Remove Seized on chuck ??

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awemawson:
I cannot quote chapter and verse, but I distinctly remember John Stevenson on another forum asserting that the thread AND the register hold the chuck concentric, as even a loosely fitting thread, when under tension, settles on the pitch circle of male and female forcing concentrically. John is an engineer who's views I respect, and he has a huge wealth of practical experience.

lordedmond:
My take on what happened on further inspection of the pics is

That a small piece of the casting in the thread region broke loose and jammed up the thread thus causing a cam like lock or one way clutch so to speak

Parting part way through relieved the tension just enough to move the backplate thus relieving the cam lock

IMHO I cannot see the parallel register had any part to play In the jamming/locking of the back plate

As for the JB Weld repair yes it's good stuff I do use it but the parts do need to be clean and oil free it would be one hell of a job to ensure that was the case this case , a good soak in trike followed by a ultrasonic clean but the can you be 100%sure. It's a none starter for this application

Stuart

PekkaNF:

--- Quote from: awemawson on June 09, 2014, 03:50:44 AM ---I cannot quote chapter and verse, but I distinctly remember John Stevenson on another forum asserting that the thread AND the register hold the chuck concentric, as even a loosely fitting thread, when under tension, settles on the pitch circle of male and female forcing concentrically. John is an engineer who's views I respect, and he has a huge wealth of practical experience.

--- End quote ---

I agree about John Stevenson, he pretty much knows what he is talking about.

I just see here two surfaces that (radial and axial) register back plate, I assume that the tread is dimenssioned not to interfere with rest of the register. I could be easily wrong, there could be an additional aspect here I'm not aware. I have been reading myford register/gauge plug turning material and some steps are not very clear to me - I have been assuming that the great care used to spend on making thread was to ensure that the thread pulls backplate squarely to spindle nose I.E. not to offset it anyways.

Pekka

Manxmodder:

--- Quote from: awemawson on June 09, 2014, 03:50:44 AM ---I cannot quote chapter and verse, but I distinctly remember John Stevenson on another forum asserting that the thread AND the register hold the chuck concentric, as even a loosely fitting thread, when under tension, settles on the pitch circle of male and female forcing concentrically. John is an engineer who's views I respect, and he has a huge wealth of practical experience.

--- End quote ---
Andrew, your thinking is correct about the threads self centering axially about the PCD when tension is applied through tightening.......OZ.

micktoon:
Hi Lads, well this topic has certainly got some banter going anyway :thumbup: I am not going to re use this backplate just from common sense point of view really , I might have been lucky not to have damaged the spindle threads and might not be so lucky next time, if this did happen I would be kicking myself :palm:. If it was the last one in the world and you had to make a part for the boat to be able to escape the desert island you were trapped on I dare say it could be repaired with JB or what ever and it might also be fine for further use....................BUT I know my luck and do not want to increase my chances of hassle lol.
So I will try to get a backplate , If I can not find one I will have to make one, I have my four jaw chuck to use the lathe anyway. As for the threads and the register, I had thought the register was what held the cuck in the correct position as it was screwed on and the threads in effect were only keeping the chuck on the register and not in themselves actually putting the chuck into position.

Cheers Mick

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