looking for flexible shaft coupler for 1/2 inch hex

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 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.

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.

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

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.

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

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.

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

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.

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.

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.

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.

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

no probably not all that but we are spinning a 2 inch wheel

because the encoder made for the RS-775 pro is much smaller and I have heard good things about it.

Ok, so I think there are a few things you should look at to try and fix the problems in the design rather than patch over them. You should have some reduction coming off of an RS-775. You already have the VersaPlanetary in there, why not change it to an actual reduction? This will vastly improve the accuracy and consistency of your shot anyways. As for the encoder, if you already have the encoder set up for the RS-775, that’s fine. But you can also use the VersaPlanetary integrated encoder. It works very well also.

What motor and encoder specifically are you trying to use? Perhaps provide links?

To my knowledge there is no such motor as an “RS-775 Pro”; there is an “RS-775” and a “775 Pro” but these are very different things.

For a rotary encoder, I suggest you turn the end of the Hex shaft down to ~ 1/4" and use a piece of 1/4" fuel hose, ~ 1 1/4" in length and use a couple of flat spring clamps to clamp the ends. Then carefully align it. The fuel hose and flat clamps are standard lawnmower items.

The harder mechanical flex couplers transmit a lot of vibration to the encoder, and can cause pre-mature failure. The company, that I worked for introduced a flex coupler then discontinued their use. And, went back to the fuel hose.