DIY Rotary Tool

[Shashank] has a modest tool collection but is missing a rotary tool. He needed one for a project he was working on but didn’t think that it would get much use after the current project was completed. So instead of buying a rotary tool, he decided to make one to get the job done.

The project started out with a 40mm PVC pipe that would serve a the main body of the tool. Two MDF disks were cut to fit inside the pipe. One was used for mounting an RC vehicle brushless motor and the other was bored out to accept a pair of bearings. The bearings supported a modified pin vise that acts as the chuck for securing rotary tool bits. A 20-amp ESC and a servo tester control the motor’s speed and can get the motor up to 18,000 rpm.

Although this worked for a while, [Shashank] admits it did fall apart after about 20 hours of use. The MDF bearing mounts crumbled, thought to be a result of vibration due to mis-assignment between the motor and pin vise. He suggests using aluminum for the bearing mounts and a flexible coupling to connect the motor to the pin vise. If you’re interested in making your own rotary tool but don’t have any spare motors kicking around,  this 3D printed vacuum-powered rotary tool may be for you.

17 thoughts on “DIY Rotary Tool

  1. Part of having a tool collection is obtaining things that you feel will be useful now and in the future.
    I can buy (I have more than one) a rotary tool for under $15 that does a good enough job. If I used it every day, I’d buy a better one.
    Why would you spend the time building one, sub standard (20 hours MTBF) when it would take less time and probably cost to buy one in most of the western world ?

  2. Why do people try to rationalize hacks? Only needing a rotary tool for one project is not a reason to go through all the trouble of building one. It’s a reason to buy one for ten dollars at Harbor Freight. Just admit it was idle curiosity. (And if it wasn’t idle curiosity, learn the value of your own time.)

  3. While the hacker’s rational may be called in to question by some (hmm, perhaps they live somewhere else where such things are not readily available), I have to admit I’ve thought about something like this as a route to create a cheaper, high-accuracy tool (a lot of the cheap import ones seem to suffer from run-out).

    Now, I’m not sure if I’d use an RC motor as the drive source (running through a thrust bearing to take the load from the tool) or attempt to upgrade an existing device. As I’ve not really looked into either option, it’s interesting to see someone getting reasonable success with an RC motor.

  4. Big Lots has them as well as Wally World for $10 ‘merican day and night. I would have just modified one of those to last more than a day ha. Otherwise I actually like his build as it would act as a nice test ground for modifying one of those. Keep on making things shashank.

  5. Hackaday has featured DIY precision spindles using RC BLDC motors before. Of course the precision aspect needed the builder to invest more effort than a quick hack.
    http://hackaday.com/2014/08/03/brushless-dc-motor-used-for-high-speed-cnc-spindle/
    The only thing that deters me from using an RC BLDC + ESC is they are not designed for the duty cycle that might be encountered in a CNC. It might be just fine if run at maybe 50% of the current rating.

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