[bassman2914]

I don't know what it's called but it has a pretty distinct look with some weird connector in the middle. I found it here (CNC Stepper Motor and Components, Keling Technology Inc, USA) and it's 1/4 the price of the same looking one on mcmaster and it says it's zero backlash and made for servomotors so I'm interested. Problem is I don't have a clue how it works so I don't know if i trust the claim(considering mcmasters also calls the helical couplings zero backlash and we all know that's not true). They're the cheapest zero/anti-backlash couplings I've found so I hope I hear good things about them. Any guesses on allowed misalignment?? don't need much, just some breathing room.

[Al_The_Man]

It looks to me to be a flexible disc version, each end of the coupling is fixed to a flexible disc in the centre, this allows flex with zero backlash.
Al.

[jsheerin]

To expand, the disc is very stiff in the plane of the disc, so it transfers torque well. However because it's thin, it can easily bend out of plane and thus allow some misalignment of the shafts.

[vegipete]

Looks like it will allow a few degrees of angular misalignment, but no radial misalignment. A double version, or perhaps two singles tight together with a short stub of shafting in the center would allow some radial misalignment (and double the angular misalignment.)

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As an exercise in creativity, I might try make one for fun.