5mm - 1/4-20 coupler?

[nx13688]

I am designing a desktop router and am looking for a coupler to attach a 5mm motor shaft to a 1/4-20 threaded rod leadscrew. Rigid is OK, flexible would be great, and of course, the cheaper the better. It would be an easy enough thing to make a rigid one, but no sense reinventing the wheel if there's an off-the-shelf solution.

EDIT: OK, I see that DumpsterCNC has a 1/4-20 coupler with a 5mm bore, so that's an option, but a little more $$ than I hoped for.

[Andre' B]

Originally Posted by nx13688 the cheaper the better.

A short length of rubber hose and two clamps.

[nx13688]

Yeah, that's the route I'll probably go first. I originally dismissed the idea due to the difference in shaft size. But I remembered my Solsylva has tubing connecting 1/4" motor shafts and 5/16" leadscrews, no problem.

[johnmac]

The nylon thread hose and good quality hose clamps work OK. A flat spot on the shaft helps prevent slipping. The nylon reinforcing helps prevent the coupler from twisting.

One thing I have learned from experience is that 1/4x20 threaded rod will make the machine's top speed way too slow. Yes, I built one like that. At this point, it will be a lot of work to change it.

The stepper motors produce the most power at slower speeds. As they speed up they loose power to the point they will stall.

If I were going to go that route again, I would get some 1/2x10 Acme rod from Enco and some anti-backlash nuts from Dumpster CNC. Using a bench grinder with a dressed stone carefully grind the threads off, down to the minor diameter. Then, if needed, drill out some of the inner plastic or rubber from the hose used for the coupler.

Even better yet would be 1/2x10 2 start Acme rod. That would give you 5 turns per inch. With half stepping, this would give good resolution and speed.


John