Hi Mark,

Sorry this thread is splitting in two. Referring back to your earlier reply, 80A S/C is OK, and for £15 is probably the low voltage type so don't run it at the 37V (12V is OK). Servo tester is OK and at some point I expect this could be speed controlled from the PC since there is a pot behind the dial. Not done speed control from a PC myself, but plenty of experts on here who could help . . .

I only use outrunners, so don't know about the inrunners or high Kv motors you are considering (from helis and ducted fan models). Nice idea about the engraver using the motor shaft.

Watch out for the heat buildup since these motors are all normally in the airflow. Especially if you go down Irving's route and go for the full 1700W. Some inrunners have finned sleeves which you can buy and fit over the outside of the can. For outrunners you might be able to fix a fan to the outer case, since this rotates, and it will blow air down through the holes into the windings. Bit of noise i'm afraid, so you'll have to see how it goes.
Wonder if you bolted a prop adapter on the back face and added a very small prop, instead of a fan. Mind your fingers, or add a guard if you do!