Brushless DC Motor – CNC High Speed Spindle

This build was detailed on mycncuk. The brushless motor has a 8mm shaft which was removed and directly replaced with an Er16 collet chuck with 8mm straight shank. An aluminium bearing block was built and mounted at the front of the outrunner motor support and maintain the spindle alignment.

ER16 chuck with 8mm straight shank
Brushless DC outrunner motor with 8mm shaft
ESC 3phase driver is Sky 100A
Speed controller is a servo tester –
ATX supply using 12v rail.

It spins damn fast and with seemingly enough torque… the proof will be in the pudding!

Warning… sound is stupidly high which is nuts because it is less than half noise of a dremel on full, the camera just captures it for some reason.

Part 2….

Updating this thread as I`ve not had much time to do so recently.

I stripped and rebuilt the spindle and while doing so, I took some pictures:

Here are all the bits. You`ll notice the surface marks where the bearings were skipping on the previous build due to not enough tension and slight misalignment. I hope this is now stopped!?
You can see the thust bearing on the shaft up near the head of the chuck.

The bearings are separated by a number of washers which will compress to apply tension to the bearings.

Bottom half of the motor is screwed up:

And the bell slid on the shaft with a grub screw tightening this up. There is now a flat milled onto the shaft:

It is working well so far. I`d love to know how it would perform as a tool holder grinding spindle on the lathe!

According the my hall effect sensor and Mach3 – I can get 10,100rpm max speed.



  1. Hello I have had the same thought as you and went for one of these motors. I was wandering if you could post more details of how you are controlling it through Mach3? I also have one with inbuilt encoder that I am hoping mach3 will be able to rigid tap with.
    Kind Regards

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