South bend 16" lathe accessory question

I'm working blind here, knowing only the SB 9" version. That one is a short slice of a female dovetail, with a screw on one side to clamp it to the apron ways. There is a hole right in the middle which is a clearance hole for a bolt. This bolt is oriented horizontally, crossways to the lathe axis, so it points straight at the end of the cross-slide. The bolt fits through that hole and threads into a hole in the operator's end of the cross-slide table.

Is yours like that? See Fig. 225 on page 76 in "How To Run A Lathe".

Anyway, you have the threading stop, so you can measure the clamping hole in the side, and you have a SB cross-slide table, so you can measure the hole for the stop bolt.

Grant

How Far in is the bolt threaded? How long is the bolt? and What thread is on it? The Thread stop hole does not have any threads in it.

Yes I have the threaded hole in the cross slide, But I have no way to measure the TPI in such a small hole. I've tried to thread in some bolts laying around the shop and none fit. I'm guessing the first thread is "bunged up". I'm afraid to tap it without knowing the tpi.

Thanks For the suggesti>

It's likely 1/4-20. Measure the clearance hole in the threading stop itself - if it's slightly larger than 1/4" (e.g. .251-.260") then it's almost certainly

1/4-20 thread. Remember, mine is on a 9" lathe and yours is on a 16" lathe, so I really have no way of knowing. I suggest you put on some good reading glasses, use strong light, and *look* at the hole in your cross slide. Have a 1/4-20 bolt handy to compare it. If the threads look right they almost certainly are right.

If it isn't 1/4-20 then it's probably 5/16-18 or at most 3/8-16. South Bend used standard threads.

If I were you I'd just thread in a tap, using a little force if you have to. You can always put in a helicoil if the thread is destroyed.

The bolt is as long as it needs to be. Try a 2" bolt. If that isn't long enough, then try one longer - if it's too long, try a shorter one.

GWE

I made one out of a chunk of key stock as a first project when I got the shaper. Length really isn't critical, the threads in my cross-slide were 1/4-20. I just went down to the hardware store and got a socket-head capscrew with an unthreaded shank just a little longer than the stop block was wide. It's very uncritical, all you need is enough shank to back the cross-slide out of the cut without nicking the surface on the traverse back to the start. Mine is something like 2 1/2" long, YMMV. The other part of the setup is a carriage stop so you can back the tool out of the cut at the end, run things back to the beginning where the stop is and start over without a lot of squinting. Speeds things up a lot. The hole size in the stop itself should give you a clue as to the bolt size, it's a sliding fit. You could very well have a buggered thread or two in the cross-slide hole, I keep a short capscrew in there to keep crap out and protect the threads when not using the stop. An old dodge, cut a sliver of wood, "thread" it into the hole, back it out and use a thread pitch gauge against the marks to see what it's closest to. Then just use a matching tap to run the threads, SB used standard threads. You could even use the stop itself as a tap guide.

The SB manual really isn't that clear on how the thing is supposed to work, mine is a well-worn copy and the pictures aren't that clear. When I finally figured out what it did, I had to have one. SB had a ridiculous price on it back then and I was a starving student, so I made one. My threading speed and thread quality picked up a lot after that. Well worth the effort.

Stan

Thanks for the feedback. Stan, I really like the wood dowel idea. There's always an easy way to do a simple task. I'm just never the one to think of it.

Thanks to all for the great ideas and information..

Ted