I’m almost done with the headstock!
My last post showed the headstock using a fan motor and a cordless drill chuck joined with a shaft coupler to be possible. My next step was to make it a bit more practical to build, by designing in some tolerances.
The people who designed this fan motor were both very practical and very cheap. Of course, trying to make profitable margins on a $6 motor imported from China and sold by Wal-Mart would necessitate such a design philosophy.
The motor armature was restrained inside the motor body by front and rear yokes supporting the armature’s shaft. One thing that surprised me, however, was noticing as I broke the glue seal on the yoke nuts that the yoke bolts on either side of the motor seemed to be loose on purpose. Too tight, and the armature would not move freely enough to spin when current was applied. The only thing preventing the yoke bolts from shaking loose was the glue on the nuts.
I had to remove the armature to thread its shaft, so of course I had to break the glue seal. When I reassembled the motor and tested it I noticed the nuts slowly spinning off the bolts due to unavoidable armature vibration. I didn’t want to use glue as that would cause later maintenance problems, so instead I used a lock washer sandwhiched by a pair of nuts. The nut toward the motor would define the tolerance for armature motion, the outer nut and lock washer would lock the inner nut in place.
This setup would restore the built-in design tolerances necessary for the fan motor to operate in the first place.
Original fan used loose yoke bolts whose nuts were locked using glue, we use a hardware sandwhich instead.
In my last post I had resolved to provide a shock-absorber system to dampen unavoidable runout caused by differences in the design between the cordless drill chuck shaft, the fan motor shafts, and the best shaft coupler available for minimum cost and effort.
This system was not hard to define. I simply created a table to hold the motor above the base, using springs restrained by carriage bolts to suspend the table.
Close up of lathe motor spring suspension system to compensate for runout
The base of headstock also forms the base of the motor’s suspension system. The nuts at the base of the headstock keep the assembly together, and also can be used to adjust the tension of the suspension springs to optimize dampening of vibrations due to the shaft runout inherent in the design.
Base of motor's spring suspension system
Despite the problems I have had to confront, the result is not necessarily a poor design for a headstock. This headstock is, instead, a practical design based on available parts and materials on a very limited budget which can deliver adequate results for very modest needs:
Simple lathing setup involving the new headstock
To demonstrate this I simply held a carbide cutter against a rotating piece of wood that I had
mounted into the chuck using a screw. Too much pressure caused the rotation to stop, so
I quickly backed off. With a few minutes and some patience the wood had gotten a groove
shaped into it.
Results of simple lathing using the new headstock
Which Is What We Want
