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  • Repairing gage blocks

    I got myself a few used gage blocks off ebay to play around with micrometer testing and measurements. Most are in good condition, but some have little dents near the corners that prevent a good wring. Since I am just playing around, I would like to be able to repair them for cheap.

    The official Starrett gage block stone is $100. I don't feel like paying that much.

    Over on PM, there have been various admonitions about taking any kind of abrasives to these blocks. To be honest, I am not worried about taking off a few millionths, as long as I can still get a good wring.

    I also don't have an optical flat for finding tiny defects, although I may be able to ghetto rig something up for cheap by getting an un-aluminized mirror, which has one really flat side, and one frosty side. There is a trick where you can clear up the frosty side by putting a piece of scotch tape over it.

    Failing that, is there some scraping-related way of finding the high spots, like bluing up the face and rubbing it on something flat?

    Some of the things I have at my disposal are:
    Diamond file
    very fine sandpaper
    an aluminized mirror which probably is very flat.

  • #2
    Probably easier and cheaper to buy new ones (though they do get expensive if bought one by one, a set is always a good option). If you can't stone two pieces of steel to wring together, then you won't be able to fix those blocks either.
    Amount of experience is in direct proportion to the value of broken equipment.

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    • #3
      These ones were dropped and hit on the corner. Just use the diamond file on the raised area only and don't mess with the main surface. Then you can wring them together and they will maintain their accuracy. The corners and edges don't matter.

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      • #4
        Any worn or damaged blocks are now simple spacers.

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        • #5
          beanbag;840271 " I got myself a few used gage blocks off ebay to play around with micrometer testing and measurements. Most are in good condition, but some have little dents near the corners that prevent a good wring. Since I am just playing around, I would like to be able to repair them for cheap.

          The official Starrett gage block stone is $100. I don't feel like paying that much."

          Good thinking, used blocks are not worth that much.

          "Over on PM, there have been various admonitions about taking any kind of abrasives to these blocks. To be honest, I am not worried about taking off a few millionths, as long as I can still get a good wring."

          Not likely

          "I also don't have an optical flat for finding tiny defects, although I may be able to ghetto rig something up for cheap by getting an un-aluminized mirror, which has one really flat side, and one frosty side. There is a trick where you can clear up the frosty side by putting a piece of scotch tape over it."
          If you are talking mirror as in looking glass, both sides are equally wavy. If that would work , there would be no market for optical flats.

          "Failing that, is there some scraping-related way of finding the high spots, like bluing up the face and rubbing it on something flat?"
          No.

          "Some of the things I have at my disposal are:
          Diamond file
          very fine sandpaper
          an aluminized mirror which probably is very flat."

          It could keep you out of trouble for a while.

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          • #6
            The important parts of gage blocks are the two faces. Every thing else is just there to support them.

            If you remove the dinged parts of the faces, without damaging the good parts, the accuracy has not been damaged enough to bother *you*. The NIST would care, but the NIST would "laugh at" the gage blocks anyway. They have better things, and you don't.

            Will the work throw them off a bit? Yep.

            Can you tell the difference in size before and after? Nope..... and neither can most of the folks who are telling you it's silly.

            What have you got to lose?
            1601

            Keep eye on ball.
            Hashim Khan

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            • #7
              you could lap each of the 81 pieces down to the next smaller size, but its a lot of work
              .

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              • #8
                Originally posted by beanbag View Post
                The official Starrett gage block stone is $100.
                Anyone know what grit the Starrett gauge block stone is?

                I ended up with a miniature Collins MicroFlat "surface plate" (the surface is about the size of a business card) that I assumed was intended as a paperweight, but I wonder if its actually a gauge block stone?
                "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                • #9
                  The un-aluminized mirrors are 1/10th wavelength on the smooth side and frosty on the rough side. The store checked that indeed the scotch tape trick works to clear up the frosty side. For $6, that's not a bad deal. (surplusshed.com) However, it's not an optical parallel, like in those mic check kits.

                  BTW, the larger blocks are the super bling Webber croblox. They are reputed to have good dimensional stability, so even though they aren't recently certified, they are probably still good.

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                  • #10
                    Originally posted by lazlo View Post
                    Anyone know what grit the Starrett gauge block stone is?

                    I ended up with a miniature Collins MicroFlat "surface plate" (the surface is about the size of a business card) that I assumed was intended as a paperweight, but I wonder if its actually a gauge block stone?

                    All I know is that there is more than one Starrett stone. There are two that are Sintered Aluminum Oxide and work on carbide blocks (part number SAO**) and another one which I forgot, but the part number is GS** and it is for steel only.

                    I imagine the only difference between their stones and normal ones is that they are super flat and very fine, although I don't know the grit. Is it possible for the grit to be so fine that if you use oil, the block floats on this oil layer and the stone really does only take off the high spots?

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                    • #11
                      Originally posted by Mcgyver View Post
                      you could lap each of the 81 pieces down to the next smaller size, but its a lot of work
                      Probably the funniest, while still correct, thing posted on HSM in a long while.

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                      • #12
                        The real laugh is-----

                        Originally posted by adatesman View Post
                        Probably the funniest, while still correct, thing posted on HSM in a long while.
                        Mcgyver is a very capable and determined fellow. He probably could actually do that, to a standard for the blocks to be useful in a home shop environment. But I would not expect him to waste his time doing so, machine tools are much more fun.( His eyes light up when he looks at those in need of TLC, bet he is not much of a card player. Regards David Powell.

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                        • #13
                          Brownell's www.brownells.com used to sell, and maybe still does, a fine ruby stone that is so fine it has no noticeable "grit" at all -- it's smooth. Expensive though, and possibly not very useful. It would take "forever" to stone off even a small burr with it.

                          I'd opt for maybe a fine hard Arkansas stone or even a fine India stone as fine enough for what you need to do. As others have said, knock off just the burrs and try not to touch the rest of the surface.
                          ----------
                          Try to make a living, not a killing. -- Utah Phillips
                          Don't believe everything you know. -- Bumper sticker
                          Everybody is ignorant, only on different subjects. -- Will Rogers
                          There are lots of people who mistake their imagination for their memory. - Josh Billings
                          Law of Logical Argument - Anything is possible if you don't know what you are talking about.
                          Don't own anything you have to feed or paint. - Hood River Blackie

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                          • #14
                            What about taking the edge back enough to remove the damage (say 45 degree), this way your not touching either face.

                            Dave

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                            • #15
                              Just touch the corners up with a diamond file to remove any raised nicks.

                              If any are damaged on the face, you could try painting them with sharpie felt pen and then using a high grit diamond file on them till sharpie all over the face is knocked off (Not all of it, just spots all over the face)
                              Likey take off a few ten thou, but then, you likey only care about thou accuracy anyway or you wouldn't be trying to repair these.
                              Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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