Stuck 3 jaw chuck

[flathead4]

Take a small chunk of 2x4 of a size to fit between a jaw of the chuck and the rear way, such that it will prevent the chuck from turning. Put the lathe in the absolute lowest reverse gear. Allow a couple of inches between the chuck jaw and the piece of wood that will keep it from turning. Bump the starter switch for 1 second, so that the chuck starts to turn but hits the wood and is prevented from turning further. Since it can no longer turn with the spindle, it will begin to unscrew.

Since you only had the motor on for a moment at at a low speed it will not continue to unscrew, coming off the spindle, clobbering the ways and then landing on your foot. You can now unscrew it the rest of the way by hand, with appropriate protection (a board) on the ways.

I wouldn't even do that with your lathe. I wouldn't have my lathe plugged in while trying to unstick a chuck.

Tom

[mickeyf]

Well, I understand that your lathe is a delicate precision piece of equipment that must be handled with kid gloves, and also that safety comes first. However,

1) Do you really disconnect your lathe every time you change a chuck? Does anyone? Show of hands, please.
2) Do you believe that this is more stressful to, and more likely to damage the chuck than using a large wrench, as has been suggested?
3) My observation is that unless you never take anything that could be remotely considered a "heavy cut" you will NOT be able to unscrew a thread-on chuck by hand. I suspect this may have been part of the motivation for the invention of the cam-lock chuck. Even a little 1/2 HP motor, especially when run through a set of back gears has a whole lot more power than I do.
4) What I have suggested is hardly new. Obviously opinions differ, as with whether compressed air has any valid place near a machine tool, but in fact it is standard practice in many shops and has been for years. Of course some judgment is expected. I hoped that went without saying. Starting Off, as pictured below, and no more, is what I was attempting to describe.
5) Until you have seen my lathe, you really shouldn't comment on it. You might want to put it out of its misery.

[flathead4]

Do you really disconnect your lathe every time you change a chuck?

Okay, you got me there. But I do try to unplug it if I have to fool with a stuck chuck.

Starting Off, as pictured below

I still don't think I'm ready to try it under power, but I'll have to try rotating the chuck into a block of wood like pictured. I looks like the operator is rotating the spindle by hand to whack a jaw on the wood block.

Until you have seen my lathe, you really shouldn't comment on it. You might want to put it out of its misery.

My condolences.

Tom

[mickeyf]

Yes, the picture shows someone turning the flat pulleys by hand, and this ancient textbook does say that's the first thing to try. I was only saying "if all else fails"... And too much of the time, all else does. I do think this is no worse, and probably better than "put a pipe wrench on the chuck jaw and whack it one", but in this case the lathe motor does the whacking.

[Willy]

I think the idea put forth by mickeyf has some merit, it's definitely worth a try. Of course in every type of rescue attempt like this, discretion and common sense should always remain a key focus point. I know, not always easy to predict what someone else's threshold for discretion is.

From what Dhamma mentioned in his first post about removing clamps that secure the backplate to the spindle, I will assume it is indeed a screw mount thread, probably a 10"x22" GO602.

I have worked on similar lathes in the past, several times actually for the same problem. What worked for me was to put a very large nut into the chuck with enough sticking out to get a socket onto.

Then do what ever you can do to lock the spindle as best you can, even a good strap wrench on the drive pulley if done properly will work. Some times you have to resort to two or three methods in conjunction to do this right, but securing the spindle is the key to this procedure working.
The reason it has to be as rigid as possible is because we will be using a 3/4" impact wrench on that nut in the chuck. Impact wrenches only work if they can strike a sharp blow, without rigidity in the setup none of this will work. Also unless the backplate and spindle are only slightly stuck forget about using a 1/2" impact, simply too wimpy. 3/4" minimum!

[Dhamma]

Mike,
It is a threaded spindle. Confirmed by the manual and the 4 jaw chuck I want to install. Although the quality of the threads visible on the 4 jaw chuck leave a little to be desired.

I guess no one is buying my theory that the difficulty could be contraction of the chuck due to cold.

Thanks for the suggestions
Jim

[moe1942]

[QUOTE=mickeyf I do think this is no worse, and probably better than "put a pipe wrench on the chuck jaw and whack it one", but in this case the lathe motor does the whacking.[/QUOTE]


And who suggested doing that???

[mickeyf]

Earlier in the thread...

I don't know about the Grizzly lathe, however I use the method that Flathead4 described.....with a minor exception: I put a 14 inch pipewrench on one of the jaws (with the backgear and bull gear engaged) and strike the pipewrech with a mallet. Since the chuck jaws are hardened, I have had no damage to the chuck using this method.

If such extremes are attempted, better a 2x4 than a pipe wrench.... And I suppose any damage would be to the chuck, not the lathe. The chuck, after all, is a mere accessory, and easily replaceable.

[moe1942]

Earlier in the thread...



If such extremes are attempted, better a 2x4 than a pipe wrench.... And I suppose any damage would be to the chuck, not the lathe. The chuck, after all, is a mere accessory, and easily replaceable.

Ouch!! Missed that one..

[Walter]

I am a green beginner. Here is my problem: My Grizzly lathe has a chuck I cannot get off. I have removed the clamps holding it to the spindle. It seems the threads are stuck. I have tried WD=40, etc.

Could temperature be the problem? It is in a unheated but insulated workshop and the temp probably gets down to the 40's. I am thinking about using a hair drier to warm the chuck on the theory that it will then expand and release itself from the threads on the spindle.

Thanks

Regarding your comment about removing the "clamps".... what are you referring to, no threaded spindle has clamps. Can you possibly post a pic of what your dealing with, failing that please describe the clamps your referring too as this really doesn't make sense.