[ZipSnipe]

I am doing a powerfeed mod for my milling machine. I am using an old 14 volt Ryobi screwgun motor. I was wondering if I could use a 20 volt 3.5 amp power supply(wall wart) I have to run it?

I also am using a 12v36v rated speed controller for it.

[Al_The_Man]

As long as you limit the max output voltage, so you do not have a over speed problem, also best if the speed controller has current limit whether the correct voltage or not.
It is normal for the drive voltage to be rated at least 10% above the motor rated.
Al.

[underthetire]

That brushed motor will pull more than 3.5 amps!

[ZipSnipe]

Another guy on another forum, built the same powerfeed mod using the same motor. He said he tested it and barely pulled an amp under load. Plus the clutch will keep it from pulling too many amps, according to him.

But he used a 12volt pwr supply

[H500]

I believe screw guns have electronics built in to control the speed. If you use 20v, you risk exceeding the rating of the transistors and causing them to fail.

[Al_The_Man]

I also am using a 12v36v rated speed controller for it.

What is the nature of the speed controller?
Al.

[ZipSnipe]

H500 the motor is stripped out of the gun no electronics from the gun are being used other than the motor which has 2 wires coming out of it.

The nature of the controller? this is what I bought New PWM DC Converter 12V 36V 10A DC Motor Speed Adjuster Controller Driver | eBay

Please note while the heading says 10 amp what I received was a 5 amp

[Al_The_Man]

I imagine there is not much in the way of current limiting, you may want to fuse it fairly close.
Al.

[ZipSnipe]

Thanx Al, I think i will dish out and buy the power supply I need, its only $9 delivered

[H500]

Since that controller is rated up to 36v, it should be no problem to use a 20v supply. Speed controller without some sort of feedback don't work very well. The speed varies inversely with the load.