How can I change speeds on my old lathe?

Question

I recently purchased a Shopmaster L-500 lathe. It has been restored to its original condition, unfortunately it did not include a manual. This particular lathe has a 4-stepped pulley in the headstock and originally had a 4 step pulley on the motor (though the restored motor has only three.)

Researching about pulley drives on lathes, I have heard mention of a Reeve's Drive, but I don't think that this is an actual Reeve's mechanism because there is no facility to push or pull the pulleys to move the belt.

Does anyone with an older vintage lathe have any suggestions on how to properly change the speed of the lathe?

Here's a view of the headstock and the pulleys inside:

And here's a photo at the motor:

Answer 1

I have the same lathe. I don't know how the previous owner changed speeds, as it was screwed to the workbench. When I got it home, I built a stand for it. I mounted the motor on a 2x6, which i fastened to the stand with a hinge. On the other side, I cut a slot to fit over a bolt that sticks out of the stand. So, when I need to change the speed, I just loosen the wingnut on the bolt, raise the motor on the hinge, change pulleys, set the motor down and fasten the wingnut. Takes all of 30 seconds to change speeds.

Answer 2

My PSI lathe was similar (though a bit smaller) and there was a locking mechanism that I had to loosen so the motor would 'raise' a little releasing the tension on the belt, then I could move the belt to what ever set of pulleys' I wanted.

One thing I noticed about yours is that the motor has fewer pulleys' than the head of the lathe. 3 vs. 4. Most I've seen have 1 - 1 in this kind of configuration. So as the head wheel gets smaller the motor wheel increases in diameter.

What I don't know is if this was designed to be a 4 speed (and the new motor doesn't have enough pulleys') or more like an 8 speed where you can use one or 2 pulleys next to each other, but that seems unlikely.

What ever you use to loosen the belt need to make sure when it is tightened it is fairly snug, since that will transfer more power to turn and less likely for the chisel to catch and hold the piece instead of cutting it.

Answer 3

I found some sort of "quick start" manual for this lathe here. In the parts list there the motor spindle also has 4 steps. It seems likely that the your 3-step spindle is not the original part, so don't be surprised by the belt not lining up for every position.

In any case, while it's not a full manual, it does say (emphasis mine):

To place belt on head stock pulley remove 3 Allen head set screws on bearing plate and remove shaft from Head Stock.

The bearing plate is:

So I imagine this is the procedure you'd to follow to move the belt as well, although I cannot say for certain what other steps may be involved. In particular it does not mention tensioning the belt so you may have to poke around and look for a release mechanism, if there even is one.

With your current setup you're limited to 3 speeds unless you can slide the motor spindle around a bit. I would not mount the belt at an angle.

I am certain that guide is for the L-500. According to some catalogs from the 50's (and one from 1953, with an awesome first page illustration) the L-500 was their only lathe at the time, so that must be the lathe.

Answer 4

My lathe is similar, though not identical, so this may not apply, but so long as you don't have too much tension on the belt, you shouldn't need tools and you shouldn't need to loosen and shift the motor each time.

(This also works for changing the speeds on a drill press)

The two pulleys are straight opposites of one another - as one gets bigger, the other gets smaller. This means that once the belt is on, regardless of which speed it is at, the tension required will be the same.

So, to shift speed, change belt positions like you'd remove a bike chain - push the belt on one pulley towards the next smaller sized ring, whilst turning (slowly and by hand!) the belt so that the rotation of the pulley pushes the belt off. Once it's slipped off the first ring, there should be pretty much no tension and you can shift the belt to the new position.

To get the belt back on, reverse the process.

Answer 5

I'll weigh in with the radical fringe - normal solutions seem pretty well covered.

In my personal experience, the best thing you can do is to swap the motor for an industrial DC or 3-phase motor and run that motor from a variable speed drive suited to what type of motor it is. These days 3-phase driven by a VFD seems to be most common/cheapest, though if you are willing to pick up craigslist free treadmills and take them apart, you may find a nice DC variable speed system inside it (with, IMPE, somewhat inflated ideas of its horsepower, but still fine for a mid-sized or smaller lathe.)

A that point, the stepped pulley is just a torque/top-speed selector.

It is a world of difference being able to get just the speed you want with the twist of a dial (and without the squealing of a Reeves drive.) Harmonic vibrations are easily avoided by making small speed changes.

Additional note - if there's room (there probably is) the "link or twist" belts are a much nicer way to change belts than pulling the spindle to change the belt. Since they can be twisted apart to change the number of links, you can get any length you like and break the belt to thread it onto the lathe, then re-make it, rather than pulling the spindle.

Whatever drive you use (including the fixed speed one) it's a very good idea to have a shutoff at BOTH ends of the lathe.