Remove Seized on chuck ??

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micktoon:
Hi Oz , thanks for that I have ordered them as think I will have trouble setting correctly without them.

This is the story of how the chuck was removed

I already had a boring bar I had made and a quick change tool holder that would hold it. The basic plan was to drill the end of this boring bar and make a parting tool incert to fit in the end of it that would align with the very rear edge of the backplate just short of where it mated with the spindle shoulder.

Thes shots of making the bar are in my mate Daves workshop, using hid Kerry AG lathe and Emco FB2 mill, cheers again Dave.
Centre drilling the bar

Drilling the bar for the incert to fit

The incert test fitted in the bar, this was something Dave had lying around so just needed altering as it was already roughly what we needed.

The side of the bar needed milled of for clearance and the other side was milled flat, drilled , tapped M6 and grub screws used to lock the incert in place

This is the new tool in the holder lined up for action

Note the DTI this was to gauge how far the tool advanced to make sure it did not mark the spindle

So far so good , just going slowly, once it was only a fracion to go, I tried putting bolts back through the backplate and the slightest of taps loosened the B*****d

This is the backplate after its surgery, just as planned , the spindle not touched but the stress locking the thread releaved so free

The spindle survived the ordeal

This it the blow hole in the casting that has been threaded, soon as I saw this I remembered it was like this before, it was like this when the chuck came with the lathe and has been used many times, do people think this is what will have caused the problem and is it savable by filling with metal putty and reshaping or bin it ? bearing in mind its either hassle or expensive to get a six inch backplate.

So at least someone else will be able to use this method to remove a locked on chuck without damage .........the back plate has enough 'meat' to be used again if its repairable too.

Cheers Mick

vtsteam:

--- Quote ---do people think this is what will have caused the problem and is it savable by filling with metal putty and reshaping or bin it ? bearing in mind its either hassle or expensive to get a six inch backplate.
--- End quote ---

I think either a piece split off in that area or a piece of swarf got caught unnoticed in the cavity there.

I'd probably fill it with JB Weld metal filled epoxy and re-cut the thread, but that's just my nature, salvaging old metal if at all possible. Not necessarily good practice!

Also a great fan of the qualities of JB Weld in relation to cast iron

But it seems to me, if there are no holes for swarf to collect, and the thread is again smooth it is unlikely to happen again.

And now with a special tool to free it..........

lordedmond:
Mick

I would bin it ,buts that's me

There's a nasty crack to the left of the main cavity a couple of threads further out.

How many more threads are cracked ,looks like it has a lot of inclusions and stress fractures

But that is bases on what I see ,what does the mark one eye ball say , a good dig round with a brass probe may show up any more

It would be a right old pain in the rear if it happens again

Stuart

awemawson:
I'm in the 'bin it' camp. Life's too short for this sort of thing to be repeated. Buy a steel backplate blank to avoid future issues.

Fergus OMore:
In my earlier 'Number4' in this saga, I referred to two different threads on my Myford bit. I think that it was a Dividing head spindle- but no matter. Two issues arise- not one.

There is the question of the register which has not been addressed. The threads on the chuck are academic and secondary . All that the threads do is hold the chuck onto the spindle. For what it is worth, you could file off the tops of the crests- so long as the chuck holds its register- and doesn't rotate off.

Sorry folks, but I did all this malarkey many years ago on an old ex-wartime Pools Major which probably none have heard about.

Regards

Norman

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