Sunday, September 2, 2018

5C Lathe Part I: Motor Mount


I'm putting together a new manual desktop lathe to replace the one I put together two years ago. The old one has been awesome, despite its weaknesses and size it is the most useful tool I have ever had.

The new one is made with light production in mind, for making drawer pulls and hand tool parts. It has a 5C spindle, quick-change tool post, and slots for mounting five or more tools in a gang arrangement.


Above was boring out the hole for the motor using a fly cutter. I adjusted the cutter with my most precise hammer and ended up with a darn accurate bore, a snug slip fit over the motor. :) The motor is a 450 w brushless DC motor, pretty spicy for a motor that's smaller than the lathe spindle itself...


I wanted the fit to be close so that the pinch bolt wouldn't have to stress the aluminum much to clamp it (it does clamp easily). The outer edge of the plate is pretty sloppy though; I got tired of filing the gummy aluminum. A mill or router would have been nice for that.


I roughed out the plate shape with a wax-lubed coping saw, which was actually pretty quick. The 18" frame saw also cuts through it plenty fast. I made the plate to fit the vee belt I had on hand (standard Taig lathe belt), after I machined both pulleys. It pivots on the bottom mounting screw and locks with the screw on the top to tension the belt. I erred on the long side for the slot travel since the belt is heavily used.


Approx 1:6.5 reduction. Small pulley machined of steel and secured to shaft with setscrew bearing on flat portion. Also managed to bore a tight slip fit on the motor shaft with a little honed carbide boring bar.


Used steel shaft collar to mate the plywood pulley to the spindle--I often grab the pulley and rotate by hand to tap holes and do other high-torque stuff. Setscrew just seems hackish for this.


Stay posted for the base, tooling, electronics, and maybe even an electronic leadscrew-