Very Stuck Chuck on 17" round head

[lindse34]

I had a shaft with eccentric lobes that I needed to polish after making a press on bushing for it. So I thought it would be a great opportunity to try using the 4 jaw to mount the shaft eccentrically so the lobe would be centered. So the first step was to remove the 3 Jaw. After reading about the somewhat weak low speed gears in these machines I figured I'd make a spindle clamp so no back gears were involved. I made it so it would fit on the rear of the spindle without removing the drive pulley and guard. After attaching the clamp and shoving a stand under it to hold it I proceeded to chuck a 1 inch grade 8 bolt and commenced hanging off the wrench handle. After about 2 minutes of that and adding the obligatory cheater bar (a 2" wrench hooked on the end), the clamp I made started slipping so I grabbed a F clamp to help the 3/4 " bolt that was doing all the clamping before. I could now hang off it but it would still slip a little. This was Friday night so I said enough, sprayed the spindle with penetrating oil and had a beer.



Saturday I got an assistant and after considering our options I grabbed a failed 3" wheel spindle from a farm implement and welded a 2.25" nut on the end of it. I milled 3 flat lands on it for the 3 jaw to grab. We then proceeded to put a 1 inch impact on the 2.25" nut and a 60" pipe wrench on the chucked wheel spindle. We reasoned the combined continuous torque of the pipe wrench and shock of the impact would do the job. After 15 minutes of that we decided heat was needed. Fearing for the spindle seal I was a bit leery of too much heat from the torch but we did it anyway. After 3 cycles heating, impacting and cooling the chuck was still firmly in place. Our limiting factor seemed to be the clamp on the rear of the spindle.



Today I started making a full length clamp for the back side of the spindle so I can get at least 2.4 inches of clamping area. I am thinking I can get 3 3/4" fine thread bolts on it for some ridiculous clamping power. Then I think I am going to remove the 3 jaw from the back plate and make a mating plate on a rotary table. I think we have already put the 3 jaw through too much abuse. I plan to weld very heavy stock of about 12" in length from the center line so we can strike it and a 3 inch square tube that is about 4 feet long for leverage.

Is there anything else we should be doing to improve our chances? One thing that does concern me is if we use a hammer to hit any lever it will place force on the spindle bearing whereas the air impact does not place a downward force on the bearing. This seems like inviting brinneling of the spindle bearing. I might just weld a 2.25" nut on the mating plate so we can still use the air impact.

If this doesn't work I am just going to cut the backing plate off the spindle and remount the 3 jaw on a new one. I am starting to think this chuck has been on this lathe since the 70's.

And I polished the shaft with the 3 jaw anyway so I don't know why I am still pursuing this..... :nuts:

Thanks and Regards,

Matt

 

[12bolts]

...sprayed the spindle with penetrating oil and had a beer.

More oil and more beer. Much much more beer. Got to make sure the oil has time to penetrate :drink2:
Seriously though. What sort of penetrating oil are u using?

Fearing for the spindle seal I was a bit leery of too much heat from the torch but we did it anyway

I am guessing the assistant was the proponent here:thinking: Sorry not much more to suggest than more penetrant and more beer, (oops sorry),,, time for it to work.
Rapid heating is the secret. Big torch. Dont allow too much heat to transfer to the spindle, otherwise expansion here eliminates the advantages gained by heating and expanding the backing plate..............or melting the seals.

Cheers Phil

 

[swatson144]

I always use a big piece of hex in a 3jaw. Pressure like you are applying and a few shocking raps while it is loaded. The big piece of hex keeps the jaws mostly in their slots and does not slip and ensures the wrench a good grip.

I had to use a wrench and cheater 200 lbs of me hanging off of it and a friend whack the wrench with a hammer. It popped loose on the 2nd whack with no harm. Bouncing up and down on the cheater just makes the clamp slip bit the hammer shock helps and doesn't put much impact on the bearings.

Steve

 

[Ray C]

I feel your pain and had a similar situation after doing a bunch of interrupted cutting. Every tiny impact on the piece was tightening the chuck. Anyhow, the solution was relatively easy. I removed the jaws, put a bar through the slots and put a cheater over the bar. I rigged-up the tailstock ram to hold a plate against the face of the chuck to keep the pipe in place. I held a good deal of tension on the bar and a friend whacked the pipe closer to the chuck a few times with a 3lb persuader and bingo. Gotta be careful of course, when it breaks loose, the guy holding tension takes a spill. It will come off so hold off on doing anything drastic. Good luck.

EDIT: Oh, in your case, you have a 3 jaw so a pipe wont go all the way through the jaw slots but still, I think you can get some mileage out of that technique.

 

[swatson144]

If all this doesn't get it then the last try before cutting the back plate off would be to warm the chuck all through until the spindle starts to warm from contact and then pack the spindle with dry ice if it's available or even bags of regular ice. The spindle is so little mass compared to the chuck that the only way to get a temperature difference would be heat both and cool the spindle.

Even heated and cooled expect to have to shock it.

Steve

 

[Ray C]

One other thing... You want to apply torque as far on radius of the chuck as possible instead of clamping a smaller diameter piece in the jaws and trying to spin that (although that works fine for a mildly stubborn situation). Imagine for one minute if you could, clamping a 20" diameter disk in the jaws then, applying the torque from a bar to edge of the 20" disk. There are actually 2 torque forces at play in that case and the total torque is the product of the two.

Anyhow, by putting a bar in the jaw slot, you're effectively creating the torque of the "imaginary" disk mentioned above -but it's a really big disk. If you put an L-shaped piece on the end of the bar you're pusing on and pull on it (instead of pushing down on a straight bar) then, you have the two torques mentioned above working for you. First start with the straight bar and cheater then if necessary, put perpendicual bar on the end of the cheater.

Hope that made sense and that you're not :rofl: at me.

Hang in there, I know exactly how frustrating this is...

EDIT: Don't slap me here but, are you sure that's a spin-on chuck? -And is that beast unplugged while you're doing all this?

 

[ranch23]

EDIT: Don't slap me here but, are you sure that's a spin-on chuck? -And is that beast unplugged while you're doing all this?

How goes the battle?

 

[lindse34]

So today I was leafing through the manual for these lathes that is posted on this site and noticed the 17 inch is supposed to have a L0 long taper key drive. After questioning my memory for about 5 minutes I went to the shop expecting a heaping of humble pie coming my way, but I'm pretty sure its a threaded spindle. I had made this conclusion before based on the 4 jaw that came with it but then I realized maybe it was just thrown in the deal and not actually for this lathe. At any rate I took some pics of the spindle and ironically the threads in one spot were chipped enough to look like a key way but after cleaning it it's just a chipped thread. Which may point to other problems.... Actually I kinda wish it was L0 that would probably be a lot easier. From what I measured I think it is 2-3/4"-8 thread. So I don't know if they sometimes came with that instead of L0. This is the lighter duty version of this lathe so maybe that has something to do with it.



So Ray, for a bit I was thinking your question about spindle type was very relevant.

Also we unplugged it when we made attempts 1-5 on this thing. I assume your concern is inadvertently turning it on? I was wondering if you had another scenario of concern that didn't involve hitting the switch and bad news ensuing.

Allegedly the 1 inch impact is rated a bit north of 1600 ft lbs but with the additional mass of the chuck what is actually being felt by the threads would be considerably less. I'm not sure I follow your scenario correctly.
"If you put an L-shaped piece on the end of the bar you're pushing on and pull on it (instead of pushing down on a straight bar) then, you have the two torques mentioned above working for you. First start with the straight bar and cheater then if necessary, put perpendicular bar on the end of the cheater."
Wouldn't the second perpendicular bar on the end of the cheater bar apply a torque that is then perpendicular to the spindle axis of rotation? Maybe I am not visualizing it correctly.

Steve,
When I was heating it up Saturday we joked about getting liquid nitrogen to pour in the spindle. It's not terribly hard to get if you know someone that stores livestock semen as people do in the Midwest. Dry ice with maybe some oil to increase the heat conduction seems more practical and we won't have to make a million semen jokes.

Phil,

I was using PB Blaster. I prefer Break Away, but PB was handy. I did see somewhere online someone was touting the merits of Kroil in this situation so I may have to get some. May be good for various other things we deal with that have been welded by time.

Anyway I bored the center of clamp-to-be tonight and hopefully Mcmaster Carr shows up tomorrow with some 12point 5/8" bolts and grade 8 nuts. It would be a good Thanksgiving present to get this off.



Thanks for all the input,

Matt

 

[12bolts]

Matt,
Something else I remember reading for a stuck chuck was hanging a very heavy weight on a lever from the chuck and leaving it overnight.

Cheers Phil

 

[Ray C]

Hopefully at noontime or this evening, I'll have time to draw-up a sketch of the L-shaped bar. Stand by for that. Also, the concern about unplugging it was purely a matter of safety. Sorry. Didn't mean to offend but but if a buddy accidentally hit a power switch with a bar perpendicular in the chuck... That could be bad...