Chuck Adaptors

[Martin CargillParticipant @martincargill50290]

A friend has some M33 threaded chucks and wants to fit them onto different lathes with 1 1/2″ 8 tpi and 1 1/2″ 6 tpi threads. Has anyone seen adaptors that can handle these threads? Ebay seems to have a number of them but none that suit these threads.

 

Martin

[DC31kParticipant @dc31k]

Am I missing something here?

1 1/2″ is 38.1mm, which when I studied maths, is further along the number line than 33mm.

FWIW M33 is more used in the woodworking world.

Axminster, Charnwood Tools, Rutlands, RDG and Chronos all have M33 to smaller adaptors.

[Mike HurleyParticipant @mikehurley60381]

As DC31k says, M33 is a common thread on wood lathes. Do we assume he/she has some woodworking chucks , if so it would be useful to know what type of lathes they are destined for as the threads stated seem unusual.

If you can get some more details, someone may be able to suggest the advisability of these ideas, or offer other ideas.

Regards, Mike

 

 

[Martin CargillParticipant @martincargill50290]

Yes these are woodworking the M33 is a modern wood lathe, the imperial threads are a Union Graduate and a Viceroy tds 6. The adaptors will not be a simple bush type (as has been pointed out 33 mm is smaller than 1 1/2″) but will have to be a longer adaptor with the relevant threads at each end. I know they could be made but I was wondering if anyone knows if they are available commercially.

 

Thanks

Martin

[Ian ParkinParticipant @ianparkin39383]

I make lots of chuck adapters and can confirm that they are not made in quantity commercially

this is the style that i make 

[Ian ParkinParticipant @ianparkin39383]

That particular one is for a wadkin RU which is 2” 4.5 tpi and it has a m33 x 3.5mm male thread and it weighs 2.5kg

[VicParticipant @vic]

Most adapters for wood lathes move the chuck quite a way from the headstock bearings do not such a good idea. One guy on one of the woodturning sites had a new spindle made with an M33 thread for his old lathe.

[Howard LewisParticipant @howardlewis46836]

A 6 tpi Whitworth form thread has a depth of 0.1087, so will be too deep to be cut immediately above a 33 mm thread.

So the adaptors will have to be such that the 1 1/2 x 8, and 1 1/2 x 6 external threads have to be cut outboard of the internal M33 thread.

Possible, but the downsides are

1) Increased overhung loads imposed on the Headstock Bearings.

2) Decreased centre distance

How damaging are these features you have to decide.

In most cases, with commion sense, neither should be a job stopper.

Howard

[Howard Lewis]

On Howard Lewis Said:

So the adaptors will have to be such that the 1 1/2 x 8, and 1 1/2 x 6 external threads…

The lathe on which he wishes to fit the adaptor already has a very nice 1 1/2″ – 8 external thread on its spindle nose. How will a duplicate of the spindle nose thread assist him?

Just to be clear, the female thread in the chuck he has is SMALLER than the male spindle nose thread on the machine on which it is proposed to mount the chuck.

[Nigel Graham 2Participant @nigelgraham2]

Actually he specifies two lathes, with different thread pitches!

For reasons clear in replies above, if this was my equipment I would prefer to change the backplates, though it may mean needing two sets of chucks.

[Martin CargillParticipant @martincargill50290]

Thank you for all of your replies.

The reason for wanting to mount different chucks is to have the ability to swap between jobs, without having to take the jobs out of the chucks. I have looked at the M33 chucks (with a view to swapping backplates) but they do not have a backplate – the thread is an “integral” part of the chuck. Nor is there any space to drill through the chuck to attach one and I’m sure that I would not be popular if I drilled and inserted three bolts through the chucks scroll!!

He did find one seller who was advertising relevant adaptors but when he enquired the found that they had been discontinued.

 

Martin

 

 

[Ian ParkinParticipant @ianparkin39383]

Martin

as i said earlier there seems to be no -one making 1 1/2″ adapters commercially

they did used to be available….apparently they had a lot of returns as the registers vary slightly between machines that take those theads so it was difficult to keep stocks of good adapters

 

[JohnFParticipant @johnf59703]

Robert Sorby do both of the adaptors see  — https://robert-sorby.co.uk/product/chuck-exerts/

John

edit — Assuming the metric thread is the M33 x 3.5 !  standard WW thread

[peak4Participant @peak4]

I pointed someone on a different group to Turners Retreat for something similar, though they were after inserts to a smaller nose thread.
As implied by John above, Sorby call this style to a larger thread Exerts, rather than Inserts.
It’s tricky when the search term isn’t obvious.

Unfortunately, it seems that the only have one of the required styles in stock, which might tally with Ian’s comment

See Here

Bill

[Ian ParkinParticipant @ianparkin39383]

The sorby ones are excerts as you say but they only screw into the patriot chuck which is 38mm x 3mm AFAIR

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