The headstock

I've been enjoying tinkering with the lathe, which was the point after all. I put the new back gears on, no problems there to speak of.

I pulled the spindle off. Due to heinous hackery the spindle's bull and back gear didn't line up with the mating gears on the back gear shaft. It was an adventure getting it apart. The biggest problems involved set screws - a previous owner had cranked them down so tight they left divots on the spindle. The divots prevented the close-fitting gears from coming off the spindle.

As I examined the spindle, I discovered something very wrong with it. The 'path of thrust' through the spindle was plain crazy. When you put something in a lathe, you normally squeeze it between the headstock and tailstock. Or the manipulate the cutters in such a way as to push on the headstock. This can transmit a lot of force to the thrust bearing in the headstock. With this lathe, the path of force was:

The nose
The spindle
The bull gear's set screw (!)
The bull gear
The cone pully
The back gear
The ball thrust bearing

That is not correct at all! None of the gears on the spindle should be in the path of thrust! One thing I noted was that the spindle was a 1.25" OD rod. The right 80% of the spindle has a steel sleeve that brings its diameter up to 1.5". Why is this? One reason is that the step formed at the left end of the sleeve is a dandy place to put a bronze flange bearing. This transfers the force to a ball thrust bearing that's against the left babbitt bearing.

So with this scheme, the path of force is:
The nose
The spindle
The bronze flange bearing
The ball thrust bearing

Much better!

As I was planning this out, I noted that the back gear isn't really attached to the pulley. There's nothing to keep the back gear from sliding around. Previously the thrust bearing kept the gear captured and led to the silliness described above. The back gear rides on a brass bushing that protrudes from the pulley. I'll pull the bushing out a little, perhaps 3/8", mill a groove very near the edge, and use a spring clip to capture the gear.