There are plenty of DIY Dremel-style rotary tool ideas available on the internet but I couldn’t find anything that was powerful enough or usable in the long term, while looking good! So I decided to design and make my own 3d Printed Dremel-style rotary tool.

Though I had recently purchased a professional 160W rotary tool, but I now mostly use my own rotary tool as it is compact, light, yet powerful enough for 90% of the things I have to do and much lower noise.

Safety Warning: Power tools should be handled carefully with the appropriate safety equipment. Safety Equipment, especially face mask, will also be required during this build as it involves sanding and painting the parts. I cannot be held responsible for any injuries, damages or losses caused during this build or by the rotary tool. Go ahead at your own risk :)

Step 1: The Design

After starting from crude sketches and going through several iterations, I used Fusion 360 for the 3d CAD model. With some more back and forth iterations, I reached a design which was ergonomic and could also fit in the electronics.

The front part has a groove for giving more control while doing detailed, precise work. It has a snap fit which makes it detachable for changing tool bits.

The rest of the casing is made up of 2 parts stuck together using adhesive and holds the motor and pcb with vent holes for cooling.

Step 2: Parts Required

3d Printed Parts: Total 3, I got mine printed at 3d Hubs with PLA at 200 microns.
12V DC Motor: Listed as 6000 rpm, RS-550S Motor. Diameter~37mm
PWM DC Motor Controller 3A
Mini Chuck/Collet Set for 3.17mm Shaft
Adhesive
Wires
Black Rubberized Automotive Paint(Optional)- I used one from Rust-Oleum
12V Power Supply , Atleast 5A current
Rotary tool bits

Step 3: Assembly

1) Sanding and Finishing

Sand and Finish the parts to get the right fit and remove irregularities. Especially the snap fit at the front cover. You could also temporarily connect the motor to a 12V battery and chuck, and use the tool bit for sanding.

Don’t forget to wear appropriate safety equipment.

2) Rubberized Paint

After sanding and finishing, Paint the lower-part with Black Rubber Automotive Paint for a nice grip and aesthetics. I did 4 coats for a nice soft-touch feel. Paint outside in open area and use safety gear.

3) Connecting the wires

Solder the wires to motor terminals, the other ends go to the ‘Motor +/-’ terminals on the PWM controller circuit board.

Pass 2 wires through the smaller hole at the end of the ‘lower-part’ and through the small triangular hook as shown in image. Then connect one end to the ‘Power +/-’ terminals on the circuit board and other end to a 12V power supply.

Turn on the 12V supply to ensure that the motor turns counter-clockwise. If not, switch the wires going into ‘Motor +/-’ terminals.

4) Putting Everything Together

Using 2 machine screws provided with the motor(usually M3 screws), secure the motor to the front side of the casing. Remove the potentiometer cap from the PWM controller and insert it through the hole at the end of the lower casing.

Using a minimum of two M3 self tapping screws, secure the PWM controller board to the lower casing.

Tuck the motor wires in, and stick the lower casing to the other half casing by applying adhesive at the edges.

Insert the chuck on the motor shaft and secure it. Snap on the front plastic cover. Put the potentiometer cap back on.

Step 4: Ready to GO!!

Cut, Engrave, Sand, Polish, Drill many materials including most Plastics, Woods, relatively Soft Metals like Aluminium. Great and useful DIY project if you own a 3d printer.

Smaller tool bits fit in directly, but for larger bits either you may sand the opening hole of the front cover or not use the front cover.

The front cover is mostly for holding the rotary tool closer to the tool bits to give more control.

So far, the rotary tool has been working great. Making the 12V wire removable, using screws instead of adhesive are some possible improvements I’m thinking about. Let me know any suggestions for the next version in the comments below and I’ll try to make them happen!