eBay/Chinese rotary 4th axis?

Hi guys,

Has anyone adapted one of the cheap Chinese 4th axis units to an SO3?
I see these all over eBay for about $130 including chuck and stepper, seems crazy cheap.

I understand that the stock controller does not support a 4th axis, but
it should be possible with a Geckodrive or other controller…?
Anyone done this yet? Any issues with Z clearance, etc.?

I am considering buying an SO3 and one possible application would be for engraving
the outer surface of a small brass cylinder (banjo tuner) with a shallow decorative design.


I have been actively looking for 4th axis and or a rotary table for an up coming (really cool) project. I see two major problems: Height and controller.

I have been looking into using X or Y to control the 4th axis since I won’t be using all 4 at the same time.

But since my project only needs an indexer, I have been looking more towards a 5C indexer or rotary table, but again, I am hitting a height problem, so I continue to look.

Hi Richard,

Yes, I though Z clearance might be an issue with these little rotary axes.
I was thinking to maybe mill a through-hole in my table that could serve to both index the 4th axis into place repeatably, and also gain a little bit of vertical clearance. Then, machine a table insert to fill it in when I’m not using the 4th.

I have about 300 brass banjo tuners (3/4" cylindrical brass gearbox) that I’m considering engraving with a simple decorative design.
It’s enough parts that I could justify some tooling expense. It’s either that, or else invest in a knurling-style tool to roll a design in on the manual lathe. Decisions, decisions…

I’ve been considering something along these lines for a while — since I need to do fairly narrow stuff, my plan was to bolt it to the front of the machine, and dismount it at need.

There have been a couple of people who’ve done this for the SO1/2: