Need Help!- Best Coupler Type?

[AssassinXCV]

Hello, im in need of some shaft couplers to couple my 1/4" axis threads to some NEMA 23 3amp Stepper Motors.

i've found some but i dont know which one would be best for my uses.

I'm making a cnc machine out of laminated plywood using these plans:

How to make a mini milling machine- manual or CNC!



Here are a few i've seen on Ebay for around $5 each:







Anyone with experience or knowledge of which one's are better, then please respond with your instight. Thanks

[doorknob]

The top one (and maybe the bottom one also) looks like it gets tightened to the motor shaft by pinching the entire shaft as you screw in the setscrew. The setscrew is offset from the center of the shaft (because the setscrew does not contact the shaft). It should work either with a completely round shaft or with one that has a "flat" in it.

The one used in the middle photo looks like the setscrew is centered on the shaft, and it gets tightened down until it contacts the shaft directly - unless your motor shaft has a flat in it, tightening a setscrew directly onto the shaft would seem to be prone to slippage. Even though it looks like there are two setscrews per shaft (which would provide better holding power if you have a round shaft than a single setscrew would provide), I'd prefer one setscrew with a flat to two on a round shaft.

So, IMHO the top and bottom ones are better, but the center one should work fine if your motor shaft has a flat (as long as the length of the setscrew is long enough to contact the flat while still having a sufficient number of threads engaged in the coupler body).

[AssassinXCV]

okay thanks. i dont have any flat part on my motors, and with the grinding equipment i do have, it will just damage the motor. so having the couplers that tighen against the shaft will give the best hold.

i have flat spots on the threaded rod, (since i was going to make my own couplers) but i found that the effort and the final product wouldnt be as good at manufactured couplers.

i guess i'll go out and buy some new threaded rod, they're pretty cheap.

Just one thing, is there any possiblility that the squeeze coupler will slip on the shaft? maybe if it had some sort of coating it would hold it better.

anyways, i'll go for the one that squeezes around the shaft.

...and looking at the pictures again, it seems that the top and bottom pictures are the same style... just different angles

[dustin1706]

The dumpster CNC couplers seem pretty popular. Not sure what thread your axis screws are, but if you click on "clamp on couplers" they have ones that go from a 1/4 shaft to 1/4-20, 1/4 acme, and just a straight .25"" bore.
dumpsterCNC - anti-backlash solutions for home and industrial linear motion

Cool looking little mill BTW!

[AssassinXCV]

thanks for the help everyone. I feel that the Clamp on Alluminum couplers from my post will work best.

Hope to be on here more often once i get my machine up and running; not even finished my first 3axis and i'm already drawing up plans for a 5 axis out of plywood.

Originally Posted by dustin1706 Cool looking little mill BTW!

Thanks, i was so happy when i found those plans, i can't wait to finish it and to start making stuff with it. First year in college and all my friends dont believe that it will work.. i sure hope i will prove them wrong

My machine looks just like that... only in many pieces and not complete... YET!