speed reduction with variable input power?

[tprowood]

I've been reading about DIY speed reducer and the expensive SS reducer, and a crazy thought occurred. Can I simply use a variable speed control, much like a ceiling fan, to vary the speed? Essentially a DIY electronic speed control. Would that work, or would it burn out the motor?

[edma194]

Wouldn't work. The Shopsmith motor is an AC induction motor, it's speed is based on the line current frequency, not voltage.

[tprowood]

I'm beginning to understand that better, after more digging and reading. Thanks for the reply.

[tprowood]

Has anyone retrofitted step pulleys onto a SS Mark V / 500 Headstock, much like the 10ER, as a way to get speed reduction? I've had bench top drill presses that had step pulleys, with speed ranges from 350-3300.

[edma194]

Has anyone retrofitted step pulleys onto a SS Mark V / 500 Headstock, much like the 10ER, as a way to get speed reduction? I've had bench top drill presses that had step pulleys, with speed ranges from 350-3300.

In this thread there are several mentions of a "jack shaft" that can be used that way: viewtopic.php?p=272374&hilit=jack+shaft#p272374

There are other threads that discuss this subject and a video on the My Growth Rings about speed reduction with a DIY jackshaft: https://youtu.be/5ZNIDkewy0U?si=fDnX2JLdGfgHRJ90

I acquired a used Shopsmith Speed reducer at a good price. I don't see those on eBay or Craig's List very often. You have to be careful with a used speed reducer, the internal belts need servicing. Shopsmith used to offer some kind of refurb for a fixed price, don't know if they still do.

[benmcn]

I saw a shopsmith listed in my local classified several months ago that had an interesting modification. The seller used his machine exclusively for lathe turning. It looked like he removed the upper poly v belt but left the drive belt on. The seller had a large pulley attached to to the upper auxiliary spindle and a small pulley attached to the lower auxiliary pulley with an appropriately sized belt connecting the two pulleys. (At least that’s what I remember… but then my kids are always questioning my memory). Essentially he used the shopsmith hubs to make a Jack shaft. I have no idea what kind of speed reductions the seller achieved or even if it worked.

[tprowood]

Benmcm - that's what I'm thinking about, but, using a step pulley on each Spindle. I'll post any progress I have.

[JPG]

The shortness of the idler shaft may be a problem.

BTW the upper poly-v(or gilmer) belt needs to be removed and the lower motor v-belt retained.

Pix above accurate, description not so.

[edma194]

Not sure how slow you need to be. Whatever reduction ration you have goes on top of the 5:1 reduction in speed from the sheaves already. So 2:1 reduction would get you down to 350 RPM, 3:1 down to 233 RPM, and it's all variable through you speed dial. You probably don't need step pulleys after that. If possible it might be worth getting a second machine or just a headstock for this purpose so you don't have to disassemble anything to remove the V-belt or Gilmer.

ETA: Forgot about the reduction between the aux and main spindles. So there's a 1.6:1 reduction ratio now missing. So you may need to get to that 3:1 pulley reduction to get down slow enough. Depends on what speeds you're looking at.

[miken]

Maybe find and retrofit one of the old style speed changers?
(Photo courtesy of Everett Davis)