Tools & Supplies
Discussions on the latest and greatest tools, glues, and gadgets.
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cheep Rotor tool speed control box
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Texas, United States
Member Since: September 02, 2006
entire network: 785 Posts
KitMaker Network: 210 Posts
Posted: Wednesday, March 03, 2010 - 04:26 PM UTC
I needed to reduce the RPMs on my dremal tool, but didn't have the money for a variable speed control addon. So broke being the mother of invention I set out to build one for under ten dollars.

The parts you'll need are: a light dimmer switch, single gain w/ground recepticle, double recepticle box, switch plate cover, and a cord (in this case a discarded computer power cord)

The next shot shows how the wirring should look. First cut the female end of the power cord and strip the three wires (in most cases the black wire is hot, white is common, and green is ground), run the power cord wires through an opening in your box, The dimmer switch will have two black wires One dimmer black wire is twsisted too the power cord black wire and held with a wire nut. the other dimmer black wire is connected to the hot pole on the recepticle. Next run the white (common) wire to the neutral pole on the recepticle, Then connect the ground wire from the dimmer and the ground from the power cord and connect to the groung pole (green screw) on the recepticle. Screw the dimmer and recepticle to the box attach the face plate and dimmer control knob and your done.

It took about fifteen minutes to build and cost just under ten dollars, the cord was free and I work at the lumber yard where I bought the parts so there was a small discount, and for $10,00 there is one quick you should know about, The dremal tool needs to have about half power before it starts to move, but fron ther you can increase or decrease your speed. Using a celling fan control (designed for a bigger motor) will resolve this problem. Good luck from
Staff MemberConsigliere
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Florida, United States
Member Since: October 17, 2003
entire network: 15,338 Posts
KitMaker Network: 5,072 Posts
Posted: Wednesday, March 03, 2010 - 05:26 PM UTC
Been using my homemade speed control for over 30 years. Still going strong. It is a good idea to start at full speed then decrease it, your Dremil will last longer. Also speed it up, if you feel it getting too warm, as motors run hotter at low speed.
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Connecticut, United States
Member Since: April 02, 2005
entire network: 3,608 Posts
KitMaker Network: 512 Posts
Posted: Wednesday, March 03, 2010 - 05:41 PM UTC
Yep, I have one of these, too. Cost me $8 from Home Depot. I also made them for several other club members.
Also works for soldering irons, pyrogravures, and foam cutters.
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British Columbia, Canada
Member Since: December 28, 2009
entire network: 121 Posts
KitMaker Network: 25 Posts
Posted: Sunday, March 07, 2010 - 04:20 PM UTC
I built one of these myself, but I'm kind of regretting it now. Well, regret may be the wrong word, but I use the unit very little. Styrene just doesn't seem to cut or grind well, no matter the speed you're using. Too fast and your stuff melts, too slow though and the bits and cutters just chatter on the surface of the styrene. Sanding disks just seem to scratch the surface and leave tool marks, even when using a fine grit. Slitting discs just get gummed up with stryene material. My dremel is a dream for resin, but you don't really need a speed controller for that.

The only real use I think works is when you're intentionally trying to chew up a styrene surface to represent damage and casting textures.
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Connecticut, United States
Member Since: August 15, 2005
entire network: 25 Posts
KitMaker Network: 24 Posts
Posted: Monday, March 08, 2010 - 01:37 PM UTC
I use my speed control all the time usually when drilling holes or cutting styrene I run it fast enough to stop the chuck with my fingers, gives better stop and start control.

Also if you apply bees wax the type they use in sewing or model ship rigging onto the bits and cutters they will bite into the styrene and cut a whole lot easier with less chatter. Same principle as loading up a stone grinding wheel with wax so that the wheel does not clog with the ground material and tends to fall out as the wax heats up.