13.35mm ~ 0.525in (maybe 0.5 plus 0.025 powdercoating)
19.93mm ~ 0.666in (that explains alot)
Rough it out to 0.53in dia and 0.67in distance. With the insulation on these clamps, or vibe dampening rubber there is some wiggle room but probably not much.
J&M Products has a very nice catalog with these measurements and more listed (to 3 decimal places! +/-0.015
PN 44LC1-? (D=0.525) E=0.525/2=0.2625+0.409
NEED E-measurement w/
... custom order?
There is also AS4149; they have a different way of coming together at the fastener end, which would not be good in this application. I think the LC Series is good.
J&M Products uses a variety of materials in these things, all listed in the catalog. Anything from Alloy Steel to Ti, with cushions (insulation) made from chloroprene to silicone (even fiberglass). But what is the best materials for this application? Maybe asking J&M is the best solution?
ps - thanks for the vote of confidence Loaded?