Help part needed

[Don PhillipsParticipant @donphillips14362]

Hi I need to find someone who could make me an adaptor for my lathe cuck

the spindle on the lathe is 3/4 16 tpi my chuck is 1inch 10tpi I need an adaptor To make it Fit

any help would be welcome

thanks Don

[Don PhillipsParticipant @donphillips14362]

Chuck adaptor

[Martin ConnellyParticipant @martinconnelly55370]

Not a very big wall thickness and different pitches. That would possibly require an extension as a result so probably not a good way to go. Has the chuck got a removable back plate?

Martin C

[David George 1Participant @davidgeorge1]

Hi Don some pictures would help and make and model also.

David

[Mike PooleParticipant @mikepoole82104]

If the chuck has a separate backplate then making a new one for the required fitting may be the best plan.

Mike

[Howard LewisParticipant @howardlewis46836]

+1 for Mike's comment about the wall thickness, and making a new backplate..

A 16 tpi Whit form thread is going to be 0.040" deep, so the minimum wall thickness will only be 0.085", which may just about suffice.

Although being of the "brick mausoleum" persuasion, I would prefer more.

Being nosey; what lathe is it, please?

Howard

[duncan webster 1Participant @duncanwebster1]

Bore out the existing thread, loctite a bush in and screwcut that?

It's not going to be easy unless you have a second lathe

[Don PhillipsParticipant @donphillips14362]

Hi the chuck dosnt have a back plate the thread size on the spindle is 3/4 unf and the chuck is 1" BSF I have an adaptor for my indexing chuck but that in 3/4 unf to 1" unc that is 8 tpi and the other is 10 tpi I have tried to buy adaptor for it but BSF is not in fashion now so stuck

[egaParticipant @ega]

Posted by duncan webster on 20/03/2020 16:47:47:

Bore out the existing thread, loctite a bush in and screwcut that?

It's not going to be easy unless you have a second lathe

If the dimensions of the spindle nose were known, a dummy spindle nose could be turned and a pre-prepared threaded blank screwed on which, in turn could be screwcut to fit the chuck.

I agree that a second lathe is probably needed but it would help to have fuller information about the OP's lathe, its capabilities and location.

Has anything been said about a register on the spindle?

Edited By ega on 21/03/2020 14:34:06

[Howard LewisParticipant @howardlewis46836]

1" BSF thread is 10 tpi with a depth of 0.064" so the core diameter is 0.872" which differs from 0.750 (3/4 UNF) by 0.122, leaving a minimum wall of only 0.061"

Which is not much metal to transmit the torque when you are cutting hard.

I see little alternative but to follow Duncan's advice:

Bore out the chuck and press / Loctite/ Screw and Loctite in a larger bush, to provide more material outside the 3/4 UNF thread, when you cut it and the register.

The bush would need to be 1 " diameter, if plain, or 1.250" if threaded, to make me happy.

But I favour brick mausolems!

Howard

[Don PhillipsParticipant @donphillips14362]

Hi

I am aware that the adapt or will have to be one that will stand out from the original spindle as the 3/4 unf thread need to be 30 MM. deep then a 1 " bsp thread 30 MM. long will need cutting and it will be about 65 MM. total length this is not a problem as I already have a similar adaptor for my indexing chuck that is a different thread to the one I need making I was just hoping someone would be able to make one for me preferably near Nottingham

thanks Don

[not done it yetParticipant @notdoneityet]

I would think the adaptor needs to be fitted to the chuck and then the register for the lathe cut while mounted – or the run-out could be horrendous for a little lathe, particularly with that sort of overhang from the support bearing.

[David George 1Participant @davidgeorge1]

Hi Don I would love to help and live not to far away Sutton in Ashfield nr junction 28 M1. But as things are at the moment I am self isolating as me and my wife have had a virus but don't know if it was coronavirus or something else but the doctor has said we should keep away from others at the moment. Will send you a personal message look at the top of the web page little envelope when logged in.

David

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