Can I Use a Router Speed Control on this Moter (Please see photos)?

[I Gotta Tell Ya]

Yikes, sorry these photos are so monstrous. This is AFTER I resized them.

Anyway, below is an inexpensive "Router Speed Control" unit sold by Harbor Freight. It says it will work on "any universal AC/DC brush type motor, 15 amps and under." I'm an idiot when it comes to electronics.

Below are some photos of a little project I am working on for my shop, re-purposing a kitchen juicer to run a buffing wheel. The motor runs at about 8000, which will likely be too fast for my application. Again, excuse my ignorance, but will a speed control unit like that pictured above work on the motor below? Is the motor pictured below a "universal AC/DC brush type motor?" Thanks so much for your help. Appreciate it.

 

[catsparadise]

That looks like it's a universal motor. A universal motor is just a DC motor with the stator and rotor connected in series, that way, whichever way the voltage is applied the magnetic fields conspire to push it round in the same direction. I can see what looks like brush housings on the PCB material at the fan end.

I imagine that the speed controller will either control the duty cycle of the AC supplied to the motor or will rectify it and use some sort of pulse width modulation to generate a variable average DC level to control the speed. So the short answer to your question, in my opinion, is yes, it will work. I could be wrong, but the controllers aren't that expensive (found an identical one on ebay, finest chinesium, for sub $20).

Rob

 

[Bi11Hudson]

I am apparently going blind in my old age. I also see the brush looking plastic on the fan end. However, the brush rigging doesn't look like it's on opposing sides. The stator windings look more like a shaded pole motor, and/but there is also a capacitor in there.

In any case, I personally would recommend against using a light dimmer /router speed control. A "router" speed control is basically a light dimmer with beefier components. The final output is not a true "sine" wave and will cause severe heating on an induction motor. The extent of heating will vary depending on how much speed reduction is used, how far below base speed it is run. i.e the slower it runs, the hotter it gets and the less power it has. If it's important, change the motor, using a drill or the like.

The only "safe" motor will have brushes 180 degrees apart, such as a hand drill, router, or sewing machine motor. As stated, a "series universal" motor... An AC/DC motor. The full answer requires a working knowledge of electricity, not electronics. There is a vast difference and I find myself trying to answer properly without going into an electrical education.

Bottom line, if the motor doesn't have brushes, don't use a speed controller or lamp dimmer. Period!

Bill Hudson​

 

[RobertB]

Better pics of the brush end would help, where you could see both brushes and the commutator at the same time, but it appears brushes 180 degrees apart to me. I also do not see a capacitor, only other thing I see looks like a thermal protector zip tied to the windings.

 

[Flyinfool]

An induction motor that is running on 60Hz power has a max speed of 3600 rpm. That means that if this one is running at 8,000 RPM it is not an induction motor. Odds are it is an AC/DC motor and will be fine with the Router controller. BUT pay attention to heat, that motor looks very small to be running a buffing wheel, as you slow the motor down the fan is also slowing down and giving less cooling air, you have also removed all of the ducting that kept the cooling air close to the motor. Watch out for the magic blue smoke. all electronics run on magic blue smoke. If you let it out it will stop working.

The way the router controller works is that it chops off the AC waveform from the zero crossing first and move that cutoff point wider toward the peaks. this means that the motor is still getting the full peak voltage. Simply reducing the voltage will cause motor heating, by modifying the wave form there is less power available but it is still at the correct voltage.

 

[markba633csi]

Light dimmers work in a similar way, they are called "phase-fired ac controllers"

 

[I Gotta Tell Ya]

Thanks, everyone. I really appreciate your time and expertise. If necessary, I can take some more photos.

One main question I have at the moment. If I plug in this motor to the speed control unit and it is not the right motor, will it burn out the motor or in any way damage it? Also, assuming this works, is it realistic to assume I might be able to back off the motor to the RPM ranges of, say, 1000-3000?

Thanks again, and will check back in a bit.

Thanks!

 

[RobertB]

that motor looks very small to be running a buffing wheel,

That is an important point. That motor is only 140 watts, so you are in the range of a dremel tool power. You are not going to be able to drive a very big buffing wheel. 1" to 1.5" maybe. At that diameter to get the SF/M needed for buffing you will need the full motor rpm.

 

[vtcnc]

That is an important point. That motor is only 140 watts, so you are in the range of a dremel tool power. You are not going to be able to drive a very big buffing wheel. 1" to 1.5" maybe. At that diameter to get the SF/M needed for buffing you will need the full motor rpm.

^This reply should be considered first before you dive into the electrical part of the project.^ The size of the motor, rpm needed, etc. is highly dependent on the application. What exactly are you trying to achieve here? There are small buffing wheels and big buffing wheels, the extreme ends of the buffing wheel size spectrum shouldn't even be on the same tool let alone the same motor.

With that said, you have received some sound advice on the electrical side. If you are considering a purchase of a router speed control, why not purchase a cheap tool to run the appropriate size buffing wheel for your application? Harbor Freight may be your best friend in this case.

 

[I Gotta Tell Ya]

That is an important point. That motor is only 140 watts, so you are in the range of a dremel tool power. You are not going to be able to drive a very big buffing wheel. 1" to 1.5" maybe. At that diameter to get the SF/M needed for buffing you will need the full motor rpm.

Thanks for your advice on that.

Actually, to clarify, this motor is from a home juicer -- a Juiceman -- and has pretty good torque. What I'm actually using it for is buffing and polishing and lapping the guitar picks I make, which are all made of plastic, so my main hope is to run this with very fine grit ratings of 8000-12,000, with very little resistance. I'm not grinding or sanding stone or metal. It should work fine for my purposes, but will know more once I try it.

Does this make more sense?

Sorry if I created any confusion.

best,
IGTY