Sloan & Chace spindle thread classification

[Nate Crouch]

I'm looking for any advice acquiring tooling for a S&C headstock with "Square" threads. In going thru older books I came across that name and its classifications, but I'm not sure if that's correct. My goal is to get the lathe a # 5 to at least a usable state for general precise work but not any type of professional daily use. The only part for the headstock that came with the machine is a face plate. I assume acquiring a chuck that would screw on, and in a decent condition could be next to impossible? Would making a adapter be a good option? It doesn't seem wise to set up a modern chuck to hold in a collet? any workable solutions would be very much appreciated

 

[jim rozen]

Years ago I had some sloan and chace collets - for a milling machine. They are rare, but out there if search hard. It's possible to machine a backplate for a new chuck, I've done that on a number of occassions for lathes like that.

 

[L Vanice]

A common procedure for machining a new chuck adapter for a lathe with an unusual threaded spindle is to first make a very accurate copy of the threaded end of the spindle on a steel bar. Having an original face plate that fits the lathe will help in making the copy. The copy is then used as a gage to ensure a good fit in the threads and bore you cut in the new adapter. It used to be possible to buy unfinished and semi-finished cast iron chuck adapters, but I have not looked for one lately. You could also buy a finished adapter with a chuck that has a thread that is too small for your lathe and machine it to fit your lathe if the center of the adapter is thick enough.

The S&C No. 5 collet has a 1/2-26 thread and a maximum through hole of 3/8", so it is not much larger than a 10mm watch lathe collet and is smaller than a 3C collet. It is quite common for both 3C and 10mm solid collet arbors to be attached to small 3, 4 or 6-jaw chucks for use in small lathes like the Levin and Derbyshire. Those lathes do not even have any other means of attaching a chuck to the spindle. The picture shows three 3-jaw chucks on 10mm collet arbors. The two with brass rings were made by Derbyshire and the other is a Swiss chuck sold by Levin. Levin is still in business and has a current price of $8100 for that chuck.

Edit: Little lathes without ball bearings on the spindle can often have their spindle easily removed. That would probably be easier than making a copy of the spindle end for a gage.

Larry

 

[Nate Crouch]

Thank You Larry & Jim, For the in depth insight and advice. I take it that you guys feel it wouldn't be harm full to the headstock or spindle to hang a decent size modern universal chuck out of the bore? I'm not sure why that concerns me except that I assume it wasn't engineered with that in mind? Conservative instincts, I guess. I was incorrect in the previous post I also have what I'm guessing is a spindle thread protector ? which has a bit of a shoulder possibly to help hold the collet in the socket? I need to throw down for at least one collet to help work through all this. I also have a bunch of 3C stuff from my S.B. 9". if as stated they are larger, curious if there would be enough material to regrind. Will investigate. Is that spindle thread referred to as "Square thread" my older reference materials have quite a few names, and versions of styles...I 'm guessing that knowing its name could help any research needed to help in cutting internal threads. Thanks again!

Nate

 

[L Vanice]

It would help answer your questions if we could see pictures of your lathe. S&C is a rare make and I can only recall seeing two in the last fifty years, and did not pay much attention to either.

Note the chucks in my picture are quite thin and light weight compared to the proportions of an average three-jaw chuck of the same diameter. These chucks were designed for a particular class of small lathes that do delicate work.

I have no idea what type and size threads are on your spindle. Are you asking what a square thread looks like? That is easy enough to answer. Here are pictures of Hardinge feed screws from their 1946 model slide rest. The upper screw has a 1/2-10 square thread and the lower screw has a 1/2-20 square thread. The closeup shows the 1/2-10, which has a square groove .050" wide and .050" deep. Square means square. The thread flanks are at 90 degrees to the axis.

Larry

 

[Nate Crouch]

Photos, absolutely and of course. My inquires got ahead of my progress with the other aspects of the project. Honestly, I wasn't sure how much of a response I would get. Much appreciated Larry!

 

[L Vanice]

The pictures show the S&C spindle nose threads are not square form.

Larry

 

[JST]

At least they are not "anymore".

They do look more like a stub acme than square. But they also have a wear ridge, and the proportions suggest to me that the thread was wider originally. Hard to say if it could have been square, or was just a version of acme. I "think" it looks more as if it had been acme, but very worn square is also possible.

The threads are also beat to heck. Really pretty bad for damage as well as wear.

Looking at the Lathes.co.UK site, S&C shows square threads on a very similar looking headstock.

http://www.lathes.co.uk/sloan&chace/img9.jpg

 

[MrStretch]

Is gorked a thread classification?
Why would a maker use square threads on a spindle nose? I wonder if it looks like that because someone forced something non-square threaded onto the spindle. If so, it would be an indication of some serious abuse so if your intention is precision turning of some sort, you might want to look for another lathe.

 

[jdavi581]

The accuracy of square threads for centering a chuck would be questionable, and with the condition also being a factor, I think you may be better looking into the collet type adapter for this lathe. Hopefully the inside of the spindle is in better condition.
Joe

 

[JST]

With square threads, obviously their centering capability is nearly nil. That is the ONE case in which I would agree with the hobby forums where folks insist on the "register diameter" as the prime centering means.

Looking at the pic on Lathes.co, it surely looks as if that might be what was intended by S&C.

I agree that the collet socket (I assume the spindle is made with that) is likely the better option. The threads are surely chewed away.

Hopefully the inside of the spindle nose is not as "gorked" as the threads.

 

[jim rozen]

Another option for this machine is remove spindle, remachine the threads to a smaller diameter thread - or, turn it down to a cylinder and fab up whatever thread adapter you desire, and green locktite it on. Keep the old girl running.

Dave Sobel was a big (!) sloan and chase guy - probably because I think he was originally from the Newark area.