No videos yet, but I do have an update. During bench testing I found that the motor electronic speed controller was getting pretty warm at mid-range speeds. It was fine when flat out, but would get too hot to touch after 20 to 30 seconds at mid-range. I tried fitting a heatsink to it, but there was clearly something not quite right.

After enquiring on an electric vehicle forum (my interest in CNC is to build EV parts) a couple of the more experienced RC model motor guys suggested I needed to derate the controller to a greater degree if it was to deliver higher power at mid-speed. This makes sense, as a model aircraft propeller absorbs power in proportion to the cube of it's rpm, so the controller wouldn't be optimised for running at high currents at part throttle.

I thought I'd been conservative in buying a 40 amp controller when the most my power supply can put out is 30 amps, but it seems that I was wrong. I've switched to a spare 120 amp controller I have for another project and the performance has been transformed. Not only does the controller not get warm, but the speed control is very smooth indeed and the motor starts from a standstill very well. The other plus point is that the motor no-load current has reduced by about 50%, which goes to show how inefficient the original controller was.

Although the motor whines a bit at max speed (around 16,000 rpm) it's not excessively loud. I've been testing it in my study and have so far not elicited any complaints from SWMBO, which would not be the case if I fired up a router in here!

I've still got a bit of fettling to do, including reducing the drag on the bottom bearing, but all told I'm exceptionally pleased with the outcome so far. It looks like it will meet my design goals of being compact, relatively quiet, affordable and fairly accurate.

Jeremy