UN-Stuck Like Chuck!

I created this thread in case some of you would be interested in how I finally removed the Cushman chuck from the spindle on my 1969 13". This was after about 3 weeks of trying to separate the two while the spindle was installed on the lathe. I really didn't want to remove the spindle, as I had just recently got it re-installed after stripping and painting my entire lathe, but after gritting my teeth, off come the bearing caps and re-disassembly began!!!

After a broken strap wrench, 2 sheared-off woodruff keys and lots of cussing, what finally worked was inspired by ideas from this forum, so I thought I'd share!





My setup started by boring a "puck" of aluminum, from an old hydraulic cylinder piston, to match the spindle diameter where the keyed gear goes on the left end of the spindle. I then split the puck through the radius on one side and carved out a 3/16" key slot to accept the woodruff key. I also machined some flats on the outside so I could squeeze the puck in a vice.


I then drilled out an old back plate that came with my lathe(didn't fit it though) to accept the bolt pattern for the back plate of my chuck. I also bored out the center of the drilled back plate to accept some 1-1/4" hex stock. I then welded the hex inside the plate to give my 1" air impact gun something to gnaw on. I must have torqued on that thing for 20 minutes after applying torch heat to the back plate with no sign of movement. At this point I'm about ready to cut the thing off!


After letting everything cool down, we brainstormed and came up with one final attack plan. We loaded up the inside of the spindle with ice cubes(my brother, Casey's idea!) and again applied heat to the back plate... lots of heat! The idea here was to try to shrink the spindle and expand the back plate and hopefully get something moving.


After whaling away with the impact gun for damn-near 5 minutes straight...SHE BROKE FREE!!!!!


The threads on the spindle look great, as well as the inside taper! I wonder if this chuck has ever been removed from the lathe?? The threads on the back plate seemed fairly rough and very sharp. My compound rest shows signs of several run-ins with the chuck throughout its life, so I'm guessing this had "impacted" the chuck on to the spindle. Also, the bull gear woodruff key was sheared when I got the lathe. Someone has been mistreating my old girl!

Thank you guys! Now... On with the build... Again!!

DAMN!! Good for you Cody. Thanks for the story and pics; very interesting.
Casey had a good idea it seems. Just goes to show how tough that spindle really is.

PMc

Did you ever try the weighted bucket method? That's where you lock the spindle (with the back gear), capture a rod in the chuck that extends horizontally from the chuck, then suspend weights from the end of the rod. Put as much weight as the rod can hold, then wait... After a day or two, a very well stuck on chuck sometimes breaks free.

Also, did you identify why the chuck was stuck in the first place? Often times, users will screw on a chuck feeling resistance to a smooth attachment. That resistance is usually due to swarf in either the chuck treads, or on the spindle threads. You should NEVER force a chuck on like that, as it can become a permanent attachment to your lathe. Cutting a washer out of wax paper or parchment paper (cooking paper) and placing this between the spindle register and the chuck can help keep the chuck from sticking.

And as always, the zero option is to simply machine the backing plate off the spindle.
Backing plate cost < replacement spindle cost

I certainly didn't try the bucket method. Would have been nice to try before the spindle came back out, but as much force as it took to separate the two, I feel like it wouldn't have been enough. The threads looked fine once I got a look at them.

The lathe is new to me, so I have no idea the full history, other than it possibly spent time in a classroom situation where it was surely abused. Upon reassembly I'll try the gasket method, as I'm hoping to be able to freely change chucks/collets with a minimum effort in the future.

Thanks again!

there is a trick that old time gunsmiths would do on the 1917 endfields them barrels can be in so dam tight that the threads come out with the barrel or the rec. or the barrel will twist so the trick in them is to set up the barreled rec. in a lathe and with a then parting tool undercut the barrel as close to the rec. as you can get without cutting into it so after that the barrel comes right off and if the barrel can still be used by cleaning up the undercut and making a shim to take up what was removed so in the case of the stuck chuck the same thing most likely would have worked by making a thin parting tool and parting just in front of the spindle and after that it would have come right off and then face off true up the mating surface of the spindle but hey in the end you got the chuck off and that's what you set off to do

congrats! The heat and cold trick really works well - I did that when pressing the bull gear off my spindle. Put the whole assembly in the oven at 300F while the wife was out, then stuffed a bunch of ice cubes down the spindle and it came off easily. Dry ice would have been even better.

Same works for press fits - heat up the big thing, cool down the small thing and work quickly!

1Yesca,
I did something close to that with the backplate that came on my lathe. I took a parting tool in a lantern holder and parted the backplate spigot as close to the flange on the spindle as I could. When I was getting close I heard a "pop" and stopped. The backplate then unscrewed pretty much by hand.
I was then able to remount the chuck with a shim to make a new backplate.

Rudd said:

1Yesca,
I did something close to that with the backplate that came on my lathe. I took a parting tool in a lantern holder and parted the backplate spigot as close to the flange on the spindle as I could. When I was getting close I heard a "pop" and stopped. The backplate then unscrewed pretty much by hand.
I was then able to remount the chuck with a shim to make a new backplate.

Click to expand...

ya the nice thing about doing it that way is you don't put all that heat and stresses in to that poor spindle and if you can make the tip of the parting tool thin enough mite get by with just refacing were the back plate sets up to the spindle the one good thing about this whole thing there were no back gear teeth harmed [broken off] in the processes of the processes

That was my final thought, I had tried the impact, the "clamp on the end of the spindle", a little heat, and finally asked myself if I really wanted to risk fubaring the spindle over a 50 dollar backplate. I've got the old cast iron spindle bearing headstock, so it would likely not be as easy as buying another spindle and dropping it in.

I built special tool number 112, cut the plat to fit the back plate bolt pattern, welded on some stout square stock, was scared to damage the back gears so made a cathead with some rigging straps to a rafter and the wall, some heat and some hammering got it off. now that im learning more about the delicacies of a lathe, may have not been the best approach but it did come off. when i got it apart didn't seem to have damaged the bearings any. i actually had it suspended so the blow didn't drive home through the machine. and when i went back together it dialed in fine so fare as i can tell!