DIY Machining center development

The Arduino board, that we know from many multicopter projects, is used to control this 4th axis. This is a video posted by Steve Simpson on YouTube. This is the same 4th axis I have for the BF20 mill, and it’s very nice to see how Steve continue to expand the possibilities.

“here is the long needed custom 4th axis motor controller. Designed specifically to take full advantage of the unique capabilities of the ‘mini machinign center’; which is a normal mill fitted with one of my 4th axis”

4th axis for the BF20 Mill

I have ordered a 4th axis from Steve Simpson. I first became aware of the product when I saw it in a forum post at It’s a versatile unit that can be both 4th axis and lathe. Mine is ready in a couple of weeks, and I can’t wait to test it.

The product have gone through several design changes since I first saw it on YouTube. It has been a fun process to follow, and the result of the evolution is amazing. I went for a heavy duty version with 2 step belt reduction and pneumatic brake. Max RPM in lathe mode will be around 3500 with 1:1 ratio in 2nd gear. I have decided to use a Yaskawa 750W AC servo in the Sigma II range. The servo setup seems easy enough, but I have only tested it with the RS232 interface. As a 4th axis it will be controlled with Mach3 and position control with step and direction signals from a computer.

These machines are hand made in batches, so you have to contact Steve for details. His website is: You can also check out his YouTube channel for more videos.

Expect a follow up when my 4th axis arrives!