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ki2401
08-18-2010, 06:21 PM
I'm trying to connect a 5mm motor shaft on a unipolar stepper to .125" square drive shaft.

I was hoping to find some type of mounting hub that would allow me to do this -- anyone seen anything like that?

It's okay to tell me I've just started off on the wrong foot and just get a motor with a square shaft.

Benjamin
08-19-2010, 12:41 PM
Pololu has several universal mounting hubs that might help you accomplish what you're trying to do.

* universal aluminum mounting hub for 3mm shafts (http://www.pololu.com/catalog/product/1079)
* universal aluminum mounting hub for 4mm shafts (http://www.pololu.com/catalog/product/1081)
* universal aluminum mounting hub for 5mm shafts (http://www.pololu.com/catalog/product/1203)
* universal aluminum mounting hub for 6mm shafts (http://www.pololu.com/catalog/product/1083)

- Ben

ki2401
08-19-2010, 02:07 PM
Thanks! I appreciate the suggestion.

Tommy_T
09-26-2010, 05:58 AM
If the motor shaft is square I see no reason why a standard clamp on type flex
coupler wouldn't work. just measure from corner to corner and get at coupler with
that ID size.

not sure I would use it for high torque applications, but should be fine for stepping motors.

Tommy

darkback2
09-26-2010, 10:47 AM
You could always cut a hub using a lathe. If you don't have one check your local community college or skill center. They sometimes like to have jobs for students to do. For the square shaft make 4 set screws. That way you can clamp down on it pretty evenly. If the square shaft is big enough you can drill 4 divots into it so that the set screws have something to sink into.

zoomkat
09-26-2010, 01:43 PM
If the load isn't too high, you might be able to make a little shaft coupling using heat shrink tubing. After it is made, a little super glue might be needed on the round shaft.

jdolecki
09-27-2010, 06:19 AM
For making square holes you need a square broach.

Their expensive.

http://www.mcmaster.com/#square-broaches/=90zqy8

darkback2
09-27-2010, 10:35 AM
Thats why I suggested the four set screws. Drill the hole bigger then the square shaft and then clamp down on it with the 4 set screws...saves a bit of money. You could also cut the shaft in half and mill out a channel in each side and then clamp the two halves together.

ki2401
09-27-2010, 11:27 AM
Everyone, thanks for the helpful suggestions! What I discovered was that the basis for my question was wrong -- I started out combining some components from Phidgets and the unipolar stepper motor available on trossen with some components from VEX -- the vex components / gears all fit the square drive shafts.

Anyway, I ended up just getting gears from McMaster-Carr for my round motor shafts and connecting it to the drive shaft gear to gear.

The heat shrink tubing idea is great -- I'm definitely gonna tuck that one away.

Thanks for the help!

zoomkat
09-27-2010, 02:28 PM
The heat shrink tubing idea is great -- I'm definitely gonna tuck that one away.

When I was a kid, the kits with small motors used a small piece of rubber tubing that was pressed on to the motor shaft and the connected shaft to couple them together. Small vinal tubing used for aquariums might work, or something similar molded from silicone sealant to make a press on coupling.