Router Speed Controller on Angle Grinder?

[Perry Holbrook]

Will I have any problems using a router speed controller for slowing down the speed on a Makita angle grinder that now runs around 10000 rpm?

Perry

[Charles Lent]

You can use it with any motor that is rated for AC/DC use. This would be any motor that uses brushes and a commutator. These external speed controllers will change the motor speed OK, but they will also reduce the motor's output power as the speed is slowed down. They will work fine on fixed load uses, such as a fan, but will fall short on uses with varying loads, such as a drill, router, or grinder. Some internal speed controllers have speed sensing circuitry that makes up for this shortcoming by adding power to the motor as a load is applied to maintain the set speed, however this feature isn't available in an added on speed controller. You can try it, but you will probably not get the results that you are hoping for.

Charley

[Perry Holbrook]

Thanks, just wanted to make sure I wouldn't damage the grinder. I tried it this morning, and of course you are right about the varying load, but it will meet my needs. I'm grinding small defects from copper pipe and the full speed was generating too much heat and lower speeds give me more control.

Thanks again.

Perry