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View Full Version : Proper way to remove a chuck from a threaded spindle



12teethperinch
12-19-2012, 11:33 PM
So I understand it's poor practice to use the back gears to lock the spindle when removing a chuck, but it's what I've been doing. Just wondering what's the correct way. I've got tons of machining books but I don't think I've ever seen the proper way.
Darrell

Dr Stan
12-19-2012, 11:53 PM
Well I'll probably get flamed, but that's the way I was taught in the Navy's Machinery Repairman School and have used that method ever since. Not once have I broken a gear in the process.

Ohio Mike
12-20-2012, 12:02 AM
I do it all the time. Now, that being said I don't get out the 36" Rigid pipe wrench and jump on it with a pipe. A chuck should come loose with firm even pressure. I only recall once when it really didn't want to come off. For ones that are really stuck I made a large 36" long spindle wrench for the South Bend Heavy 10 as I had purchased a machine that hadn't had the chuck of for what may have been most of its life. That one was really on there.

+ or - Zero
12-20-2012, 12:26 AM
At least on old Atlas's and maybe other lathes, it's the pin that locks the front gear to the stack pulley that is taking the beating (such as it may be), yes you start seeing it in the back gears, but it's one of the reasons (not the only reason) that pin starts getting sloppy.

Correct way to get the chuck off --whatever works and doesn't break anything --including the person removing the chuck (don't cross chuck a 2x4 and turn on the machine in reverse to loosen it for you --hey there are such people out there... for awhile anyway).

OKChipmaker
12-20-2012, 12:40 AM
Chuck a large bolt, then use a rattle gun on the ones that are stuck.

oldtiffie
12-20-2012, 12:47 AM
If I had a screwed-nose/s aspindle with a serioulsly jammed on chuck I'd really consider unbolting/removing the chuck from the back-plate and removing thr back-plate by turning it down to the outside diameter of the spindle and if it didn't come off then, screw-cut the remnant until it was easy to remove or almost falls off.

Knocking the back-gear train and the pin (and the holes on the gears for it)about will not improve things much at all.

Even though you've used a "cheater bar" "lots of times before", if you snap a gear tooth or the pin and the chuck is still on the spindle you might wish you'd made a spare backing-plate and removed the jambed-on plate as above.

"Bruised" back-gear teeth can be the cause of a "pattern" on an otherwise good job.

Having other "bruised/weakened" teeth" or the "pin" let go or snap sure isn't going to improve you, your lathe or you job.

darryl
12-20-2012, 01:36 AM
The spindle on my lathe has a collar behind the threaded portion. On the face of it is the register surface, and around the outside of the collar there are three holes. These are meant for a wrench of sorts that lets you hold the spindle stationary while you remove the chuck. No forces get transferred to any gearing or pins.

Your lathe must have something for a register surface, so it's quite possible you have these holes also- if not you could either drill some and make a wrench to suit, or maybe make a gripping device that would clamp around the collar tightly. As far as the chuck being so tight that it won't loosen, I'm with the camp that says don't beat on it. I don't like the idea of prying against the jaws either. I'd be more inclined to make a semi-circular tool that would notch into one of the pinions, then wrap about halfway around the chuck. Here you'd be putting pressure sideways on the pinion, which isn't going to hurt anything. You're not bending it, just hooking the tool into it. I don't know what that tool is called- bicycles use them for the bottom bracket. Something similar is called a pin wrench.

Paul Alciatore
12-20-2012, 01:41 AM
A word of caution here. I use the "lock the back gears" method and normally use a chuck key for leverage. I may hit the chuck key with the palm of my hand, but that is the limit of striking. If that fails, I will cross chuck an 18-36" wood scrap for leverage and apply pressure to it until it loosens. Here is the caution: do not strike the lever arm with a hammer or other heavy object. Want to know why not? Just look at used lathes on E-bay and count the ones described as having a broken tooth on the back gears. There are a lot. A sharp blow with a hammer will instantly apply a heavy shock to one or two gear teeth and this is very likely to break them. Wack: Snap! These gear teeth are intended for moderate, steady loads, not sudden shocks.

winchman
12-20-2012, 02:18 AM
Take the largest size pipe or tube or solid round bar that will fit inside the spindle. Taper the ID on one end, then make lengthwise slits. Weld a long handle on the other end.

Fashion a tapered plug with a threaded hole in the center. Install it with a bolt that can be tightened from the outer end of the pipe/tube/bar.

Slip the assembly into the spindle, tighten the bolt to expand the inner end, and you've got a nice handle to hold the spindle while you break the chuck loose.

lbhsbz
12-20-2012, 03:32 AM
I used to just leave it in whatever gear it was in, insert a chuck key and give it a smack with a rubber or plastic mallet. Worked every time, and I figured since it was a relatively soft mallet...no harm done. Never hurt anything either.

vpt
12-20-2012, 08:39 AM
I put my atlas in back gear to remove the chuck. But like mentioned I only use the chuck key and my hand to loosen it. Haven't had a stuck chuck yet.

Tony Ennis
12-20-2012, 09:13 AM
My Atlas's 4-jaw was stuck tight, probably had not been off in a long time. I finally resorted to engaging back gears, clamping a 2x4 in the chuck, and whacking end far end of said 2x4 with a 3lb sledge. Finally, about the time I was were going to give up, it moved a little. It screwed right off then. The threads were clean as a whistle.

Rich Carlstedt
12-20-2012, 11:48 AM
Please don't use the back gears !
If you must, use a wedge of soft wood, like pine, between the gears
The bearings are stronger than a Cast Iron tooth and the force is spread over several teeth !
If you have to take the cover off the headstock, so be it , at least you preserve the integrity of the gears.

If the stuck chuck happens more frequently , better check the clearance between the spindle shoulder and the c'bore at the back of the chuck ( this area is sometimes reffered to as "The Registration" ..which it isn't IMHO) To tight a clearance will cause stuck chucks.

Rich

Rosco-P
12-20-2012, 12:32 PM
Please don't use the back gears !
If you must, use a wedge of soft wood, like pine, between the gears
The bearings are stronger than a Cast Iron tooth and the force is spread over several teeth !
If you have to take the cover off the headstock, so be it , at least you preserve the integrity of the gears.

If the stuck chuck happens more frequently , better check the clearance between the spindle shoulder and the c'bore at the back of the chuck ( this area is sometimes reffered to as "The Registration" ..which it isn't IMHO) To tight a clearance will cause stuck chucks.

Rich

+1 on the above. Hardwood wedge between headstock casting and the spindle gear. If you think this put undue stress on the headstock casting, it doesn't. This is what I was told by a former employee from the Sheldon Lathe Co.

Forestgnome
12-20-2012, 12:35 PM
Chuck a large bolt, then use a rattle gun on the ones that are stuck.
Seems to me that would be hard on the chuck.

Forestgnome
12-20-2012, 12:36 PM
I always use the backgear, but I make sure I never cause an impact load, just a slowly increasing pressure.

Wirecutter
12-20-2012, 02:20 PM
I use the backgear, and on some occasions, a couple of taps from a rawhide mallet. I really don't think I ever get enough torque on my little belt-driven lathe to get a seriously stuck chuck.

Whenever I get in a situation where I realize a lot of force might be applied, the hairs on my neck stand up. I start asking myself "why" and "Self, are you sure about this?" If something breaks, where's all that energy going to go and cause damage? There's usually a safe, less risky way to get from A to B.

We're usually more likely to forget the above when tired or rushed. :rolleyes:

12teethperinch
12-20-2012, 08:24 PM
Thanks for the input. I wasn't talking about a really stuck chuck just everyday type of removal. Seems to me though that some clever engineer over at southbend cold have added a spindle lock . My little rusnok mill has a pin theft engages the pully so you can remove the collet from the spindle, I forget to undo it about half the time though, good thing it's a little motor.
Darrell

Orrin
12-20-2012, 08:30 PM
I have a method of removing the chuck that has worked for me every time, without fail. Furthermore, it cannot hurt the back gears, or anything else for that matter. Here it is:

1) Open the chuck jaws so there is an inch, or somewhat more, of jaw protruding from the chuck body. Don't allow the jaws to have more than half their length protruding.
2) Rotate the chuck so that a jaw on the far side of the chuck sticks out horizontally.
3) Measure the distance from the bottom of the jaw to the top of the ways.
4) Take a sturdy hardwood block---2" X 4" will do--and cut it to the length that you measured in step 3. You will only need to make one block for as long as you have the lathe. Save it for future use.
5) Stand the block next to the chuck , vertically, on the lathe's far side ways.
6) Rotate the chuck as far as you can toward you without a jaw knocking the block off.
7) Now, in the reverse direction, spin the chuck by hand as hard and as fast as you can so that a protruding jaw slams down on the block. The inertia of the spindle will tend to loosen the threads.
8) Repeat 6 & 7 a couple of times.
9) If the chuck has not freed up, yet, rotate the chuck to let the next jaw and slam it against the block. Repeat.
10) Continue working around the chuck from jaw to jaw as long as needed and eventually you'll "walk" it loose in the same manner that a heavy cut walked--or worked--the threads tight in the first place.

It takes longer to explain it than it does to do it. Unless the threads are rusted stuck; or, seized from dried oil and grease, it will come off. After getting a stubborn chuck off for the very first time, subsequent removals should be relatively easy.

I've encountered lathes that have set unused for 50 years. Everywhere, the grease and oil had hardened and set up almost like LocTite. I had no choice but to use heat until the metal was just barely too hot to touch; but, it was enough to soften the crud.

I have never used the back gears to remove a chuck and I've never broken a back gear tooth; but, I've owned a whole lot of lathes that had broken teeth when I bought them.

Orrin

winchman
12-21-2012, 02:26 AM
Lots of lathes have the end of the spindle sticking a little out of the headstock. You could grind recesses on opposite sides of the end of the spindle to fit the handle of a breaker bar that's got a hole in in like this one. You could also make the recesses to fir whatever round, hex or square bar you have available.

http://www.jimy.biz/catalog/images/41.SA35.12%20-%2012%20inch%20breaker%20bar.JPG

Open the chuck jaws, and use a large washer and threaded rod to hold the bar into the outer end of the spindle. Now you've got a handle to hold the spindle while you loosen the chuck.

I suspect most will disapprove of modifying the spindle this way, but it beats breaking the back gears when all else fails.

MrFluffy
12-21-2012, 05:04 AM
Day to day I put my lathe in the lowest gear it has, then put a long length of wood in the chuck and use it as a lever to wind it off, no hammers involved. On the few times its stuck, the motor goes round with the effort, at which point I wind it backwards then forwards to unscrew it against the intertia of the drive train.

Forestgnome
12-22-2012, 11:34 AM
Day to day I put my lathe in the lowest gear it has, then put a long length of wood in the chuck and use it as a lever to wind it off, no hammers involved. On the few times its stuck, the motor goes round with the effort, at which point I wind it backwards then forwards to unscrew it against the intertia of the drive train.

Several people have answered with similar methods. I would point out that if this breaks the chuck loose, then it puts the equivalent force on gears in the gear train as it would if you just locked the backgear. Now if the chuck doesn't break loose that's a different story. That's the point I would use a different method than locking the backgear.

jdunmyer
12-22-2012, 10:05 PM
Correct way to get the chuck off --whatever works and doesn't break anything --including the person removing the chuck (don't cross chuck a 2x4 and turn on the machine in reverse to loosen it for you --hey there are such people out there... for awhile anyway).


That would be me. There is no way to lock the spindle, so this is what I've done. Lathe is a 19" LeBlond, chuck is 10". I've broken a 2X4 when it was "flat" between the chuck jaws and had to put it in the other way. Using "copper" anti-sieze lube on the threads and register surfaces didn't seem to help.

That said, I've made a washer out of aluminum flashing and installed it between the register and the chuck. If that doesn't work, I'll try a washer made from thin gasket material, a reprint of a LeBlond manual suggests something similar. Still using the anti-sieze lube, of course.

Guy Lautard suggests making a thin washer from acetate and dissolving it with lighter fluid to remove the chuck.

+ or - Zero
12-22-2012, 10:41 PM
That would be me. There is no way to lock the spindle, so this is what I've done. Lathe is a 19" LeBlond, chuck is 10". I've broken a 2X4 when it was "flat" between the chuck jaws and had to put it in the other way. Using "copper" anti-sieze lube on the threads and register surfaces didn't seem to help.

That said, I've made a washer out of aluminum flashing and installed it between the register and the chuck. If that doesn't work, I'll try a washer made from thin gasket material, a reprint of a LeBlond manual suggests something similar. Still using the anti-sieze lube, of course.

Guy Lautard suggests making a thin washer from acetate and dissolving it with lighter fluid to remove the chuck.

I have a friend that had a 19" LeBlond Regal, he made a cam gadget that looked sort of like 4 large commas that would pivot outward on a center cam, each 'comma' was covered with a strip of conveyer belt cut to fit on it. the center cam was attached to about a 5 foot handle. He'd chuck a hunk of wood in the chuck, insert his cam wrench in the back end of the spindle and turn against the wood in the chuck which would be jammed against the ways. Always removed the chuck fairly easily, so far as I know.

Hope I described the wrench well enough to get the idea across, maybe it would work for you. Might be worth a try anyway --that 3" through hole was big enough to really get something in there to grab hold via expansion of the comma shapes --I don't think that approach would work so well with a small lathe.

He never said where he got the idea, I just assumed it was his personal solution to the 'that damn thing really grabs the chuck' problem.

darryl
12-22-2012, 11:32 PM
There's really two parts to this- one is how to safely prevent the spindle from turning, and the other is how to torque on the chuck body without damaging the jaws, their slides, or the scroll. Something like an oil filter wrench could be made up to handle the chuck body. Ideally you would not place any pressures against the spindle bearings, so the spindle should also have a handle that locks into it somehow. The two handles are then worked against each other to loosen the chuck. This is the same way that you tighten or loosen the collet on a wood router. One wrench for the spindle, one for the collet nut.

lakeside53
12-22-2012, 11:43 PM
Day to day I put my lathe in the lowest gear it has, then put a long length of wood in the chuck and use it as a lever to wind it off, no hammers involved. On the few times its stuck, the motor goes round with the effort, at which point I wind it backwards then forwards to unscrew it against the intertia of the drive train.

Yes, that what I used to do also on both my Emco V10p - use the motor. Worked very well - and much better on the gears than using any "shock force" like a hammer. Oh... the lathe didn't have a "back gear" so there was no "locking" available. And... the main drive gears were fiber, so no jambing wood in them!

jdunmyer
12-23-2012, 10:29 AM
+/-,
You've described your friend's arrangement very well, but my Regal is different, the through hole is much smaller, the O.D. of the spindle extension on the LH end is just 2 1/8" , the I.D. is smaller yet. I might be able to make something like the crank I use on the 7X Mini-Lathe, however. The spindle extension is right against the belt guard, so I can't even use something like a pipe wrench on it. There's no back gears as such, I just put the selectors in the 20 RPM holes. Seems to me like I'm not applying any more hurt to the drivetrain than those folks who use the inertia and wind it by hand. It takes 'this much' force to break it loose, no matter how you apply it.

It might help if I changed chucks more often, I'll regularly go years w/o switching. The 4-jaw is 16" and requires 2 people to man-handle it. Even the 3-jaw is heavy enough to be all one person can manage.

We'll see if the aluminum washer idea helps when I next do a chuck swap.

Daveb
12-23-2012, 01:07 PM
Hello everyone, I'm new here but I think this is relevant.
I bought a used Myford Super7 some time ago.
The seller said he had tried to remove the chuck but had given up, he wasn't really very talkative.
The chuck had a lot of hammer marks, the back gears and tumbler gears were toothless and the cast alloy belt
cover was smashed.
The price was low so I bought the lathe and replaced the spindle and other damaged parts.
Some time later, I set the old spindle with the chuck still attached in a vise and had a go at removing the
chuck.
Myford chuck bodies are bored and threaded, there is no seperate back plate so the old turners
trick (usually carried out in private) of unbolting
the chuck and turning off the backplate wouldn't work.
To cut a long story short, I tried everything, twice.
You will appreciate I was just doing this out of interest since I had already replaced the spindle and the chuck
had been beaten to death anyway.
Later still I set the spindle vertically in the bandsaw and cut down through the centre of the chuck.
Inside the chuck, threads, register and everything behind the scroll were rusted solid.
This was odd because there was no visible rust externally, the scroll and jaws moved freely and the rest of the
machine was like new.
If your chuck is stuck and you get to the point where you are hitting it with a hammer, and something else breaks.
I suppose it's possible that might be enough to push some people over the edge.
Personally, I always clean and oil the spindle threads before fitting a chuck.
Daveb

+ or - Zero
12-23-2012, 01:42 PM
+/-,
You've described your friend's arrangement very well, but my Regal is different, the through hole is much smaller, the O.D. of the spindle extension on the LH end is just 2 1/8" , the I.D. is smaller yet. I might be able to make something like the crank I use on the 7X Mini-Lathe, however. The spindle extension is right against the belt guard, so I can't even use something like a pipe wrench on it. There's no back gears as such, I just put the selectors in the 20 RPM holes. Seems to me like I'm not applying any more hurt to the drivetrain than those folks who use the inertia and wind it by hand. It takes 'this much' force to break it loose, no matter how you apply it.

It might help if I changed chucks more often, I'll regularly go years w/o switching. The 4-jaw is 16" and requires 2 people to man-handle it. Even the 3-jaw is heavy enough to be all one person can manage.

We'll see if the aluminum washer idea helps when I next do a chuck swap.

I see, and yes I agree that you are not applying any more force then anyone else is and possibly less shock impact (assuming the wood block is in solid contact with the ways to start with) --what would worry me is that using the motor, if any tooth did fail, you'd probably lose several teeth --that wouldn't ruin one gear any worse (one tooth or all, it's a dead gear), but it would at the very least put broken teeth down through the gear train, running quite a risk of destroying more then just one gear --or at least it seems that way at first blush.

And as you can get down to that 20 rpm speed you are not running much (if any) risk of the chuck spinning off before you can stop the spindle.

What I was actually talking about to start with was people with a small lathe that can't (not nearly enough power or low enough gears) just horse the power train with a locked spindle (by virtue of a jammed chunk of wood against the ways), who leave a gap between the wood and the ways so the impact caused when they start the motor causes the chuck to spin a few inches (as much as maybe 200+ degrees of spindle rotation, depending on the set it up) so the impact with the ways causes the chuck to break lose --or break something anyway.

I didn't see it happen but I knew a guy that ended up in the hospital with a chunk of the 2x4 he was using that way having to be removed from his cheek --not real serious, but missed his eye by about 2 inches, that wouldn't have been so minor. At least he never used that method again (that I know of, don't know what ever became of him, was long ago) --but he said he'd been doing it that way for 'years'... oh well. The only thing that really bothers me is the possibility of being anywhere near someone that might do something like that --could be my eye that's in danger.

jdunmyer
12-23-2012, 07:25 PM
Well, I do have the 2X4 away from the ways when I start the motor, but I generally hold onto the chuck lightly to remove the backlash from the gear train. When the 2X4 hits the ways in the rear, the chuck either comes loose or the 2X4 breaks. I've not had it fail if I put the 2X4 in the jaws the "strong way", but I have had it break if it was "flat". As you say, it's going slow enough that there's no danger of spinning the chuck off the spindle.

I'm not proud of it, and you guys can all be critical, but if you were in my position, you'd probably do the same. The trick is to somehow prevent the chuck from siezing onto the spindle. Some of the problem may come from the fact that the backplate is homemade, and is all-steel, not the usual cast iron. The previous owner made it, many years ago.

I've always cleaned and greased the threads and register surfaces when changing chucks, and never had this sort of trouble with my 2 Atlas lathes prior to this one. Began using the "copper" anti-sieze lube due to recommendations from (I think) here.

The Artful Bodger
12-23-2012, 07:28 PM
Perhaps an appropriate project for all users of a threaded spindle lathe would be an expanding plug for the outer end of the spindle that could take a long lever?

lakeside53
12-23-2012, 08:44 PM
All users? Not all spindles are strong at the rear end. I wouldn't do that on an Emco10 spindle.

mike4
12-23-2012, 08:48 PM
I looked a buying lathes with threaded chucks and found many were damaged in some way from the different methods used by previous owners over the years to swap chucks.

Its the reason my lathes are all camlock spindles, apart from the quick change of chuck , no worries if reverse has to be used for a job .

Michael

jdunmyer
12-23-2012, 09:00 PM
Bodger,
I am going to investigate an internal wrench of some sort, and your thought crossed my mind. I can just see my locking mechanism swelling the spindle tube and screwing up the bearing. Fortunately, there's quite a bit of that tube that's Left of the bearing, so a bit of distortion wouldn't hurt. Not nearly as much as breaking a gear. :-(