Oldham Couplings

I'd consider it better to use dissimilar metals in contact with one another. eg steel-brass-steel.

Bob

Yes, the parts slide against each other. Not a lot, but they do slide.

As they only slide a little bit, and it's roughly always the same bits they slide on, they might develop lands, ridges, or whatnot at the ends of the travel.

So I'd try and use materials with different hardnesses - one really hard, one as soft as practicable - if at all possible.

The soft part should probably be in the middle, and slightly shorter than the outer bits along the direction of slide, for best results. The way the ends of the short soft part will be worn down by the hard part, and no ridges should form.

Hope that's clear,

-- Peter Fairbrother

Yes, that's very clear, and thank-you both, especially for the caveat on ridges forming