Can I make this slower/variable speed

[Neil Bosdet]

Hi all,

I bought a pneumatic drum sander:

http://www.busybeetools.com/products/SANDER-PNEUMATIC-DRUM-AND-FLAP.html

I was going to make my own but this was much easier and cheaper. The problem is it goes too fast. 1725 rpm. I'd like it to go about 1/2 that. Is there a way to achieve this or make the motor variable speed with an option like this:

http://www.amazon.com/gp/product/B001JHQ3G8/ref=ox_sc_act_title_1?ie=UTF8&m=A2GCZA90HY2BIS

I'm not sure about the electronics part of it and am looking for an easy solution that won't damage the motor.

Thanks.

[Mike Henderson]

It looks like the motor on that sander is an induction motor. If that's correct, that speed control won't work. It's possible to connect a VFD (single phase) to the motor but the cost would probably be prohibitive.

Mike

[Added note for readers: it is possible to control a single phase induction motor with a VFD. The issues are (1) starting, which can be done at 60Hz, and (2) the question of what RPM the starter switch kicks back in (as long as you keep the RPMs above the that speed, you'll be okay)]

[Chris Fournier]

I'm curious as to why you want to go slower than 1725. Your corresponding feedrate will have to drop as well as the RPMs if you slow the works down. All of my sanding equipment runs at mfgrs speed and I have no troubles. A delicate touch takes practice on some of the equipment and this is how I get a bit of fidelity.

[Neil Bosdet]

I'm curious as to why you want to go slower than 1725.

My friend made his own pneumatic drum sander with a motor enclosed at the base of a cabinet with a pulley system. He has it set up at approx 1/2 speed. I did a fair amount of work on it recently and found the speed wonderful. I couldn't feed the work any faster nor would I want too. It was a very controllable situation.

[Perry Holbrook]

It's a shame that type sander comes with a single phase motor. A 3 phase motor can easily be controled with a VFD and not cost more than about $100. I actually use a direct current motor with a VFD for my flap sander. I got a real education last year while attending the woodworking trade show in Atlanta. I was in the market for a better flap sander head. What I found out was my main problem was I was running my current one too fast. All the industrial units suggested running at 600 to 900 rpm. I know SandRite heads recommend about 1100 rpm. When you "sand" faster than that you are not letting the paper do its work, but are actually polishing the wood. I do use a higher rpm (around 1500 rpm) with a Mac Mop because I want to polish with it before spraying the finish.

Also, I think most of the guys that turn on a lathe, recommend sanding at around 600 rpm as well. Seems they have figured it out as well.

Perry

[Neil Bosdet]

I was back at my friend's shop this afternoon and his pneumatic drum sander is probably going at 1/4 the speed of mine. Probably around 400-600 rpm. Much better than mine at 1725.

[Dan Friedrichs]

That router speed control you linked to only works for "universal"-type motors, not induction motors.

As Mike said, you can hook a VFD to it, but it will take a bit of tinkering to get it to work, and will probably cost you $100-200. That's the only non-mechanical solution to your problem.

For less money, you could probably just buy a shaft with a pulley, mount the sanding drums on it, and run a belt to the motor you have.