Chuck stuck on spindle....Help

[Micktoon]

Hi all , I am hoping that someone can help with a problem of a chuck that is stuck on my lathe spindle. I am on the finishing jobs of my rebuilt Harrison L5 and had screwed the chuck on with very light hand pressure only after cleaning both spindle and chuck then applying light oil. I have not even turned anything in the lathe but when I have come to remove the chuck its stuck fast. Proper stuck fast too.
So far I have tried .
large hex bar in the chuck and big spanner on it, tapping the spanner to shock it and jerking spanner with the gear train locked so the spindle can not rotate.
The usual realeasing oils etc, left over night and also repeated after heat applied
Removing the chuck from the backplate , incerting 3 bolts through backplate holes and levering with 3 feet long 1 inch bar , hitting said bar to shock
Heating the backplate up with propane torch and trying to shift while hot , then when cooled again, tapping all around trying to break seal
Replacing chuck and chucking large hex bar then trying to loosen with large socket and windy gun. ( only thought of this after the other attempts )

The force used so far and the hits have gradually reached the point where something is likely to break if any more force used so looking for ideas. It would seem totally impossible that it has become stuck this tight. I know 100% the threads are clean, there is film of light oil and the chuck has not been tightened other than by light hand pressure. I am assuming the rear face is seated against the spindle shoulder and the 'lock' is between this and the threads, will this be the case ? I think it must be as this chuck has been on and off many times before and I know the register is clean and oiled as are the threads.

Here are some photos of what I am dealing with.

This is a samller bore Harrison spindle of the exact same design showing the thread, register and shoulder, then the chrome cover, note the shoulder sticks out the chrome cover a small amount. The actual one on the lathe is clean and spottless and oiled.


This is the same design backplate that is stuck on my spindle, showing the register and rear face that is butted tight to the shoulder on the spindle.


This is the stuck backplate with the bolts through it , that the large bar was acting against both jerking and hitting with the gear train locked stopping the spindle rotating, I have gone to maximum force with this , it would have shifted a truck wheel nut in my opinion.


This is a shot to show the spindle shoulder just visible coming out the chrome cover, the backplate is mated up to this. I have a parting tool in the tool holder to show roughly what a plan might be ?


The red small tube is pointing to the spot that I could with a slim parting tool slice into the backplate just shy of where it mates to the spindle shoulder and releave the tension or compression causing the locking.


So really what do peolle think is causing the thing to be seized, what I think some sort of hydraulic type lock or taper type lock between the backplate mating to the spindle shoulder or could it be the threads ? they are clean and oiled. I would really like to svae tha backplate as a hard job to find them for decent price and do not want to have to make another one, I do not want to damage the lathe in any way.
All Myself and a friend can come up with is to maybe drill very small holes in the backplate so releasing fluid could be directly introduced into the threaded area ( if that is what the problem will be) Or to make a special parting tool so it could part away the very end section of the backplate nearest to the spindle shoulder yet miss the spindle by a thou or two, I could also make the tool so it could not go in too deep and mark the spindle as I have a smaller spare backplate with the exact same register to measure.

Any help most appreciated

Cheers Mick

[Highpower]

(06-04-2014, 10:08 AM)Micktoon Wrote: ..... Or to make a special parting tool so it could part away the very end section of the backplate nearest to the spindle shoulder yet miss the spindle by a thou or two, I could also make the tool so it could not go in too deep and mark the spindle as I have a smaller spare backplate with the exact same register to measure.

Any help most appreciated

Cheers Mick

Mick, I'm afraid I have no unearthly idea why your chuck would become so stuck like that. I can say that I've used a parting tool in that way to remove rifle barrels that were over-torqued onto their receivers. They let loose with a bang sometimes when the tool breaks through, and then the barrel can almost be unscrewed by hand. I agree with you and would consider that a last resort however.

Just thinking out loud here..... But what if you tried chucking up a good size piece of steel bar in the lathe, and tried bump knurling it at slow speed with the spindle running in reverse? Maybe the side pressure on the chuck/backing plate combined with the reversed rotation might coax it to come loose? Just an (amateur) thought.

That is one beautiful looking lathe by the way! Best of luck to you.

[DaveH]

Mick,
Can't think of anything at the moment - just be careful hitting it you don't damage the gears.
Seems strange for it to be suck so fast after such a short time

DaveH

[krv3000]

hi just a thort did you set the lathe a way with the chuck on ? if you did the chuck has locked it self on as the chuck was not tightened on to the spindle when you set the lathe ruining the lag between the spindle rotating and the chuck being stationery will force the chuck to tighten More than it shod 1 way to try and get it off mack up a plate say off 13mm plate with the same pcd spacing for the chuck fixing screws welled a long Peace of box or pipe to the plate and with the aide of a Friend while sum one is applying leverage on the pipe to undo the back plate sum one hits the fixing plate with a big hammer this shod have the effect of a impact gun that you wood use to undo stubborn bolts

[Hopefuldave]

Tricky... I'd be worried about taking teeth off the gears, have you tried unlocking the spindle, hex bar in the chuck, ring or other sturdy well-fitted spanner and a Really Big Hammer Swung Fast? Alternative to RBH, apply air hammer / SDS drill to the ring spanner to see whether repeated shocks will unstick it?

[Micktoon]

Hi Lads thanks for the ideas so far. I have had a large air impact gun onto the end of a bit of say 30mm hex bar in the chuck with the socket bottomed out on the hex bar and kept repeating say 30 secs of impacting then tried again ...and again .........and again, it was really vibrating through the whole area and also pressing onto it at the same time, still totally solid.
Bob the chuck was definatly screwed right up but only with hand pressure, they were both the same temp too.
I am glad to hear about the rifle barrels as at least the princable should work.
Another suggestion on Madmodders has been to make a taper gadget that would fit into the rear end of the spindle tube then expand by way of a bolt type set up , then have a long lever on this to stop the spindle rotating, so it would be , in effect then just be a tube with a lever on the rear end and a backplate threaded on the other so any forces involved with trying to remove it would not involve the gears. Seems like a good idea but to be honest with the force I have had on it up to now I can not see a taper wedge type gadget not rotating in the spindle.
The other thing is why has it happened and how do I stop it happening again ?
As a note the much larger chuck on my Binns and Berry lathe of the same design that has not been took off for maybe 10 years, with a bit hex and a 12 inch spanner and only hand jerk came loose no bother ......... its a funny old world eh .

Cheers Mick

[DaveH]

Mick,
I've seen with stainless where the nut gets stuck on - we would have to cut the nut off and re-die the thread - just spinning the nut on by hand
In the past talcum powder was used, I'm sure there is a modern product.

Sometimes in the main lathe spindle there is a hole I don't suppose there is a hole in yours.
It is also best not to have any thing against the gear box casting - I've seen them broken.

DaveH

[Mayhem]

When I got my lathe the 4-jaw backing plate was stuck on and I had a similar problem to you. I removed the chuck and made a "wrench" as shown below.

   

I had a friend lock the bull gear with a "too" ground to fit the gear teeth and hold it from moving. I then grabbed the end of the wrench and lifted my feet off the ground, so that all my weight was on the wrench. I had to bounce around a bit but eventually it cam unstuck.

Good luck!

[Sunset Machine]

I've only had one stuck like that. What ended up working for me was to lock a long bar (3-4 feet) sideways in the chuck jaws and hang a bucket of junk from the end. Next morning the bucket was on the ground, the chuck came loose. Voodoo magic, dunno. Someone before me had beat on it good and broke some gear teeth, chuck handle was hammered. Bubba had gotten to it. The lathe was next to a dumpster when I found it.

John Oder on Practical Machinist showed how he made a large wrench for the outboard end and one for the chuck, squeezed like scissors to get it off. Plumbers will use a similar technique with pipe wrenches to get stuck fittings loose.

How your chuck got stuck is a mystery. Is the rear face perfectly square to the threads? Perhaps a little cockeyed and it wedged tight? Still a puzzle though. A jokester with some loctite?

Nice looking lathe. Wipe your tears away and keep at it. How frustrating. Might have to turn the backplate into chips, but I'd be keen on finding out why it got stuck...

[Micktoon]

Hi lads, thanks for theadvice and support, I am glad to report ..............

The Ba##### is off after my mate Dave and myself had more tries we have then made a special parting tool and went with the plan of parting a slit in the back plate just a fraction where it mates with the shoulder of the spindle. The reason being it might work and the back plate might be able to be used again as enough metal there or if not it would be easier to turn it off in the threaded area with this tool rather than turning the whole six inch plate away.
Photos will follow but once almost through but before risking hitting the spindle , it came off with hand pressure on an adjustable spanner.
What I found ( and had seen befoe once I saw it to remind myself ) was a fault in the threads of the backplate, its got a blow whole in the casting and the threads run through this fault leaving sharp edges that must be the cause I presume.
Anyway its off and the spindle is ok so I just need to make or find a backplate now but have the four jaw chuck until then.
For anyone else with the same problem as I think it was Pete W said with the rifle barrels this method does work so well worth noting .

Cheers Mick