These parts were salvaged from a special mechanical calibration rig. I don't see anything that looks like that in McMaster-Carr, but perhaps I don't know where to look.

The aluminum part is probably custom but the rod (300-series stainless steel) and the plastic (acetal, I think) threaded part with the brass handle look like standard parts. The aluminum part has an internal thread so the depth of the plastic part can be adjusted by screwing it in or out. The plastic part has a conical lead-in and a bore that fits the stainless steel rod with some play. I believe it acted as a pivot with springs to take out the play.

enter image description here

  • $\begingroup$ Could you describe more about this mechanical rig ? What was it used to calibrate? And which parts do you want a name for? All of them? $\endgroup$ Dec 22, 2019 at 11:08
  • $\begingroup$ This part is truly new for me. But looking at the abrasion marks look like some pivot point coupling. The stainless pin should rotate inside of the plastic part (low friction couple) and the bronze pin (is bronze?) should rotate too. $\endgroup$
    – Leafk
    Dec 22, 2019 at 13:46
  • $\begingroup$ @morbo the parts are a pair so I think if I could find them in a catalog (hopefully with application information) that would be good. $\endgroup$ Dec 22, 2019 at 15:15
  • $\begingroup$ @morbo The rig was to create small accelerations (simulating residual accelerations on a stabilization platform during flight of an aircraft) on a cryogenic gravity gradiometer instrument. It had (at least) 5 DOF driven by individual magnetically shielded electromagnetic shaker units. There were 3 pairs of extension springs, 3 of the above devices arranged radially about the Z axis. $\endgroup$ Dec 22, 2019 at 15:19
  • $\begingroup$ assuming that was a tight fit, could that not be a dampening unit of some kind then? $\endgroup$ Dec 22, 2019 at 15:21

1 Answer 1


Okay, I found an engineer who was familiar with the way they were used and it's not particularly exciting.

The three parts were screwed in to immobilize the motion platform while the cryostat etc. was being loaded and unloaded via a crane, then screwed out to free the motion. There was no deliberate damping other than that created by driving the electromagnetic shakers through a low-impedance source.

Frankly, I like the other ideas better.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.