Flexable couplers

Im in the market for a flex coupler, and noticed there are 2 styles at 3DPC.

The all metal

I also found this coupler, is it just the finish thats different between the 2 metal versions?

And the scilicone flex coupler

So cost aside, does anyone have a preference of one over the other? Why? Or why not?

I suppose it depends on what your using it for and how “flexible” it needs to be. I used candidate #2 when I made my laser engraver from scratch.

Candidate #1 appears to be identical to #2. They both employ a spiral cut that essentially turns them into thick springs that allow flexing movements perpendicular to the shaft, but relatively little compression/expansion and no noticeable relative rotation.

Candidate #3 appears to allow more flexibility?? Maybe it transmits less sound?? I have no experience with them.

As is all too common, 3DPCs descriptions run the gamut from basically useless to non-existent.

It’s pathetic when you have to search other company’s web sites to get more info on 3DPCs product selections. Looking on Amazon, some of these models are described as having electrical insulation properties (ie. the nylon completely separates the two halves) but other than providing isolation from static electricity, I’m hard pressed to think of where this would be useful. It’s also described on Amazon as providing some vibration damping. There are stepper motor mounts that do something similar: separate the stepper from the frame with a nylon cushion, but really, it’s not the steppers that are causing the noise, it’s the timing of the signals that drive it, so if noise is what you want to get rid of, you’d be better off killing it at the source by using silent stepper motor drivers.

So, in the end, I can, and did, and would again, go with candidate #2 but I can’t give you a really good reason why in relation to the others.

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3rd option is a lovejoy style there are 2 hubs and a rubber insert. The pieces all come apart so the driven end and drive end have to be constrained a diferent way to keep the parts from separating. on the other 2 I suspect one is steel.

Electrically isolating motors is a huge deal on some machines, especially if large currents are being switched nearby. The low voltage communication is a big problem with controls and they only overcame it by shielding all the wire, optical isolators on circuits and things. All this small voltage small current stuff is destroyed by static electricity. even a carpet shock can be 20 000 volts. And of course, vibrations are just bad all around.

I try and use the silicone style ones, I usually use the more rigid ones on CNC machines.