Removing treadmill motor pulley/converting to V sheave

Thanks for all the suggestions. Looking around online makes clear that there are many approaches to this. The first treadmill I scrounged had a nice 56 frame motor on it. A very high end residential item, I think. Definitely worth looking for something like this, as Phil suggested. Makes it a lot easier! Some people will be lucky and have a drill press with poly-vee sheaves, otherwise making the job a lot easier.

Kernbigo said:

the 1 i used on my south bend has a external fan, you need a fan fosure or it will over heat at low speed

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Yes, a motor with a fan on the back end gives more flexibility as you can take off the sheave/flywheel/fan unit and put on whatever you want. Some people put a tin can over the fan to protect it.

Actually CW is correct for a lathe too if motor mounted behind and pulley on left side
I would toss the existing fan and plan on an external one since the original fan won't move much air at slow speeds anyhow.
Mark

I've done a couple of these and am about to do another one on my mill.

Flywheel vs. no flywheel - the flywheel provides cooling and rotational inertia, so if you take it off you'll have to fashion a replacement fan and the motor is more likely to slow and surge under interrupted cuts. I tried it and ended up putting the flywheel back on.

Poly V vs. A section V belt - I've done exactly as suggested above, cutting the Poly V part of the flywheel down and then putting a small V section pulley on. I used a home made arbor to mount the flywheel to the lathe. I used a set screw in the pulley for added insurance, then mounted the whole shebang (rotor and flywheel) between centers and trued up the pulley to make sure it was running true. Didn't take much. One big tip though - use AX cogged belts. Because treadmill motors run at ~4000rpm full speed, you need the smallest V pulley you can get on there and AX cogged belts cope better with smaller pulley sizes. My build should be on here somewhere under mattthemuppet username.

I've also used the poly-V flywheel as is by mounting the matching poly-V pulley off the roller on the countershaft of my lathe. Works REALLY well with no slip whatsoever. I'm in the process (much delayed) of making poly-V pulleys for the countershaft to spindle. I've made the countershaft poly-V step pulley, just need to make the spindle one, which is a fair bit more involved!

for the mill, I'm going to make a stub adapter to attach to the poly-V sheave so I can mount the original step motor pulley, but at some point in the future make a poly-V pulley to mount to the idler pulley.

for preference I'd use poly-V belts, but for convenience the V-belt approach is a lot easier

I am a big fan of poly-V and variations. They can wrap a lot smaller so you get a lot more flexibility in designing the drive, and they can transmit a lot more power without slip. There is really not much reason other than habit for using regular v-belts. Existing equipment, clutching drives, maybe there are other reasons. But for a treadmill motor on a drill press I'm still not satisfied with my options. Some people cut a v-groove in the existing flywheel, but with the OD of that being about 1.4" the result will be too small for a good v-belt sheave. On the other hand, even an AX sheave should be around 2" plus for good service, and that won't let the treadmill motor run in it's effective speed range. Still thinking this through......

I think that V pulley on the motor on my drill press is 1.5" and it does fine with a Gates AX belt. The idler to spindle belt sometimes slips, say when using a large S&D drill, but the motor to idler one doesn't.

I'm still thinking through my options with the mill. I'd prefer to use a poly-V belt, but that would entail adding a poly-V pulley to the idler pulley. Not impossible but if I used the smallest position that would lose me my lowest idler to spindle ratio (v. handy with a treadmill motor). If I used the largest position I'd have to turn down the pulley a fair bit and mount the treadmill motor really high up. It's a lot of work when making a stub arbor and reusing the exisiting pulley would get me most of the benefits.

the controller on my lathe is a danfoss 2000, i run the bandsaw and the lathe off the same controller, just not both at the same time.