looking for flexible shaft coupler for 1/2 inch hex

[Bruceb]

Do any of you know where a person could get a flexible shaft coupler for high rpm and 1/2 inch hex shaft?
Or how one would make them without a CNC mill?

[Oblarg]

How much load does the coupler need to take? Is this an encoder coupling (i.e., basically no load) or are you looking to actually transfer motion within a mechanism?

If it's the former, your best bet is to turn the shaft down to 1/4'' round and use an ordinary helical beam coupling.

If the latter, you could possibly hex broach a spider coupling.

[RoboChair]

Originally Posted by Oblarg

If the latter, you could possibly hex broach a spider coupling.

Why not use the surgical tubing coupler method?

[Oblarg]

Originally Posted by RoboChair

Why not use the surgical tubing coupler method?

We used to do this, but found last year that this is prone to introducing a fair bit of noise into the encoder readings. We never quite found out why, though my best guess is some sort of stick-slip effect.

It's not horrible if you use thick tubing and align the shafts well (it gets much, much worse with increasing axial misalignment), but the beam couplers have no such effect and are free from FIRST Choice so we use those now.

[cbale2000]

Originally Posted by Bruceb

Do any of you know where a person could get a flexible shaft coupler for high rpm and 1/2 inch hex shaft?
Or how one would make them without a CNC mill?

How flexible are we talking here? What kind of torque are you trying to transmit?

[Cothron Theiss]

Your chances of finding hex bore flexible shaft couplers are practically zero. But if you can round off the end of your hex shafts to 1/2" or a slightly smaller diameter, you can find flexible couplings.

[Bruceb]

Originally Posted by cbale2000

How flexible are we talking here? What kind of torque are you trying to transmit?

RS-775 pro direct driving 2 inch AM wheel for shooter through a VP planetary 1-1.

[Jon Stratis]

trying to drive a shooter, I wouldn't rely on a flexible coupler - a failure of that part would be pretty rough. I'd drive it through belts or gears instead.

[Oblarg]

Originally Posted by Bruceb

RS-775 pro direct driving 2 inch AM wheel for shooter through a VP planetary 1-1.

I'd use a spider coupling for that. You can hex broach one, or else turn down the end of your shaft.

[cbale2000]

Originally Posted by Bruceb

RS-775 pro direct driving 2 inch AM wheel for shooter through a VP planetary 1-1.

Why not just use a non-flexible coupler? Why does it need to flex?
The average flexible coupler is not really intended for these kinds of load transmissions. You might be able to get away with a universal joint but even that I wouldn't recommend for long term use because of durability and efficiency loss.

[dradel]

A 775 spinning at full boogie is up around 18,000 rpm ! A flex joint may not like the rpm if things aren't ballenced.

[Bruceb]

I have a non flex coupler on there now it it vibrates a lot. That is why I was looking for a flex coupler of some kind. Maybe I will just cushion mount the VP and motor.
Will that vibration have an effect on the encoder?

[Cothron Theiss]

Originally Posted by Bruceb

I have a non flex coupler on there now it it vibrates a lot. That is why I was looking for a flex coupler of some kind. Maybe I will just cushion mount the VP and motor.
Will that vibration have an effect on the encoder?

If vibration is your concern, a flexible coupler won't fix it. That's a product of the system design as a whole. You need to make sure everything is aligned properly, nothing's too out of balance, and all your motion is smooth and steady.

[yarden.saa]

We had last year 775Pro on VP gearbox 3:1 direct drive a hex shaft with vex hex shaft coupler with no problem of vibrations. You are probably going too fast, I don't think you need 18000 rpm for a shooter.

[cbale2000]

Originally Posted by Bruceb

I have a non flex coupler on there now it it vibrates a lot. That is why I was looking for a flex coupler of some kind. Maybe I will just cushion mount the VP and motor.
Will that vibration have an effect on the encoder?

If you're using a versa-planetary anyways, why not just use a versaplanetary encoder?