Cheap Diy Foot Speed Control for Dremel or Other Tools




i have a b&d rtx rotary tool and love using it but the switch and speed control where so far apart i decided to make a foot speed controller out of a broken sewing machine foot switch.
the good thing is i can set my top speed limit with the controller on the rotary tool so its like a set and forget, also i don't have to turn it off any more unless in changing bits since on my model you have to have the switch off to change a bit.

parts needed are.
1x singer or whatever brand sewing machine foot switch.
1x extension cord.
1x soldering iron.
1x roll solder.
2x 2in pieces of heat shrink.
wire cutters and screwdriver.

total cost was $4 dollars.

Step 1: Removing the Cables

after you remove the box covering the cables you need to only cut the 2 wires going to the motor.

Step 2: After Cutting Strip the Ends and Do the Same With Your Extension Cord.

well i have my wires cut on the cord and foot switch so slide your heat shrink over each wire and solder the cord with the outlets to your foot switch.
i used a cheap torch to shrink my heat shrink.

Step 3: After All Is Together Test

after i got it all together i tested it out and it works better than i thought, the low speed on my tool is 15k rpm but with the switch i can go a lot slower than that and max is 30k rpm.

Step 4: Enclosure Box

i have no enclosure boxes so i was trying to figure out what to use.
well i found a old chew can laying around, (use what you want) and i think it looks ok.
ps; im not a chewer.



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    8 Discussions


    Reply 2 years ago

    good question I was wondering the exact same thing. Unclear on the wiring without a schematic. Doesn't show exactly which wires go to what. Since we are using a sewing machine foot pedal it's not even the same thing.


    2 years ago

    I'm not seeing how you have this wired, you have 1 wire that has a wire nut on the end? Is that 2 wires connected together or is that just 1 lone unused wire? Very unclear directions, Is this dangerous to use this in this way? What does the schematic look like for this wiring?

    I have 2 old sewing machine foot pedals and they both have a 3 pin plug going to the sewing machine. 2 wires from the 120v AC outlet and 2 wires go to the foot pedal, 4 wires turn into 3 inside the plug. Which wires are going to what? I imagine 1 wire is being controlled and 1 is going straight to the 120 VAC, so why is there a 3rd wire connection in that plug? Why does your motor only have 2 wires going to it but I have 3 wires that plug into the machine? Are sewing machine motors controlled differently, what keeps the motor or pedal from burning up while reducing speed? Most Variable speed motors have 3 wires or are controlled by changing the frequency of the AC input power. Simply adding resistance in line will destroy a motor or the controller due to heat build up or brushes burn up from the voltage drops.I thought that input voltage must be maintained while field voltage (the current that produces the magnetic field around the outside of the motor) is varied. Otherwise a motor will just draw power in excess since P=IxE Where P=Power (Watts) I=Intensity (Amps) E=Electricity (Voltage) P is maintained at all times so decreasing any of the others will result in an opposite increase in the other to keep P at working levels. Dropping voltage will increase current draw and burns up brushes and windings, unless there's a 3rd power controller wire to control the magnetic field, or a variable speed controller that will change the frequency in Hertz to change the field while maintaining the input voltage. DC motors work slightly different and may not be a problem, but the pedal may still burn up due to added resistance.

    Maybe your motor is DC but that doesn't explain how your wife can control her mixer or blender, maybe it's not being used for a very long period of time? I know I will run my tool for an hour straight without turning if off ever. It's running for 3 hours sometimes with only 15 or 20 seconds time off every 20 minutes. Never gets hot and I have the original brushes still in it, it's not a Dremel brand, it's made by "Allcraft" (rotary tool 8k-30kRPM) I believe it's much better since both my Dremels quit working after only very little use, neither was ran full speed and neither was used for over 30 minutes at a time, both were junk within 2 years, maybe 100 hours of very light use.

    I've owned the Allcraft for 10 years now without any problems with heavy use, I just want to be able to increase speed while I'm pressing down hard on certain areas while polishing. I have the wand extension, so the motor is hanging off to the side and changing speed while working is impossible.

    Do you think they quit making the speed controllers because the were burning up the motors?
    Or maybe the pedals got hot and caught fire?


    6 years ago on Introduction

    Good idea, can we use it with hitachi electrical drill machine?


    7 years ago on Introduction

    Great idea my friend. I'm going to hit up the thrift store tomorrow and try to nab an old sewing machine pedal. Solid instructable. Thanks.

    1 reply

    Reply 7 years ago on Introduction

    Thrift store is a great place for cheap parts, we also have a pawn shoppe here that sells as is stuff love it.


    7 years ago on Introduction

    Thanks for posting this. I've been wanting to do this for my scroll saw, and now I know how!

    1 reply