Quote Originally Posted by JohnHaine View Post
Well, I'm still bemused. If it's the cutter that stalls the spindle then it has to take all the momentum of the spindle to stop it so the instantaneous torque on the cutter must be much larger than the motor torque. As I said The motor hasn't stalled any time I've broken a cutter. Anyway it will be good to hear of your experience with the system - will you be doing some controlled experiments?
It's only a 1.5kW motor and so once the cutter is clogged with aluminium it turns into a cylinder being pushed through the material as it is not longer cutting. This brings the motor to a halt fairly quickly but the axes keep moving and so the end mill breaks. The inertia of these Chinese WC motors is pretty small as the rotating core is quite small in diameter. Tends to happen in thin materials as they are almost pure aluminium, not a high alloy content, although cutting 6061 dry can have the same effect but usually a lot less often. Mist or flood cooling helps significantly. I'll use the system and see how it performs over time, rather than specific experiments. The few test runs I've carried out (some were in the video) all work OK. My main concern is how the PLA will perform over time with heat build up - it is only a friction fit so it could slide down, same thing with the sensor disc.