Team Darklight - Featherweight Axe/Hammer diary

[Eventorizon]

The Scooter motor is the standard 'go to' for a simple FW axe, 300-350W normally, and 500W if you are crazy. They are large and heavy but produce a lot of torque for very little power.

Check out Hatchet for a good example of a FW axe. I believe its a 5:1 ratio in 3/8in chain. We use a 4:1 ratio on our axe bot Matock but rather than a chain its a HTD T5 timing pulley profile.

Brushless axes are a thing, but they require a lot of gearing and a high end ESC to cope with short, high current loads that axes need to fire. They are also not that much more effective in combat, though they do leave slightly deeper dents.

[Maxamuslead]

also I remember reading somewhere that the weight of the axe head plays a large part in how much energy is transferred in the hit

[adamclark]

Is not an ESC overkill? Is there anywhere a 3 phase 120 phase driver that just applies max power to a brushless motor?

[R9000]

This is how I understand it (and feel free to correct me anyone who's an expert at this): The thing with brushless motors is, you have to know where the rotor is in order to give it max power. To figure out where the rotor is, you need an ESC. This is where the low startup torque situation comes in. In order to find the position of the rotor on a sensorless motor, brushless ESCs use back-EMF that's generated when the motor is spinning. But when the motor's at a standstill or moving very slowly, there's barely any back-EMF to measure, so the ESC has to do a lot of 'guesstimating'. So until the motor's spinning fast enough, you can't give it max power, hence the low startup torque.