Re: [CAD_CAM_EDM_DRO] making an ali flexible coupler

Graham Stabler wrote:

>I am building a tiny CNC rotary table for my Proxxon milling machine
>and now have a small 60:1 wormwheel gearbox and a Nema11 stepper to
>turn it. What I now require is a flexible coupler to link the two.
>I could just use some flexible tubing and I could just buy one but I
>thought it might be nice to try and make one.
>
>I have one very small aliminium coupler I got off a DC motor some
>time ago. It has 6 slots cut into it, 3 in one direction and 3 in an
>orthogonal direction through the adapter. This allows it to flex in
>both directions easily. I think I can make these easily, I have nice
>thin diamond wheels and could program the mill to take nice gentle
>cuts at the correct heights and orientations.
>
>I have some larger couplers though that have two spiral cuts through
>the aluminium of the adapter so it is more like a spring in those
>sections. I have been reading about thread milling on the board
>recently but is that possible if the blank was held on the bed at the
>correct angle?
>
>

I think these are normally made by wire EDM. But, I think you could
make a servicable one with a slitting saw. You might want to make it
like a 3-start thread, so it delivers balanced torque. You don't want it
too springy, either. I think you have to already have the rotary table
working to accomplish the helical movement. Using the mill head
straight and parallel to the axis of the coupler would end up with
very wide cuts and narrow metal fingers connecting the two ends.
You might try the tubing as a temporary coupler to make the real
part.

Jon