# Thread adapter (1 1/8-10) for spindle



## KennyC (Dec 5, 2017)

Hello, have a couple other posts going on the site regarding my restoration of an early 1900's lathe. I have struck out on finding any adapter for the 1 1/8-10 spindle thread. I'm now looking into modding a different back plate to fit my chuck.

I most likely still go that route but wanted to see if anyone would be interested in making an adapter for me. The reason being is in case I ever want to swap out that chuck to something more modern I could. Maybe go from 1 1/8-10 to 1" -10tpi or another common size?

The way it's setup now:

The lathe spindle is 1 1/8" x 10tpi. It has a bronze thread adapter to fit a Union 4" chuck. The chuck back plate is threaded at 1 5/8" 10. The spindle threads are good. The bronze adapter threads are worn causing a bad wobble at the chuck.


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## JerryK (Dec 5, 2017)

I would be glad to help you out with this,
I need a sketch and the material.
A mating part for the thread is also best.
Just take care of shipping.
It’s only a hobby


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## Dave Paine (Dec 5, 2017)

I may be able to help you.  I live in NW Lehigh county, at the top of Rt 100.

I have pieces of aluminium round stock of large enough diameter.   I am not sure if I have a piece of round steel large enough diameter.

The biggest issue is a male thread for the test fit.   It sounds like the existing adapter would not be good to use for a test fit.


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## KennyC (Dec 5, 2017)

Thanks guys for the quick response... Very cool and very helpful! This  I will look for material and some test threads and get back.

If you didn't see the restoration post here is a picture of the lathe when I first got it.


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## dayzman (Mar 10, 2018)

Hello,
I wonder if I can tag along with this thread. Only difference being, I am seeking a 1 1/8" x 8 to 1" x 8
I bought myself an old Powermatic 90. It is a heavy wonderful machine, (about 1965 vintage) but I can not find an adaptor from the outward bound spindle which is one and one eighth inches. (8 threads per inch). My chucks from the shopsmith are all one inch (8 threads per inch). The inward bound is one and one half inch. Bigger than I am used to for sure. But I do have adaptors for that over the bed.
Can I impose on someone to make me an adaptor as well? I purchased this lathe to do large diameter things, and the faceplate will work, but I also need to attach to the chucks for the finishing work.
Thanks in advance, and if someone can advise on a good place to purchase the raw metal, I would be most appreciative as well. If the someone who may be interested in assisting me, could advise me exactly what I will need to the raw material. (diameter and length). 
Of course I am willing to pay for materials (plus any shipping costs) and also willing to pay for the time involved.
Thanks in advance.
My first post here, so I hope it is within parameters.
Charles (dayzman)


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## Dave Paine (Mar 10, 2018)

The challenge for anyone doing this is a test plug.   It is normal to use a male plug of the designated thread to test the fit when making the female thread.

Is the thread Left Hand or Right Hand.   I would expect outward thread to be Left Hand.

Do you have anything which fits the outward end of the spindle?


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## dayzman (Mar 10, 2018)

Thank you.
Yes I do have two faceplates that fit it, but one is 12 inch and the other is 8 inch I think. You are correct, it is left hand thread. But being that odd thread, 1 1/8 size is strange. Even Powermatic does not have anything suitable. Their thought is, hey, that is for large stuff. I agree, but I like to finish things with a chuck. Having said that, perhaps it is me that is out to lunch here. Perhaps I need to finish the large things with the faceplate. That is not the norm for me. But I have not turned anything larger that 16 inch. I am looking to do some 24 - 36 inch things.
Thanks for the response.
I do have a small male thread that fits the chucks that came with them. Would that help?
Charles


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## Dave Paine (Mar 10, 2018)

How about a picture of the small male thread item next to the outboard thread of the spindle.


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## dayzman (Mar 10, 2018)

Hope this works..


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## Dave Paine (Mar 11, 2018)

The picture helps.  The spindle outboard is left hand thread.   The shorter piece looks to be right hand thread.   Not easy to confirm via the picture but you will be able to tell.

The problem is that I expect your Shopsmith chucks to be right hand thread.  They would come off the adapter when the lathe is rotating.

You are better off using the inboard end of the spindle and removing the inboard chuck or faceplate.

Is the inboard end the same 1 1/8in x 8 tpi?


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## cathead (Mar 11, 2018)

Give some consideration to making a chuck mount plate that uses the 1.125 x 10 threads.  You will have
better accuracy without an adapter.


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## dayzman (Mar 11, 2018)

The inboard spindle is 1 1/2 inch.
I was thinking today, for the outboard spindle... it is 1 1/8 inch. The inboard spindle is 1 1/2 inch. So I have chucks that fit the 1 1/2. So if I could get an adaptor from 1 1/8 to 1 1/2 I would be all set. In the pic there is a collar with set screws, that is two inch with the thread 1 1/8 8tpi.   So a collar two inches long, with inside 1 1/8 (8tpi) LHT, and outside 1 1/2 (8tpi) RHT, with 2 setscrews would fix me up.
Make sense?
Thanks, Charles


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