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School me on micrometers

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  • School me on micrometers

    Found a deal in Michigan that Flylo didn't get to first. Small Kennedy with "misc tools" for $40. Kennedy will clean up nicely and the interapid was a nice bonus. Also included were four micrometers. One is a no-name "made in japan" that (once the adjustment was freed up) has a very good feel. Two "Craftsman" D.J. marked (0-1 and 1-2 in tenths) and a B&S #2.

    The Craftsman are (I think) Mitutoyos. They look like these:
    (sorry couldn't find a non-ebay image)
    How does the sleeve adjust for zero on these? I don't want to reef down on something until I know for sure. Also - the ratchet seems too tight (a lot tighter than what I consider a good feel). Is the ratchet force adjustable?

    The B&S doesn't have as good of a feel. What I mean by that is that on the no name "made in japan" the range of repeatable readings is very small - it feels very crisp when the anvils close on something. On the B&S there is a 2-3 tenths variation in reading with the same feel. Is this something that can be adjusted with the nut on the split barrel that appears when completely unscrewed? How is this typically adjusted? How tight is too tight and how loose is too loose?

    Also on the B&S I think it is "convertible" between feel and friction but for the life of me I can't see how that is done.
    Looks a lot like this one:
    (I'll take some pics tonight and get rid of these ebay links).

    Also, what is the deal with the "slant" lines instead of straight?

  • #2
    The ebay Cr'mn seems to have a wrench hole in the thimble. You likely loosen the end cap, then reset the thimble with the anvils set to the reference piece.

    The friction/feel is adjusted by turning the end cap. Cranked down it is all feel, loosened it is friction. Can be a tricky adjustment, and the feel system is easily gummed-up, so it may not be working. I had to hit mine with solvent until it loosened up.

    Keep eye on ball.
    Hashim Khan


    • #3
      Also, what is the deal with the "slant" lines instead of straight?
      IIRC, some makers use the "slant" line for the next finer mics are a good mix of makers and don't have any within reach at the moment, I think some use a much longer straight line and some use a slant line, so to .0001 as opposed to .001 (resolution the correct term, I think..)


      • #4
        Originally posted by dockterj View Post
        The Craftsman are (I think) Mitutoyos.
        Don't think so. I have kept an eye open and have those C'man mics in 0-1,1-2,2-3 and 3-4" sizes. I think they're Starrett.

        If you decide to pursue them be sure to only buy the ones that read in tenths.



        • #5
          The slant lines on a B&S are to make reading the barrel easier. With straight lines sometimes it's hard to tell if a line is covered up or which one to read. With the slant lines, you look for the intersection of the slant line and the zero datum line.

          I think the Craftsman ones are made by Starrett.


          • #6
            1. Every micrometer I have ever seen is zeroed by loosening the end cap, possible loosening a nut under that cap, adjusting it, and re-tightening. The hard part, especially on tenths reading micrometers, is locking the adjustment down as it will easily change by several tenths. It is cut and try for several cycles. How that end cap is loosened is different. Sometimes there are holes for a spanner wrench, sometimes you just have to grip it carefully, sometimes something else.

            2. Is the ratchet force adjustable? I have never seen one that is, but anything is possible. If it is a "click" type I would try a drop of oil first and exercise it for a while to distribute that oil. If you try to disassemble it, do take precautions against flying pieces, like small springs. A friction style is more likely to be adjustable.

            Note: the idea of the ratchet or friction spindle is to provide a CONSTANT amount of pressure when tightening. The frame of the micrometer, of ANY micrometer, WILL bend a few tenths. Perhaps as much as a thousandth or two. So CONSTANT pressure to produce a CONSTANT amount of bend is necessary for accurate measurements.

            3. You say, "On the B&S there is a 2-3 tenths variation in reading with the same feel." If you are really taking these readings on a constant dimension, this is a problem. THAT is a BIG if.

            First check to be sure any spindle lock is working properly and not set on. Be sure the contact faces are clean and have no burrs. I would take the spindle out of the barrel and clean the threads. Use a long cotton swab with some solvent for the internal threads: actually use several. Then re lubricate it with a quality, light oil. That is a precautionary measure to be sure the problem is not some drag.

            Next, if this mike does not have a ratchet, you may have to practice your "feel". In effect, YOU are the ratchet. With a ratchet or friction stud the readings should be consistent.

            4. You say, "Also on the B&S I think it is "convertible" between feel and friction ...". I am not sure what you are saying. Every mike with a ratchet or friction stud can be considered "convertible". If you tighten it with the ratchet, it is done that way. If you grab the spindle below the ratchet and avoid using the ratchet, then you are doing it by feel. I guess you could grab both, but that would be confusing. On the other hand, if the mike does not have a ratchet or friction stud, then you are simply stuck with doing it by feel: there is no other possibility.

            5. I have no idea as to what you are talking about when you say "slant lines". Your link goes to a closed E-bay auction and the photo there is too small to see any detail. You need to post a photo of this. All I can think of is, it is possible that a Vernier scale for tenths may have some slanted lines to allow the numerals to be separated more so they can be larger and easier to read. I believe I have seen some mikes with that. If so, then the slanted lines are not used for the readings, just to connect the parallel lines which are used for the readings with the larger numbers.
            Paul A.

            Make it fit.
            You can't win and there is a penalty for trying!


            • #7
              Originally posted by Paul Alciatore View Post
              1. Every micrometer I have ever seen is zeroed by loosening the end cap, possible loosening a nut under that cap, adjusting it, and re-tightening.
              k, I'm missing someting.... everyone I've seen, Starrett, M&W, B&W, Etalon, Mitutoyo, the Germans and so on is zero'd by using the wrench to move the friction fit barrel

              The Craftsman are (I think) Mitutoyos. They look like these:
              don't think so, looks like a Starrett, Slocomb or Lufkin to me. From that era Crafstman would have outsourced to a American firm likely, and I've not seen a mit mic that looks anything like that


              • #8
                I also have some Craftsman mics and they appear more Starrett-like to me.


                • #9
                  As promised - pictures. First the B&S

                  The manual is 1971 (IIRC). Notice the slant lines under the zero line on the barrel (I believe I have the correct terms).

                  A copy of the relevant catalog page. "Convertible from friction action to feel by reversing sleeve."

                  A better view of the "slant line." A quick google search seems to indicate this wasn't a welcome feature; apparently it is an evolutionary dead in in micrometer history.

                  This one adjusts by turning the barrel. Here is the hole for the spanner wrench.


                  • #10
                    The nut on the end of the split barrel.

                    The cap nut comes off. It is a left hand thread. I believe this is the start to switching from a feel to a friction thimble.

                    1. I can turn the barrel to set zero but zero doesn't line up laterally. Is it typical to move the barrel back and forth to set zero to coincide with the (slanted) zero line?
                    2. Any idea how the conversion from feel to friction is done?
                    3. How is the barrel nut adjusted? Does this affect the feel?


                    • #11
                      I was thinking Lufkin myself.....based on "look" but could be any of those mentioned. The adjustment means might be a clue.

                      The section between the nut you removed, and the main knurled area is turned to change over, IIRC. If you turn it to clamp down on the main section, it is "feel", if you back it off against the nut, it is "friction". The friction mechanism needs to be clean and lightly oiled. It's usually a couple turns of wire that tighten onto the barrel under the loose knurled area when closing the anvil down on the part. Loosens when reversed.

                      The nut you see if you unscrew the thimble/anvil assembly sets the slop of the screw. If set too tight, it will affect feel. if set loose you can feel some movement. It should be set to just stop axial slop, which will likely also make it stop positively on the item being measured.

                      Make sure some dim bulb didn't grease it, as that can make it close with a "squeezy" sort of feel. Clean it and oil lightly with something like Starrett instrument oil. Adjust to barely remove the slop. If it is too hard to turn it will always feel "squeezy".
                      Last edited by J Tiers; 11-24-2015, 12:03 AM.

                      Keep eye on ball.
                      Hashim Khan


                      • #12
                        As to the original manufacturer, I think they are Scherr-Tumico. S-T made a lot of stuff for other companies as well as under their own name. They were good tools. The barrels on the Craftsman mikes look like S-T.



                        • #13
                          Learn something new every day (previous comment was about entirely different series of lines), I can sort of see why it would not be favorite.


                          • #14
                            And the Craftsman. I thought Mitutoyo based on an internet chart that said Mitutoyo made the D.J. marked instruments but that doesn't make sense with them also marked made in USA.

                            The adjuster hole for the spanner wrench. No, the monkey marks aren't from me. My best guess is that the small part with the divisions rotates separate from the rest of the thimble but I am not 100% sure of that.

                            Plastic barrel nut on this one. Both of these were very loose when I got them so I could only make them better by playing with them.

                            The ratchet comes off easily enough. I'm thinking the moving anvil is threaded on the OD and screws into the thimble and is threaded on the ID and the ratchet screws into it.


                            • #15
                              re: craftsman mics

                              I was thinking Starrett as well based on the lock mechanism but it isn't exactly the same.

                              This is interesting:
                              Item 397 and the history for Sears says in the 70s Sherr-Tumico made these for Sears. Sarge looks like you win the cigar today!

                              J thanks for the advise. I'll clean again before doing anything else.