Worm Drive Experiment

This article and video contributed by Ron Walters

I wanted a worm drive for one of my projects. I felt reasonably certain I could use a wood auger brace drill bit as the worm but it would require a few modifications.

The wood screw, spurs and cutting edge at the end of the bit would need to be removed as well as the first flight of the auger, which had a shorter pitch. I ground away the bulk of the unwanted material on the bench grinder. The first flight was removed so the remainder of the auger would be of consistent pitch. With the bit held at one end and being turned in my small lathe, I hand held a Dremel Tool (with a cutoff blade) and very gradually ground the end of the bit to a more consistent diameter. Both ends of the auger will be centered and epoxied inside a wood dowel so the auger (worm) will run true when held between a pair of wood pillow blocks.

The center shaft and inside areas of the flutes of the wood auger bit are not of consistent form. I saw making a helical gear as being a bit problematic for this purpose and decided to use a standard spur gear modified to run as a worm wheel. Since this would be used in a low speed low torque application, this simplified version of the worm wheel should be quite adequate.