So I can use the 3 plate method to make some really flat surfaces. I can then use one of my surfaces with a surface gauge to make a block with parallel faces. What's not clear to me is how gauge blocks are manufactured:

  • With really parallel faces
  • To a submicron thickness tolerance
  • With a mirror surface finish
  • At scale
  • At an affordable price

I know that lapping is involved but it'd like a bit more detail.

  • $\begingroup$ Perhaps check out Youtube channels - Abom79, Cee Australia, Keith Fenner, Snoball Engineering will give you an idea of many of the processes used. $\endgroup$
    – Solar Mike
    Nov 12, 2023 at 17:01
  • $\begingroup$ Plenty of people on youtube making parallels, lapping stuff, etc. but not aware of any youtube vids showing gauge block mfg. Certainly not the kind of thing you're going to find on abom/cee/keith's channels. $\endgroup$
    – HJCee
    Nov 12, 2023 at 17:08
  • $\begingroup$ You omitted an important point (and quite a difficult one, as a matter of fact): adjacent sides must be perpendicular. $\endgroup$ Nov 13, 2023 at 3:12
  • $\begingroup$ @JerryCoffin Are you sure about that? I don't see why gauge blocks need perpendicular sides. As far as I know, that's not the way they are used. $\endgroup$
    – DKNguyen
    Nov 13, 2023 at 3:43
  • $\begingroup$ @DKNguyen: It isn't strictly required, but quite a few people take for granted that they will be quite perpendicular, and (at least most) vendors seem to oblige by ensuring they are. $\endgroup$ Nov 13, 2023 at 4:06

1 Answer 1


You can find quite a bit by looking through old patents. Gauge blocks have been around long enough that many of the relevant patents are around a century old or so.

Here are a couple of examples:



These contain references to other patents as well.


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