Router speed control issues

[toddmaci]

This is on my 3 1/4 horse plunge router. I am not using this on my bot. It has variable speed control. This is the problem. Sometimes it works other times it starts at one speed and them jumps to a higher one. I took the router apart,blew out all the dust from the speed control unit. This seemed to help for about a day.I priced a new speed control and it is $77.00. I am not sure it is worth it to repair seeing that I am not sure that is the entire problem. Does anyone have some other things to check before I decide to buy new or fix

Thanks,

Todd

[Gary Campbell]

Todd...
We have a dozen or so PC routers, many of them with the electronic speed control. IT is usually the first thing that goes on the router. In some cases we have eliminated them electrically and used the router full speed. I am not sure that is the best idea for a CNC application tho.
Gary

[shoeshine]

One cheaper solution is to hardwire the router as gary said and then use an inline speed control. It's really just a potentiometer that you plug the cord into. You might be able to salvage one for nothing (some fans, an old electric stove knob, etc.. just make sure it can handle the amps your router draws)and wire it up, or...

Harbor Freight has a plug in one for $20
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=43060

[dana_swift]

I must agree with only part of the previous advise, and issue a warning with part. A potentiometer, variable transformer or any other device that lowers the voltage to your router can damage it. Go that route with caution if you understand the possibilities. A speed controller does not work that way for good reason.

Motors are best thought of as "constant power" devices. If you lower the voltage the motor attempts to compensate by raising the current. The wire windings in the motor were designed for the current used when the router is running at its rated voltage. If you lower the voltage the current will exceed the capacity of the windings to dissipate heat. Blue smoke time, and end of router. If a fire occurs you may lose much more than your router.

Disabling the speed controller is also a tolerable solution, it just makes the bearings wear out faster because the router is always running all out. If you want to put a motor speed controller inline- go for it. A lamp dimmer is not a speed controller however. A ceiling fan speed controller is probably not designed for the sustained currents a router draws (10-15 amps) however it might work. Then they are cheap and most likely wouldn't hurt the router if it didn't work.

Sorry about the electrical engineer in me coming out.

Todd - good luck.. $77 may not be a bad investment over the cost of a new router. Keep us posted.

D

[shoeshine]

Hmm interesting, thx dana I didnt realize that. Is this true for all these aftermaket "speed controlers" like the HF one I linked to?

[steve4460]

Mine did something like this , and it turned out to be $5.00 brushes . I would try that first before ordering the speed control.
Bot on

www.windwardsgns.com (http://www.windwardsgns.com)

[dana_swift]

Very few things are true for "all" cases.

I'd consider trying the harbor freight device which is intended for the application. However that is not a rheostat.. its a pulse-width-modulator, intended to take a reactive load.

One thing I do not know about the PC speed controller, if the load increases and speed drops, does it automatically apply power to the motor to maintain the speed? I think it does, just from listening to mine. I hear the motor groan more under load, but the speed remains fairly constant.

An external speed controller could increase the "percentage-on-time" to the motor when the current increases to get a similar effect. That probably is more sophisticated than the HF part.

If someone has tried it it would be useful to know.

D