Sheldon 11-Inch Lathe Reversing Tumbler Repair - Again - Arg!

Sigh. Sometimes old machinery is a bit of a bother. Take for instance my Sheldon 11-inch metal lathe from 1941. I got it a year ago and the lead screw reversing tumbler casting was broken. It had been repaired previously any number of times but was broken again by the time I bought it. I fixed it shortly after I got it but noticed when the left quick-change gear selector was in position B, the gearbox would lock up tight. I looked into the issue a few weeks ago and found what the problem was. A pin inside the gearbox was too long, which would contact a gear when the pin came rotating around. I didn't want to pull the gearbox off so I tried to reach in with a cold chisel and knock off the end of the pin. I was somewhat successful, or so I thought. I rotated things by hand and the problem seemed to disappear. I put the lathe in gear, turned it on, and it seemed to run fine too. Shut it off, turn it on, shut it off, turn it on, shut it off. Cool, it's working. Turn it on again and whang! The braze broke. Again. Sigh.

Let me say it again. Sigh....

Nothing for me to do but to take the thing back apart. I ground out all the old braze material, then positioned the broken-off piece as best I could to settle in to it's rightful position on the main casting. I tried clamping the pieces together with a C-clamp like I had done before but it just wasn't working out, so I tacked things in place using my wire feed welder. That worked quite well.

Below are a couple photos of the part all brazed up again.

I wrapped the hot part in a rag to slow its cooling. Looks like I need to invest in a heat-resistant blanket, don't you think.

Now on to the gearbox to fix the lovely pin poking out that caused all this headache. I really wonder why the person that installed the long pin didn't remedy the situation at the time.

It really wasn't that difficult to remove the gearbox since the tumbler and other gears were already removed. One bolt and two screws, then knock out the taper pin in the lead screw, and the gearbox was off the lathe. In the below photo you can kind of see the errant pin poking into a gear.

The next photo is a better shot of the pin poking out.

I used my Dremel with a carbide bit to grind the pin flush. I first tried knocking the pin out so I could grind it shorter on the bench grinder but it wouldn't budge in either direction.

The tumbler is back in place on the lathe in the photo below. One thing I forgot when removing the tumbler was that the securing nut had a set screw. I couldn't figure out why the nut was so difficult to remove. Then I saw the set screw and remembered it from before. It had been hiding from view until I got the nut turned far enough to see it.

All back together and running nicely. Yay! Seventy-eight years old and running well once again.