stubborn chuck removal on South bend lathe
- Thread starter bretk
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B
Bogstandard
Guest
Hi Bret,
If you have back gearing, select it, but don't disengage the normal side. That will totally lock up the head.
Get the largest piece of bar you have that will tighten in the chuck, as shown in the attached piccy. Try that. Don't put too much load on, as doing it this way can sometimes strip teeth off the gears. If it won't come off with pulling on the bar, a dead blow shock load will usually release it.
When really stuck, it is not recommended to use the normal practice of tightening the chuck up, and putting the key in the tightening hole and giving it a slight shock load with a dead blow hammer. That is usually only used for normal removal.
John
If you have back gearing, select it, but don't disengage the normal side. That will totally lock up the head.
Get the largest piece of bar you have that will tighten in the chuck, as shown in the attached piccy. Try that. Don't put too much load on, as doing it this way can sometimes strip teeth off the gears. If it won't come off with pulling on the bar, a dead blow shock load will usually release it.
When really stuck, it is not recommended to use the normal practice of tightening the chuck up, and putting the key in the tightening hole and giving it a slight shock load with a dead blow hammer. That is usually only used for normal removal.
John
mklotz
Well-Known Member
I had the same problem when my lathe was delivered. The 3jaw was mounted (apparently by a lowland gorilla) and was impossible to remove.
First, get some Kroil and dribble it into the joint where the chuck meets the spindle. A hot air gun to heat the chuck as this is done is also a good idea.
Rather than twist the jaws by gripping a leverage bar, I made a banjo wrench from 3/4" plywood.
The wrench distributes the torque on all the jaws.
I've used John's technique of locking the spindle by engaging the back gear but it scares me.
I'm always afraid that I'll hear a ping as a bull gear tooth lets loose. What I did was build a crank that grips the inside of the spindle with an expanding collet.
This gives me plenty of leverage to counteract the torque provided by the banjo wrench.
Depending on how locked your chuck is, you may not need all my suggestions but I wanted to add them to this thread so that future searchers of this topic will be aware of all the options that are available.
Finally, when you do get the chuck loose, oil the threads well before re-attaching it so this situation doesn't crop up again.
First, get some Kroil and dribble it into the joint where the chuck meets the spindle. A hot air gun to heat the chuck as this is done is also a good idea.
Rather than twist the jaws by gripping a leverage bar, I made a banjo wrench from 3/4" plywood.
The wrench distributes the torque on all the jaws.
I've used John's technique of locking the spindle by engaging the back gear but it scares me.
I'm always afraid that I'll hear a ping as a bull gear tooth lets loose. What I did was build a crank that grips the inside of the spindle with an expanding collet.
This gives me plenty of leverage to counteract the torque provided by the banjo wrench.
Depending on how locked your chuck is, you may not need all my suggestions but I wanted to add them to this thread so that future searchers of this topic will be aware of all the options that are available.
Finally, when you do get the chuck loose, oil the threads well before re-attaching it so this situation doesn't crop up again.
if all else fails, here's a note from the late great Robert Bastow....there's a guy who knew his stuff!
http://yarchive.net/metal/stuck_chuck_loosen.html
http://yarchive.net/metal/stuck_chuck_loosen.html
B
Bogstandard
Guest
Lovely stuff, the more ways the merrier.
There is always more than one way to skin a cat, just depends what recipe you are using.
By everyone showing how they do it, there should be a safe method for everyone, for each type of lathe.
John
There is always more than one way to skin a cat, just depends what recipe you are using.
By everyone showing how they do it, there should be a safe method for everyone, for each type of lathe.
John
DickDastardly40
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I had a stuck 3 jaw chuck on the first Myford I had from when I acquired it. Being brought up on camlock fasteners I was a little out of my depth and I was a little concerned about breaking the teeth in the back gear or a casting when clouting it so I disassembled the headstock and then tried a variety of methods to remove it.
The biggest problem was stopping the spindle from rotating without damaging any of the surfaces. I tried a pair of nuts locked against each other on the end of the spindle where the bearing preload is, but whilst it might have worked if they were close to the chuck the whole setup was too unwieldy when in the vice. I tried soaking the whole thing in penetrating oil, I tried twacking it with a mallet, I tried putting it in the Aga for an hour but was again foiled by the rotational issue even using a split copper pipe as soft jaws. I even shouted at it, it wasn't impressed!
In the end I made a split bush from some hex brass bar with a keyway in which suited the shaft of the spindle and was bored exactly on diameter to put in the vice and a used 4 foot length of scaffold pole on a spanner locked against the jaws. An irony was that I needed the tool I was fixing to make the part I wanted to fix it with. Unscrewed with a small 'pop' and disappointingly no accompanying fanfare. The thread was in perfect condition, I'd expected galling or somesuch, it had just been over tightened, god knows how.
I always put some oil on the thread when fitting a chuck now. Picture of the split bush to follow when I get home.
Al
Edit. Marv, I like your expanding handle, not sure it would work so well on a myford as the spindle bore is only about 5/8".
The biggest problem was stopping the spindle from rotating without damaging any of the surfaces. I tried a pair of nuts locked against each other on the end of the spindle where the bearing preload is, but whilst it might have worked if they were close to the chuck the whole setup was too unwieldy when in the vice. I tried soaking the whole thing in penetrating oil, I tried twacking it with a mallet, I tried putting it in the Aga for an hour but was again foiled by the rotational issue even using a split copper pipe as soft jaws. I even shouted at it, it wasn't impressed!
In the end I made a split bush from some hex brass bar with a keyway in which suited the shaft of the spindle and was bored exactly on diameter to put in the vice and a used 4 foot length of scaffold pole on a spanner locked against the jaws. An irony was that I needed the tool I was fixing to make the part I wanted to fix it with. Unscrewed with a small 'pop' and disappointingly no accompanying fanfare. The thread was in perfect condition, I'd expected galling or somesuch, it had just been over tightened, god knows how.
I always put some oil on the thread when fitting a chuck now. Picture of the split bush to follow when I get home.
Al
Edit. Marv, I like your expanding handle, not sure it would work so well on a myford as the spindle bore is only about 5/8".
DickDastardly40
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Try saying expanding mandrel handle several times very quickly! ;D
DickDastardly40
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Here's a couple of pics of my split bush:
Al
Al
The Chuck is Un-StucK ;D ;D ;D Thank you all for your suggestions, McGyvers link trick did it along with some kroil and a bit of prayer! Now I can use my 3C collets for my 1/4" square stock to make my clevisis (sp?) for the beam engine.
Thanks again for allthe advice, I am going to make one of those banjo wrenches for future use.
-Bret
Thanks again for allthe advice, I am going to make one of those banjo wrenches for future use.
-Bret
DickDastardly40
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joe d said:
Hopefully the statute of limitations has run out on purloining spoons as I've had it since my first real ship out of training in 1987. I swiped it off of the Deputy Marine Engineer Officers saucer when he left his cup loafing in the Ship Control Centre on my first day on board! ;D
I have mentioned earlier it is now out of calibration as there is a small flat on the tip.
Good news on your chuck Bret.
Al
mklotz
Well-Known Member
bretk said:
Glad to hear that you got it off.
Teenut was a fount of wonderful advice. That said, I still don't like the idea of using my lathe to bang things into the bed, no matter how much wooden lagging is interspersed. I'm pleased that you intend to make the banjo chuck. I'll sleep better knowing that.
