Removing Chuck

P

porthos

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i know that this has been addressed many times but the answer "left me". what is the proper way to remove a tight 3 jaw from my south bend threaded spindle. just got done fitting a backplate to a new bison chuck and the only way that I could remove it was to put an aluminum bar 1 in. by 1/2 in between the jaws and smack it with a nylon mallet. I didn't jam it on tight when installing it. I wasn't cutting anything. I was setting it for runout with the bolts not tightened but lightly. I ended up with about .004 total runout. would greasing the threads help? also would rapping on the chuck with a rubber mallet be ok? advice??

porthos
 
Engage back gear but don't disengage the back gear pin that locks the pulley to the spindle. Put a wrench on one of the chuck jaws and turn CCW. If you are really struggling to remove it, stop using the back gears to lock the spindle and use a different method. It is possible to shear a back gear tooth if you really crank on it.

I clean and oil spindle threads every time I change chucks.
 
keep the threads clean, oiled and loosen the chuck regularly
i change between 3 and 4 jaw and collet regularly and the chuck simply doesnt get time to get stuck
 
Hi Porthos,

In my understanding you did everything 100% right! If you're not sure go easy.
In this case you went to the plastic mallet _NOT_ the 100 lb sledge.
Good call!

I often keep a piece of 1" cutoff wood near the lathe. I use that. Open the jaws enough to accept it and give it a little tap with a hammer.
I do not engage the back gear; just use the "inertia" of the spindle.

-brino
 
I had that problem a couple of times. Now I use wax on the spindle threads and it hasn't happened lately.
 
Charles Spencer said:
I had that problem a couple of times. Now I use wax on the spindle threads and it hasn't happened lately.

I've never heard of that. I might have to give it a try as some of my machines set for longer periods of time between use.
Click to expand...
 
Hi all. New to this forum, but I like the idea of waxing spindle threads...will have to try that one on mine! :)
 
Don't forget to place a piece of plywood or such under the chuck to protect the bed ways. Chucking a piece of pipe or solid stock and a pipe wrench might also help (not too big).
I never liked banging on machines, but I'm a rookie by comparison to many.
 
As far as removing your chuck when stuck, here is a link...

http://www.practicalmachinist.com/vb/south-bend-lathes/how-remove-stuck-chuck-tutorial-165028/

"I didn't jam it on tight when installing it. I wasn't cutting anything."

I'm thinking that the back side of the backing plate is not parallel to the spindle face behind the threads. This may have the effect of "wedging" the backing plate to the spindle, resulting in a stuck chuck. In addition, this may add to the runout you are measuring.

Brian :)
 
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