Router speed control

[Tony Pisano]

We do some dumpster diving at a local college at the end of the school year and get some great finds such as a brand new bullet mixer in box, samsung digital camera, and too many items to list.
I found a gadget that says it's a router speed control, made by Wand Essentials. Did some research and there are other brands which look like the exact same thing. They sell for anywhere fromm $15 to $24. I tried it out quickly on an angle grinder and a dremel tool. It did control the speed. I didn't try under load. The innards don't show much: fuse, bypass for full power, small circuit board that I can't get at to see components if any. The power cord is only 16 ga.

My question to any on the forum who are electricians is, will this device do any damage to the motors?

[Nick Decker]

My understanding is that they are fine for tools with only a single speed. If your router has an adjustable speed control, don't do it. The external speed controller will conflict with the router speed controller.

(I'm not an electrician.)

[Jim Becker]

In addition to what Nick mentions, they also cannot be used on tools that have "soft start", even if they are single speed.

[Carlos Alvarez]

To pile on to both of those correct answers...the issue is with two sets of electronics controlling the motor. If the device has a motor that is directly powered, no electronics, then you're fine. If it has electronic switching of any sort, it could be a problem.

[Bill Dufour]

dc motors only

[Dan Friedrichs]

It'll work on AC motors, but they must be "universal" motors (routers, shop vacs, etc), not induction motors. Universal motors are called such because they are capable of being powered by AC or DC, though

The speed controller is a simple circuit built around an SCR (silicon controlled rectifier), and wiki has a good explanation of how this can be used to vary AC voltage, which, in turn, varies the speed of a universal motor.

[marlin adams]

Having done small and large industrial motor repairs and rebuilds there is one rule of thumb that I learn from the old timers when it comes to speed controls for electric motors. If it has brushes it will work with a speed control as long there is no electric circuit control already on the motor like soft starts and such. If it is striaght power from outlet to motor via brushes then you can put a speed control on the circuit feeding the motor betweeen the outlet and motor.

[Bill Dufour]

Having done small and large industrial motor repairs and rebuilds there is one rule of thumb that I learn from the old timers when it comes to speed controls for electric motors. If it has brushes it will work with a speed control as long there is no electric circuit control already on the motor like soft starts and such. If it is striaght power from outlet to motor via brushes then you can put a speed control on the circuit feeding the motor betweeen the outlet and motor.

I wa s going to say brushes only but I have seen a few ac motors with brushes. older explosion proof and maybe repulsion/induction type.
Bill D

[Tony Pisano]

Thanks, all. It does have a sticker saying do use with brushless motors. My thought was it might be handy when using a handheld jig saw on those occasions where you want a slightly slower speed

[Carlos Alvarez]

Thanks, all. It does have a sticker saying do use with brushless motors. My thought was it might be handy when using a handheld jig saw on those occasions where you want a slightly slower speed

That should be DO NOT use on brushless. Not picking on you but that's a dangerous typo.

Brushless motors are timed by a little computer instead of the brushes. They are intrinsically variable speed and variable timing. Putting a PWM speed controller in front of what is essentially a computer will be disastrous.

[John TenEyck]

When the speed control on my 3 HP Hitachi router quite working, and a replacement was going to cost something like $150, I bypassed the circuitry and made it a fixed speed router. I plug it into a HF router controller, the same device the OP asked about, and it runs fine with good power over the range of speeds I've tried. As others have said, as long as there are no electronics between the new VS controller and the motor it will work.

John

[Curt Harms]

When the speed control on my 3 HP Hitachi router quite working, and a replacement was going to cost something like $150, I bypassed the circuitry and made it a fixed speed router. I plug it into a HF router controller, the same device the OP asked about, and it runs fine with good power over the range of speeds I've tried. As others have said, as long as there are no electronics between the new VS controller and the motor it will work.

John

I did the same with a P-C 8529 where speed control modules are known to be short lived and replacements are simply unavailable. I just removed the speed control/soft start module and wired it up like a simple AC motor and capped the 3rd red wire. I haven't used that router much but it seemed to work. If I remember to turn the RPMs down to minimum before starting it's effectively soft start. The speed controller also works on a Fein Turbo II shop vac.