Diy Brushless Spindle

[booski]

Hi there,

First post here and entirely new.

I just wished to contribute something. For my honours project for my degree, I made a desktop CNC machine.

Part of this project was to produce a simple spindle. To drive it I used a brushless motor, a small thing.

As you know, to control a brushless motor speed you need a servo tester. The trouble is, when you switch a brushless ESC on, you need to wait about 7/8 seconds with the servo tester at full off while the ESC initialises before turning up to the required speed.

Well, I designed my own speed controller using a simple PIC micro controller and program. It's designed as such so that it powers off the ESC's own servo supply. When power is applied to the ESC, the controller starts off at zero ignoring the speed dial for 8 seconds while the ESC initialises. Afterwards, the controller reads the dial and spins up the motor.

It makes the whole thing automatic and requires no manual intervention. Simply a delay from the control software on the host computer to accommodate for the ESC initialisation.

I'm curious whether there's any interest in this sort of thing as more brushless spindles come about? I've not seen anything like it before.

[Jonathan]

I'm curious whether there's any interest in this sort of thing as more brushless spindles come about? I've not seen anything like it before.

Yes I should think there is, at least for Mach 3 users. A long time ago I made a simple circuit using a PIC12F683 to interface between the parallel port PWM output and a standard ESC. However I didn't use it for long since, in addition to getting a standard spindle, I switched to LinuxCNC for which someone has already written the code to make the parallel port output the correct PWM signal for an ESC.

On a related topic, I recently put the motor I originally made into a spindle on to my Mum's bike. For that I used one of the electric bike speed controllers from eBay and added hall-effect sensors to the motor. As one would expect, it's far better than the sensorless controllers, especially at low speed, so if I was to make another brushless motor spindle I'd definitely control it with a similar controller:

48V/600W brushless controller for E - bike & scooter | eBay

They're also programmable, so you can set the current limit among other things, which could be useful for this application. I'll post a picture when I've got it off the other computer...