number of times. The lathe came from a school in Boston. It goes on
easy now. For the backplate you can get a machined and threaded one
for about $50 new, made in Poland. From there you can turn down the
OD to fit and drill your holes. Cast iron should be rough machined,
aged and finished machined. The first two steps are already done. A
Bull gear is around $400. Glossary: Weasel wizz - anything that
frees up stuck parts (less polite terms acceptable) Urchin glop -
gooey stuff that sticks things together Gorilla snot - waterproofing
agent like butyl rubber undercoating Additions to the list accepted.
JP (16524) |
| I don't
know if this was already suggested, but a friend of mine had stuck
the chuck on his Heavy Ten and the only way we could get it off was
to use a parting (cut-off) blade in a left-hand parting blade holder
and machine the backing plate off just before the shoulder on the
spindle. If the chuck is "spun-on" or "crashes" into the compound,
the chuck gets wedged on very tightly indeed. Set the parting blade
about .020" to .030" to the right of the joint between the backing
plate and spindle shoulder so you won't hurt the spindle. Be careful
not to cut through and damage the spindle! Usually though, when the
blade gets close to cutting through to the spindle, the parting
blade will jam. This is because the "crush" between the spindle
shoulder and the backing plate to relieved and the kerf of the cut
collapses on the blade, causing the blade to jam. At this point,
what is left of the cast iron backing plate in the kerf is so thin,
it breaks easily and allows the chuck to unthread. After the chuck
is unthreaded, what is left on the spindle is just a thin washer
that isn't threaded and just comes off. If you are careful, there
usually enough left of the backing plate that you can reface the
"new" shoulder and reuse the backing plate. You can do this by
removing the chuck from the backing plate and mounting the backing
plate backwards on the spindle and taking a truing cut. Webb (16525) |
| Rough, cast iron,
back plates are available from ENCO. You can get them unmachined or
pre-threaded (pricier) for common spindle threads. Other than
cutting the internal threads the rest of the process for fitting a
chuck is not bad. (16528) |
| if you can take
your chuck and put it in muriatic acid that will clean out the chip
in the threads then after you get it off put your chuck in oil to
kill the acid. (16530) |
| Panther Pizz - Western Iowan for Weasel wizz Elephant snot - High
octane Gorilla snot used in the electronics industry. Polyrazamataz
- Plasitic of unknown ancestry. Glen (16531) |
| After entering the
number click on the tabs at the bottom to view the graph. JP (16536) |
| I'd add that the
kissing cousin of this procedure is used by gunsmiths to free up
barrels of old rifles that are stuck in their receivers - often the
barrel is to be discarded, but if done properly can be re-used.
(Called "setting back the barrel a thread"). It would seem to have
general applicability as a method for breaking the most persistent
of stuck threads, particularly when one part is largely expendable
or has spare metal and the other precious or fragile or both. Dave (16564) |
| Stuck Jacobs
Chuck |
| I'm trying to
remove the arbor from a Jacobs chuck and am not having much luck at
it. The chuck is a No. 34 (not 34-02, 34-06, 34B, just 34). The
arbor has a groove in between the Jacobs part and the Morse taper,
which leads me to believe it is a taper chuck, not a threaded one. I
also measured the diameter of the arbor where it goes into the chuck
and it's within a couple thousandths of a number 6 JT. I purchased a
set of removal wedges and they don't work at all (slip right out of
the groove on the arbor, applying no force whatsoever between chuck
and arbor). I drilled a hole in the bottom of the chuck and tried to
drive it off with a punch. No movement at all. What's one to do?
Could this be a threaded chuck? If so, how do you grasp the chuck to
loosen it without doing damage? Ralph (21558) |
| You got
2 possibilities. 1. It's a taper an well stuck at that, 2.It's a
thread that is well stuck. Now what do you need to remove the shank
for? You'll get lots of help here. The guys will say try heat, heat
and cold, heat and force, and spam with spam and spam, oops! Sorry!
Where's my drugs JP!!? The thing is, you may have to use force to
detach part 'A' from chuck 'B'. Tools like hardwood mallets are
great for this kind of thing. Almost everyone will suggest soaking
the piece in some kind of solvent first. We all don't like laying the
limb on venerable tool. Pressing is a good idea, (if it's not
threaded of course). A Dake brand arbor press is a real help in any
shop. Ron (21561) |
| Heating the chuck
and freezing the arbor with dry ice might change dimensions enough
so you can persuade it a moderate hammer and drift. JP (21564) |
| if you already
drilled a hole why not tap it and use a bolt to push the arbor
out(21566) |
| In using the
wedges, did you place them opposite each other when you tried
them? ie, grooves facing each other and then tapping with hammer?
(21567) |
| Drill for a pin
below the chuck for the wedges to ride against, that should work.
Jim Sterner recobb1128 wrote: I'm trying to remove the arbor from a
Jacobs chuck and am not having much luck at it. The chuck is a No.
34 (not 34-02, 34-06, 34B, just 34). The arbor has a groove in
between the Jacobs part and the Morse taper, which leads me to
believe it is a taper chuck, not a threaded one. I also measured the
diameter of the arbor where it goes into the chuck and it's within a
couple thousandths of a number 6 JT. I purchased a set of removal
wedges and they don't work at all (slip right out of the groove on
the arbor, applying no force whatsoever between chuck and arbor). I
drilled a hole in the bottom of the chuck and tried to drive it off
with a punch. No movement at all. What's one to do? Could this be a
threaded chuck? If so, how do you grasp the chuck to loosen it
without doing damage? Ralph (21568) |
| If it's a 6JT arbor
than you need a pair of #6 wedges. If used properly they will pop
the chuck right off. Ed P (21571) |
| Put the lathe in
low gear then an adjustable wrench on a jaw under that wrench a
large block of wood and that wood is resting on the ways on the
lowest gear or belt speed hit reverse and and turn off it should un
thread - If the chuck is a d-1 the pins may be able to turn 360 past
the ball plungers to open the cam- If its an l type spindle build a
spanner out of aluminum or steel that is a split in half put both
halves on both sides on the key ways and lock or re pin the spanner -
the spanner will look like a magnifying glass frame the handle rest
on the wood as from above- and if its an "a" spindle cut the nuts on
the back side of the back plate pull off the chuck or drill out the
screws (21578) |
| I was
finally able to get it off, by using the wedges properly and a bolt
threaded through the bottom of the chuck. There was a galled spot at
the front of the JT. After disassembly, cleaning, and stoning, I
reassembled the chuck and installed a new arbor. It had about .015
runout before and now only has about .0025. Opens and closes smooth
as silk too. Ralph (21602) |
| Stuck Chuck |
| I am starting the
teardown on my heavy 10 and have discovered that the chuck is stuck.
I cant seem to get it off. It's a threaded spindle
(21608) |
| Place a bar in the
jaws of the chuck sideways so that it sticks out towards you and
give it a rap with a lead mallet or brass bar.
(21610) |
| Why is it exactly
that you should not use the chuck key? I stopped doing this when I
read that but am still curious. Does it put too much strain on the
screws or what? Kevin (21617) |
| Kevin, It strains
everything and eggs out the hole the chuck key goes in. Think of the
chuck as a very precise tool like a micrometer or dial caliper. The
better you treat it the more accurate it will be. It also puts all
the pressure on one point of the diameter thereby requiring more
force to free it. Paul (21620) |
| In some cases the casting will shatter. On a single pinion
chuck this will render it useless. A strap wrench is the gentlest
thing to use on a stuck chuck. Another way to turn a chuck is by
putting a piece of stock in the jaws, Square in a 4 jaw and hex in a
3 jaw, and turning the stock with a wrench. I have a 1" Allen wrench
that works great with a rubber hammer. (21643) |
