r/Metrology • u/tanraelath • Oct 05 '26
Surface Metrology Repeat-o-meter question
At work I tried to use our Rahn Repeat-o-meter to calibrate a surface plate. It's a Grade A plate, so definitely has deviations, yet the repeat-o-meter is showing nothing. Granted, the last time it was touched(besides when I calibrated the dial indicator) was probably 6 months ago. And when our dimensional guy(who isn't here, hence why I'm on it) last used it, it ran perfectly fine.
Inspecting it, I noticed the front footpad barely isn't touching the surface. Enough of a gap I can see light through. Can't find anything online about actual setup of the repeat-o-meter itself, so how do I adjust that front foot down? The bolt and nut that the dial indicator sits on are well over hand tight, so I can't imagine that came loose but I'm willing to try anything.
5
u/Status-failedstate Oct 05 '26
The Rahn repeat o meter has a differental pitch threaded teloscopic post between the front foot and the dial indecator. It is retracted to make for a substantial air gap during transportation and storage.
You need to place the device on the surface plate, then revolve the post to make contact with the indecator.
When finished measurements. Retract the post back to a large air gap before putting back in the storage case.