Variable belt speed

[Rick B.]

I'm thinking that I'd like to have a variable speed option on my Craftsman 6/48" belt and 9" disk sander. The motor is 110v, 3/4hp. Can it done? Would I be risking damage to the motor?

If it's doable would I keep the original push/pull switch (in yellow) and add a separate rheostat to vary the speed or would I replace the push/pull with a combination on/off - dimmer type switch? Thanks in advance.

View media item 111481

 

[seber]

You would need to replace the motor with a DC or three phase. It would most likely be cheaper to just buy a better unit.

 

[Renegade1LI]

I would look for an older delta or powermatic 3 phase machine, add a vfd and you're set. I picked up a pm 30 with dust collector for 250$, it's great having vs., Cleaned and painted its like as new machine.

 

[Maui]

You can do it by setting up a mechanical variable speed using a Reeve’s drive pulley. You just turn a handle to vary the speed. I have a 1/2 hp motor set up on a self-contained fixture with the handle readily accessible to be used on whatever machine I like. They work nicely when set up correctly.

 

[lilredex]

You can do it by setting up a mechanical variable speed using a Reeve’s drive pulley. You just turn a handle to vary the speed. I have a 1/2 hp motor set up on a self-contained fixture with the handle readily accessible to be used on whatever machine I like. They work nicely when set up correctly.

Got a picture and more details?

 

[Maui]

I’ll see if I can get a picture of mine. It may not be until next week.

 

[whateg01]

I have a similar machine but have been wanting to build a belt grinder to replace it. Recently I thought, why not replace the motor on this with a bigger 3ph and get vs so that's the direction I'll go when I get a round tuit!

 

[Renegade1LI]

One good thing you can find 3ph motors relatively cheap & usually baldor or another good quality brand.

 

[redragoon]

Would a solid state, single Phase 115V Fan Speed Controller work?

You would need to spec one rated for the maximum amps of your motor, but it could work.
https://www.grainger.com/product/DAYTON-Speed-Control-48C172
https://www.grainger.com/product/FANTECH-Speed-Control-15W823


Check the motor type to see if it is compatible.
WARNING
it is compatible with any universal AC/DC brush type motor 15 amps or less.
NOT for use with the following types, brushless, induction, shaded pole, and soft/slow start motors.

 

[Rick B.]

Here are the specs on my motor. Is it suitable for using the single Phase 115V Fan Speed Controller without damaging the motor?
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[The Cobbler]

good place for a DC treadmill motor !

 

[matt_i]

The economical choice is a set of matching step pulleys and a takeup to tension/loosen the belt.

I don't think any Reeves Drive (vari pitch sheave), new, is going to be cost effective when you start pricing them.

As mentioned DC motor + controller or go over to a 3 phase motor of same frame size, wire for 240vac and use a VFD. There are some specialized VFDs which require 120vac single phase input and produce 240vac x 3 phase output, for lower HP applications. They are not the friend of a GFCI circuit though.....

 

[whateg01]

The economical choice is a set of matching step pulleys and a takeup to tension/loosen the belt.

I don't think any Reeves Drive (vari pitch sheave), new, is going to be cost effective when you start pricing them.

As mentioned DC motor + controller or go over to a 3 phase motor of same frame size, wire for 240vac and use a VFD. There are some specialized VFDs which require 120vac single phase input and produce 240vac x 3 phase output, for lower HP applications. They are not the friend of a GFCI circuit though.....

I wouldn't go to a same size 3ph motor. As you slow an AC motor down, the torque drops off. If the goal in VS is to get slower speeds, you won't have enough torque to run it. I can stall the motor easily on my similar machine with a 1/3 HP motor on it. They say for belt grinders, 1 HP per inch of belt, IIRC. Even in wood, I would now try for something like that. It would be hard to fit a 1 HP motor in the place of that one, but if you are going to the effort to upgrade it, then upgrade it. A DC motor would be a better choice for slow speeds, as they can generate huge amounts of torque even at 0 rpm.

 

[Renegade1LI]

I wouldn't go to a same size 3ph motor. As you slow an AC motor down, the torque drops off. If the goal in VS is to get slower speeds, you won't have enough torque to run it. I can stall the motor easily on my similar machine with a 1/3 HP motor on it. They say for belt grinders, 1 HP per inch of belt, IIRC. Even in wood, I would now try for something like that. It would be hard to fit a 1 HP motor in the place of that one, but if you are going to the effort to upgrade it, then upgrade it. A DC motor would be a better choice for slow speeds, as they can generate huge amounts of torque even at 0 rpm.

I have a powermatic model 30 6 x 48 belt with 12"disc, 3 hp, 3 phase running of a vfdxi can sand anything at any speed without stopping it. 3 hp should be more than enough, also add a graphite pad below the belt on the platten, it will run cooler and smoother.

 

[Maui]

The economical choice is a set of matching step pulleys and a takeup to tension/loosen the belt.

I don't think any Reeves Drive (vari pitch sheave), new, is going to be cost effective when you start pricing them.

As mentioned DC motor + controller or go over to a 3 phase motor of same frame size, wire for 240vac and use a VFD. There are some specialized VFDs which require 120vac single phase input and produce 240vac x 3 phase output, for lower HP applications. They are not the friend of a GFCI circuit though.....

Why buy a new Reeve’s drive pulley? I always bought them used. They are not expensive at all when you buy them used.

 

[seber]

Here are the specs on my motor. Is it suitable for using the single Phase 115V Fan Speed Controller without damaging the motor?
View media item 111493

Single phase induction motors can only be slowed by changing the input frequency. Fan controllers are for universal or DC motors.

 

[Rick B.]

Ummm, not that I understood all the VFD, Reeves drive, VS, vxdi, IIRC talk, I'm guessing the general consensus in no, I can't just use a dimmer type switch.

 

[BukitCase]

Dunno about your area, but here in Oregon I see quite a few treadmills either cheap or free - they usually have at least a 1 horse motor, virtually ALL are a DC motor and controller - you might have to work at it a bit, but that would be a LOT stronger running than any of your other options - kinda depends on how much of a tinkerer you are, and how "attached" you are to the sander you have... Steve

 

[Maui]

Here is the Reeves drive motor setup that I have. The handle at the bottom of the photo can be rotated to physically move the motor along the platform it is mounted to. This engages the Reeves drive to change the speed. It works well.

Maui

 

[Rick B.]

Thanks for all the responses. I appreciate your thoughts and ideas.