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Stuck chuck on Atlas lathe

S

sask3500

Member
I’m in the middle of setting up an Atlas lathe, a th54. I tried to remove the chuck for cleaning and it’s stuck pretty well. It was bad enough the little pin that stops the spindle broke off.

I use a heat gun to warm it up to maybe 200f, that didn’t help. Any suggestions? Especially tricks to safely hold the spindle without damage.

I’m assuming it’s just threaded on, no secondary locks.




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Sounds like you used the indexing pin as a spindle lock. you should be able to make yourself a new one once the machine is up and running.

according to an old manual, yes, your chuck is threaded on. You probably have the 1 1/2“ by 8 TPI spindle nose. Standard right hand threads.

i would use the v-belt on the largest pulley on the spindle and pinch it together by hand. Use a piece of wood and pry on the chuck jaws to try and rotate it counter clockwise while holding the spindle stationary with the belt. Cover your ways with wood as well to protect them.
 
Another way which I personally have not tried is to use the chuck momentum itself to break the threads free. Supposedly it works quite well.

Using a stout bar in the chuck and sticking out about two feet or so to one side like a handle, fling the chuck smartly backwards by hand so that the bar smacks sharply on the top of a 2x6 or something standing on end and braced off the floor. The rotation of the chuck will stop abruptly when the bar hits the 2x6, but momentum is often enough to loosen the stuck threads and doesn’t put any strain on the gears. This may help visualize the desired action...

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Not your Atlas lathe although what appears like a really tight chuck removal on a Myford lathe.


Bill
 
When I got my SB 10K I had a heck of a time getting the chuck off. I used the method @francist illustrated so well. I chucked up a 18" long length of 1" channel steel and put a couple of short pieces of 2x4 behind the lathe bed on my bench where the end of the channel would hit when I spun the chuck. I gave it a good swing and it came undone. Easy as pie.

Now when its snug I put the belt on the big pulley and slip a large-ish crescent wrench over a jaw and give it a bump with my hand it pops free.
 
Thanks for the replies, I’ll see if I can get it free when I get some spare time. It took me about a year to get it cleaned up, a stand built, leveled and anchored to the floor and wired up. So it might be awhile lol...


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Should you succeed in removing the frozen chuck kindly advise the list as to the process used as this is useful information for others.

Don't forget a few drops of oil on the threads before installing the chuck again.

Bill
 
Morning all, when I bought my SM I had the same stuck chuck issue. I tried the francist bar in the jaws and all the other tricks including heat with no luck. I ended up taking the chuck off the backing plate, removing the spindle and throwing it in the freezer overnight. In the morning I mounted a bar on the backing plate, clamped the spindle in the vice (soft jaws) and then added heat from the propane torch to the backing plate while putting my weight on the bar. After about 30 seconds of heat the plate finally moved and I was able to spin it off. What a pita! Now, as per Bill's suggestion, I lightly oil the threads and the register and just snug the chuck onto the spindle then remove the chuck when I'm done for the day. I'm not taking any chances of the chuck getting stuck again.
Mike
 
Yup, I'm really cautious about not over-tightening my chucks too. Oil on the threads as noted above is good practise, and I also use a narrow gasket of brown paper (cut from a brown grocery bag) between the chuck and spindle register. I read about that trick somewhere and it does seem to help.

Where the problem can sneak up on you is interrupted cuts -- they act a bit like an impact hammer and tighten the chuck just a tad more with each hit. If I'm doing a lot of interrupted cutting I try to remember to loosen off the chuck at the end of the work just to make sure it's not getting jammed on too tight. Of course none of this is a problem unless you have a threaded spindle...
 
Indeed. When I was cutting my backplate I did a facing cut across the full diameter which included the holes for the mounting bolts.
The slight shock of crossing the holes definitely snugged up the chuck.


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Could the uber tight chuck issue partly stem from a chuck that is running out of thread before seating on the back landing? So instead of the chuck resting on the shoulder as is required, it is wedging on the last thread?

just wondering.
 
Stupid question-

The chucks still open and close, right? Could you not chuck up a piece of hex stock or a large bolt and use an impact gun to loosen it?
 
Hex stock would work. I didn’t have any luck with chucking a large bolt as the bolt spins in the chuck. Or at least it did for me.


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Chicken lights said:
Could you not chuck up a piece of hex stock or a large bolt and use an impact gun to loosen it?
Click to expand...
That was one of the methods put forward in one of the videos -- I believe it is effective but I have not personally done it. A long "coupler nut" or "joiner nut" is a cheap and easy source of large hex material. Almost every hardware store that sells 3' lengths of ready rod will sell them.
 
Running out of thread - the impact gun should work for that one.
I tried the impact gun but it didn't work for me. From the gouges in the compound I think mine was just beaten on over the years of school use and I doubt it was ever taken off the spindle.
 
Another method is filling up the end of the spindle with dry ice. It may contract enough to get the chuck loose
 
Well I tried again today, a 3” section of 3/4 joiner nut in the chuck and a internal pipe wrench with a breaker braced against the base in the other end of the spindle. Then used a 1/2” impact on the joiner. No luck.

It’s a really old lathe that came from a farm, had bird leavings on it so I assume it wasn’t a dry heated shop. I suspect it was put together dry decades ago and has Mother Nature’s loctite in the threads now.

I’m pretty familiar wth getting stubborn stuff apart as I run a heavy truck shop, but I’m trying to be gentle here. It’s soaking in penetrating oil now, I’ll spray it down regularly for a bit and try again.

If it was a truck part I would have counted to ten with the 3/4 gun rattling, then reached for the sparkle wrench if it wasn’t moving or broken off yet. But I don’t think that would have been productive here...



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The dry ice might work, especially if the chuck is up to a couple hundred degrees first. Anyone know what the Zamak does when it’s heated and cooled?


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