Adding Rotary Axis to CNC Router - Sanity Check Required.

Guys,

I've just been given a little rotary axis unit, which could be grafted onto my existing 3 axis CNC router without too much trouble. It's a nice little German unit, consisting of a Harmonic Drive AG gearbox, a Rohm 80mm 3-jaw chuck, and a Jenaer stepper motor. It looks like it has never been used.

The question is, just because I have something shiny and it could be done, should I bother?  It would be a neat project, and I'm sure you could make cool things with it, but to be realistic - I can't think of anything I need to make on a rotary axis. I'm not even sure there is a decent hobby priced CADCAM software that will spit out a 4 axis G cade. Mind you, once I had it running, my brother would dream up something he wants made. . . . he's good like that. 

So, am I missing something - is a 4th axis a must-have, and I just don't realise it? 

Cheers, Steve.

Personally I would still keep it. As far as a cheap or free Cad/Cam that does 4 axis I don't know of any.
You could always manually write it into your G-code. Another possibility ( I have seen this  on Laser
engravers ) is to switch out the Y axis stepper cable with the 4th axis after homing and  alignment .
Granted a Router is different then a Laser engraver.

The free version of Fusion 360 does 3+1 and 3+2 but not 4 or 5 axes synchronous.

Ta guys,

It looks like this is not that straightforward. Swapping the axis is a clever idea, it would allow me to bodgy up something if I was desperate. I guess I could always use the unit as a glorified CNC dividing head for indexing, by manually dropping in a bit of G code. 

The other issue is that the gearbox is a 100:1 ratio. Even driving the stepper motor at 1000rpm, it would take 6 seconds for a revolution, which is pretty slow. I suspect that would limit it's suitability for any form of synchronous multi-axis machining.

I think I'll put this on the back-burner for a while, and pull it out again when I'm really bored.

Cheers, Steve.