South Bend 9 problem

Hi Folks,
I recently got a South Bend 9A lathe. It is a decent old machine with one issue and I thought if anyone here has a 9 perhaps they could help.
On the cross slide behind the handle is the dial with the 0.001" graduations. The dial should have a thumb screw so you can reset to 0. My thumb screw is missing. I tried to turn a 12x32 screw in the hole and the diameter seems to be correct but I can only turn in 1 turn so the thread is not 32tpi. I tried to figure out the tpi with a thread gage and I think it is 30 but it is hard to tell.
So if anyone has an SB 9 and you felt inclined could you get the tpi on the thumb screw for me?
I would definitely appreaciate the help.
Izzy

Haven't use South Bend lathes but Gisholts had sliding markers on the dial to set 0 anywhere. I think the set screw is just to hold the position as you turn.

I don't have a South Bend. If the #12 is the right diameter the only other standard threads I know of are 24 and 28 tpi, maybe try those. You might get a quick answer from machinist/teacher TubalCain who probably can check one of his lathes. http://www.mrpete222.com/ I wrote to him about something and he answered right away.

JKJ

Can you measure the ID of the threaded hole?
Does the compound dial use the same lock screw?

Hay thanks for all the responses. Now for the questions to me.

Yes the thumb screw locks he dial so it cannot move as you are using the lathe which of course is very important.
I had tried both course and fine thread #12 screws. It was my mistake above where I said 12x32. It must have been 12x28.
Ya I can measure the id of the hole. I had done that at one point and checked my Machinery Handbook and found the id is correct for a #12 screw.

I will try and contact Tubal.

Quote:

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Originally Posted by Izzy Camire

Hay thanks for all the responses. Now for the questions to me.

Yes the thumb screw locks he dial so it cannot move as you are using the lathe which of course is very important.
I had tried both course and fine thread #12 screws. It was my mistake above where I said 12x32. It must have been 12x28.
Ya I can measure the id of the hole. I had done that at one point and checked my Machinery Handbook and found the id is correct for a #12 screw.

I will try and contact Tubal.

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Head down to hardware store and spend say $3 or so and get one of each. Lots faster than trying to contact people for answers. It has to be US thread sizes so at least you can start there Or just re-tap for the size of screw you can find. Its possible the threads are screwed up, after all its only been 60 or so years :) And yes I had a SB Heavy 10, made in 1943.

A set of taps is handy for checking threads.

Try asking in a sb lathe group. there are plenty online.
Bill

Update: watch how to make them, do yu hav a brass slug under the screw.

https://www.youtube.com/watch?v=g_80bo5Ygvk

https://groups.yahoo.com/neo/groups/southbendlathe/info

Thanks Bill, I will watch the video. I just joined the Yahoo group.
No I do not have the brass slug but I figure I can make that pretty easily.

Our just buy a brass thumbscrew at the hardware store.

After watching the video Bill found I realized it was a 10x32 screw not a 12 as I said above. I guess I knew that but my memory is not what it use to be. Anyway I went to the barn last night and turned in a 10x32 screw. When I hit the resistance I had encountered before I turned a little harder since I knew I had the correct thread d woud not damage the threads. There must have been dirt as I got by that and the screw turned in.
So I am all set except for the brass nub I need to make. Thanks to everyone for their help.

That's why I asked about the ID.

So I am all set except for the brass nub I need to make. Thanks to everyone for their help.[/QUOTE]

That brass nub can be almost any softer metal or plastic. Al or Cu wire, hard plastic, maybe even hard wood. I would not use lead or solder as it may mushroom out and jam the threads. Just use something softer then iron but not too soft.
Bill

Yes Bill you are quite correct anything sofer tha see will do. Now I need to find the time to get on it!