Adapter for Dremel

When working with high speed rotary tool it is sometimes useful to have a possibility to use tool with shank diameter other than 3.2 mm. Dremel has nice chuck for their machines. In the naive belief that my Asist rotary tool is Dremel compatible I acquired Dremel chuck for my use.


But Dremel uses different thread on the spindle. Thread size for the metal output shaft is .28 X 40 threads per inch, which means thread with diameter 7.112 mm and 0.635mm pitch. But on my high speed rotary tool is M8 x 0.75.

Dremel adapter scheme

So I decide to turn the adapter. Only problem was the inch thread. My mini lathe is capable to turn the threads but (according to instruction manual) only metric threads. But from collection of tooth gears is possible to set up a gear for number of different pitch. I found gear setup for the 0.63281 mm, which yields an acceptable result.

thread turning

After turning the thread into the size, when it was possible to screw the Dremel chuck manually on the first thread I calibrated turned thread. I use grinding paste and using force I turned the chuck to the full length of thread. So it is possible to turn chuck comfortably but without unavailing looseness.

Dremel adapter