Quote:
Originally Posted by luckof13
I found this chart online. I gives recommended rpm for various types of bits and materials. There are also many other charts like this online. I would suggest finding a way to a just the speed depending on what you are drilling. |
That chart is really a rule of thumb. In reality if you have a truely variable speed drive (not one that uses a power transmission with finite speeds like belts and pulleys) you can calculate the proper speed considering the drill type, bit diameter, material characteristics and feed rate (of the the bit into the material). It's the same set of calculations you'd find often used for CNC tools.
Course the real issue is that having PWM to drive the treadmill motor does not mean that the motor remains at a fixed speed when loaded (while drilling for example). To make this really work you need to close a feedback loop like a PID controller. A motor of this power is a more than FIRST speed control can handle.