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  • Jo Blocks Maintenance Question

    My set of shop blocks has suffered from neglect while my shop was in storage. I would like to restore them as best as I can. And yes, at some point I will probably just purchase a new set, but I have other, higher priorities.

    What I see on many of the blocks, even on some that have never even been removed from the original, factory protective wrap, is a discoloration on the faces. I have tried several, non abrasive ways of cleaning them with mixed results. I can remove that discoloration from them, but it takes a lot of work and that means a lot of time for the entire set. Frankly, more time than the set is worth.

    I have seen ads for stones that are intended to be used on Jo blocks. These stones seem to cost as much as my set of shop grade blocks originally cost. Perhaps I should just break down and get one. But I also have a pair of ground, flat stones.

    The ground, flat stones, when properly used will not produce any measurable differences, even down to the tenths range. But the Jo blocks are supplied with actual sizes down to the millionth of an inch. So I am wondering if there is any difference between the ground, flat stones that I have and the Jo block stones sold for that use. Would, perhaps, the ground, flat stones produce a surface finish that would prevent wringing?
    Paul A.
    SE Texas

    And if you look REAL close at an analog signal,
    You will find that it has discrete steps.

  • #2
    If discolored then toss them even if they are accurate, your profound OCD will never let you rest otherwise.

    In future buy ceramic blocks only.

    On second thought they may also discolor in use. The only solution that comes to mind is to buy new blocks and store them in a controlled environment and NEVER use them under any circumstances, buy a second set to actually use with considerable disdain resulting from the contamination from use. This method assures that you have uncontaminated standards at hand.

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    • #3
      OK, they're discolored. Do they still wring? If so, what's the problem?

      -js
      There are no stupid questions. But there are lots of stupid answers. This is the internet.

      Location: SF Bay Area

      Comment


      • #4
        The chromium carbide ones are nice. I don't believe you have to worry about staining or corrosion as much as the steel ones.

        JL....

        Comment


        • #5
          OK, (yeah, I know) "for the home shop" discolored gauge blocks are probably just as good as shiny ones. Even if they do not wring.

          What do you use them for? Generally calibration, sometimes for measurement. Since most have tools that are really not intended for work to tolerances significantly below a thou, even blocks that have been "surveyed out" are likely to be good for them.

          I have some loose "extra" non-wringing blocks that measure to the same size as the ones that do wring, "as far as my measuring tools can tell". Since I only go to tenths increments with the mics, that is my limit on accuracy.

          Where you end up with an issue is with stacks of blocks to make up larger and odd sizes. There, you want the full accuracy of the blocks due to the stack-up of errors. But even there, the discoloration has not produced errors of size that I can detect as compared to the good set.

          YMMV.... your "discoloration" I might consider to be "horrible corrosion", I dunno. You know, the "surface rust" mentioned in an ebay ad.........
          CNC machines only go through the motions

          Comment


          • #6
            I have, and occasionally use a set of Jo blocks made by my late friend John Crook. He made them using his employers set for comparison
            They are rather stained and tired looking from years of use and later poor storage. However, most still will wring together.
            John told me they are not perfect, but they are adequate and still accurate enough for my needs, I build steam engines not space rockets,
            Regards David Powell.

            Comment


            • #7
              Gee, thanks!

              Did I really deserve that?



              Originally posted by Bented View Post
              If discolored then toss them even if they are accurate, your profound OCD will never let you rest otherwise.

              In future buy ceramic blocks only.

              On second thought they may also discolor in use. The only solution that comes to mind is to buy new blocks and store them in a controlled environment and NEVER use them under any circumstances, buy a second set to actually use with considerable disdain resulting from the contamination from use. This method assures that you have uncontaminated standards at hand.
              Paul A.
              SE Texas

              And if you look REAL close at an analog signal,
              You will find that it has discrete steps.

              Comment


              • #8
                And we wonder why the number of posts are going down.....

                Comment


                • #9
                  If the staining is from dried oil you should be able to remove it with thinner. Thinner cuts everything. If it's from rust / oxidation doubtful you'll be able to remove it without changing the dimension of the block.
                  Starrett has a soft stone used for surface cleanup of gage blocks but I believe it's for removing surface imperfections like small dings etc. The tech told me that it won't change the dimension of the block. The best way to store them is to wipe them with a film of petroleum jelly and put a sheet of anti corrosive paper in the box.

                  As far as wringing...... you don't need a gage block finish for parts to wring together.

                  I have a good set and a knock around set for machine set ups etc.

                  JL.............

                  Comment


                  • #10


                    Originally posted by Paul Alciatore View Post
                    Gee, thanks!

                    Did I really deserve that?
                    No, you did not.

                    It's just another "pro" yanking the chain of the "home shop Harry" folks who are deemed "clueless amateurs" who have trouble finding the handle end of a screwdriver..

                    Some "pros" do that, most do not. Agree that it does not help the site gain new members.
                    Last edited by J Tiers; 04-14-2021, 09:19 AM.
                    CNC machines only go through the motions

                    Comment


                    • #11
                      Hello Paul,

                      I use my ground flat-stones to repair my gage blocks. First I use the course side of the stones to remove any burrs, then the fine side to finish. As you know when properly used, the flat-stones will not remove material on the surface plane. I have repaired blocks that would not wring to wringable condition using the flat-stones.

                      In my experience some of the discoloration that comes from oxidization will not prevent blocks from wringing once they are stoned. And It may be necessary to regrind the stones to remove the stains. I would not recommend that for shop grade gage-blocks. Stone them with the flat-stones. Verify they will wring properly. Then oil them. Hope this helps.

                      Best Regards,
                      Bob
                      Last edited by rjs44032; 04-14-2021, 03:22 PM.

                      Comment


                      • #12
                        Thanks Bob, that is a most useful answer.



                        Originally posted by rjs44032 View Post
                        Hello Paul,

                        I use my ground flat-stones to repair my gage blocks. First I use the course side of the stones to remove any burrs, then the fine side to finish. As you know when properly used, the flat-stones will not remove material on the surface plane. I have repaired blocks that would not wring to wringable condition using the flat-stones.

                        In my experience some of the discoloration that comes from oxidization will not prevent blocks from wringing once they are stoned. And It may be necessary to regrind the stones to remove the stains. I would not recommend that for shop grade gage-blocks. Stone them with the flat-stones. Verify they will wring properly. Then oil them. Hope this helps.

                        Best Regards,
                        Bob
                        Paul A.
                        SE Texas

                        And if you look REAL close at an analog signal,
                        You will find that it has discrete steps.

                        Comment


                        • #13
                          Originally posted by J Tiers View Post



                          No, you did not.

                          It's just another "pro" yanking the chain of the "home shop Harry" folks who are deemed "clueless amateurs" who have trouble finding the handle end of a screwdriver..

                          Some "pros" do that, most do not. Agree that it does not help the site gain new members.
                          In this you would be incorrect, there are people in every hobby/business/pass time that exhibit similar behavior, as an example the person that runs the office where I work will only leave the building through the SAME door that they entered it at first, no exceptions.

                          People have firm beliefs that are often not rational yet makes them happy, let them have at it.
                          Last edited by Bented; 04-14-2021, 07:05 PM.

                          Comment


                          • #14
                            Originally posted by Bented View Post

                            In this you would be incorrect, there are people in every hobby/business/pass time that exhibit similar behavior, as an example the person that runs the office where I work will only leave the building through the SAME door that they entered it at first, no exceptions.

                            People have firm beliefs that are often not rational yet makes them happy, let them have at it.
                            Ah, so this is "compelled behavior" on your part? Just like leaving the building through the same door you come in through?

                            Well, then, we'll assume you cannot hep it, and just accept your peculiarities. Everyone has some.....It's OK 😉
                            CNC machines only go through the motions

                            Comment


                            • #15
                              remove burrs? from hardened precision blocks? what might they have been used for? dont touch the blocks. if they wring they are o.k. if not, find an appropiate use for them. these are calibration devices.

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