I have a 7 inch angle grinder/sander that I use for heavy duty sanding. It only has one rpm speed which is often to fast for what I need. I would like to make it variable speed like my smaller sanders. A long time ago I heard about a device you could attach to the power supply of a tool to make it variable speed. Are these devices still available? If so where would I find one? Would they harm the sander? Thanks for your time and expertise.
Arthur
Replies
Arthur,
If your sander has a universal motor, which is almost certain, you can plug it into a variable speed control. If your sander has a universal motor it will have brushes, usually accessible under two small removable covers, at the power cord end of the motor.
A variable speed control is a simple box with a speed knob that the tool's cord just plugs into. The controls won't work with soft start motors but your sander is unlikely to be a soft start.
A variable speed won't directly damage a motor but there is a risk that you can overheat the tool while running it at lower speeds since there is less cooling air being drawn through it, so just don't push the sander too hard when running at a reduced speed.
I found a speed control in the Woodworkers Supply catalog, for around $45.00, and I have seen them in several other catalogs.
A variable speed control is basically just a modern light dimmer, so you can wire your own from ordinary electrical parts if you want.
John White
Edited 11/8/2007 12:07 pm ET by JohnWW
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