I am look for a ah, well, you see I don't quite no what to call it.

The drive mechanism for a stationary lead screw design.
The whole assembly (including gearing) between the stepper
and up to and including the (hopefully anti-backlash)
lead nut.

I don't know what to call it nor do I know where to find it.

Any suggestions for COT equipment of this sort?
Or am I stuck with fabing it up myself?

Thanks

Your'e talking about a rotating nut? A while back, a website for one of the low cost commercial machines (can't remember which) listed a rotating ballnut assembly. The price was around $800-$900, I think. It included the nut, belt drive and motor mount. But I haven't ben able to find it again.

It sounds like you're looking to rotate the nut ("rotating nut" assembly.) I have designed several of these to get longer strokes without ballscrew whip. THK and others make a rotating ballnut assembly with a flange for attaching a pulley and one for anchoring to the thrust bearing to the carriage. They're extremely expensive, you'll probably want to make your own.
Kevin

This is what I figured. I guess it's off to the old drawing board.

What about a source for "accurate" pulleys. I am concerned about the 'true' ratio of the pulleys. I know I can take measurements once I am up and running, and back it out in the software; but I want to be on the money from the get go.

So now my questions turn to...

Sources for pulleys? Belts?
I am looking at ~450oz steppers, so where can I find adapters for the motor shaft to the pulley?