Thread: Multipurposing a 1500w/4450rpm motor

Hi on my lathe motor now attached to my band saw it has a pulley with multiple sizes so you could change the lathe speed. Might be worth getting a pulley like that.
Oops just read where you said multi size pulley!

When gearing down, torque multiplies up accordingly although there will be some losses from the use of pulleys.

I'd forget about the interchangeable powerhead bit (been there and done that and it's a right PITA0
The effort and complications needed to make setups that will allow for ease of interchangeability will far outweigh the cost of another motor especially if you look around for used motors.

Another really good use for an old table saw is to make a metal cutting saw out of it.
My old 8" table saw (it's more than 40 years old) has been my metal cutting saw with a thin kerk cutting wheel on it for the last 7 years and I love it!

RSG, If the motor is rated at 4450 RPM, it would have to be a universal (brushed) motor. These motors generally have a lower efficiency and torque than your general purpose capacitor start induction motor which would be rated for around 1440 or 2850RPM. If it is a brushed motor, it most likely has a fairly open casing to get lots of cooling airflow, due to the lower efficiency.This leaves them prone to dust accumulation causing bearing and overheating issues.

If the motor is rated at 1500W (2HP) input power, it can probably produce around 1HP (750W) output at the shaft. Couple the unit via a belt drive at possibly 80% efficiency and you don't have a lot of torque or power to do serious work. I suspect that a 12" disc sander might be the limit for the motor, or possibly too much if you wish to make the sander work hard.

Likewise, I suspect a thickness sander would be way too much for the motor, unless you are looking for a a simple surface finishing unit rather than something with genuine thicknessing capability.

A spindle sander might be a good option, as for something with 1/2 to 3 inch bobbins and sleeves the motor could operate at rated speed direct drive. However dust shielding would probably be an issue.

Speed variation is possible with fairly simple triac style circuits, but the speed will be load and voltage dependant, unlike the induction motor where the speed is dependant on the mains frequency.

Hope this helps you establish some workable plans.

Originally Posted by malb

RSG, If the motor is rated at 4450 RPM, it would have to be a universal (brushed) motor.

My experience with those old Ryobi motors is that they are very noisy too, and scream like mad when they're running.

Thanks for the input folks. Much appreciated.

BobL: Not a bad idea for a dedicated metal saw, but I don't think I'd use it very much. The rare times I work with metal is usually making pretty small pieces and best done grinding and filing. What I could most do with is a wet tile cutter for cleaning up all the old slate roof shingles I have earmarked for chessboard pieces (and I was just going to get a crappy Ozito bench tile-saw for that).

The hassles with an interchangeable motor are also duly noted.


Malb: Good point on the dust issue. I had figured that I'd enclose most of the motor in a case to protect it a bit. I could also always drop the disc sander size down from 12" to 10" or so just so that I'd have something that I could use. A disc sander is kind of the last real machine that I need (or could really do with) to complete my setup. But of course if it's all too expensive to hack one together, I might as well just buy Carba-tec's little doodad.


Colin: You're darn right. This thing literally SCREAMS when it's running. I thought my 3hp dust fan was loud, but this is just mental. It's certainly not a pleasure to use.


I guess I'll check out the price of the pulleys and the associated what-nots and figure it out from there. It's a horrible motor to hear running and I have big doubts about its longevity so maybe in the long run it's better to just trash it and go with a proper disc sander.

Ahh the burdens of being a tight-wad

Originally Posted by RedShirtGuy

. . . .Malb: Good point on the dust issue. I had figured that I'd enclose most of the motor in a case to protect it a bit. . . . .

You can't enclose it too much (not more than it is now as a table saw) as it will need cooling and even leaving it open just a bit still leaves it susceptible to dust. Mind you, being a table saw it could probably cope with a certain amount of dust anyway.

I know we all dislike waste..but if it is a brush type motor out of w a cheap saw bench......its probaly not worth it.

a good set of stepped pullies will cost you more than the motor is worth...possibly more than the price of a new whatever machine.

then there is the noise.

cheers