Announcement

Collapse
No announcement yet.

Corrosion on mic anvil

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Corrosion on mic anvil

    Would this corrosion be a problem? It's on a Starrett 436 - i.e., not a Super Mic.

    Click image for larger version

Name:	s-l1600.jpg
Views:	233
Size:	69.6 KB
ID:	1905558


    If so, is it readily fixable?

  • #2
    Probably not a problem. So long as nothing on the anvil is sticking UP, most things you measure are either flat or have a flat line like a cylinder.

    Instrument repair shops can fix that by re-lapping the anvils. I wouldn't recommend it as a home shop fix since one is much more likely to make them angled or spherical without the right equipment.
    .
    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

    Comment


    • #3
      I would not touch it, it will be fine for most jobs. Set the zero and try measuring some slip gauges, this will tell you the condition of the threads.

      Comment


      • #4
        Originally posted by TGTool View Post
        Probably not a problem. So long as nothing on the anvil is sticking UP, most things you measure are either flat or have a flat line like a cylinder.

        Instrument repair shops can fix that by re-lapping the anvils. I wouldn't recommend it as a home shop fix since one is much more likely to make them angled or spherical without the right equipment.
        Any reason not to wipe it with a little phosphoric acid on a Q-tip? Stop the rust process, probably remove most of the loose particles?

        Comment


        • #5
          Thanks for the replies. If something was sticking up & it wasn't a burr, but "rust" (steel expands when it rusts), would Evaporust be safe? Wouldn't it just attack the rust & not the steel, as acid would?

          Comment


          • #6
            Stick it anvil deep in Evapo-Rust.
            “I know lots of people who are educated far beyond their intelligence”

            Lewis Grizzard

            Comment


            • #7
              https://www.starrett.com/metrology/p...detail/09014-0

              Comment


              • #8
                Great answer, no snark, no pomposity, just good help. Also solved a problem for me. Thanks!

                Comment


                • #9
                  Not that great of an answer. The anvil of a micrometer isn't a part you can just pop out and slap a new one in. It will almost certainly need to be lapped into correct alignment after it's changed. Which isn't an "at-home" job for most folks.

                  Comment


                  • #10
                    Originally posted by reggie_obe View Post

                    Any reason not to wipe it with a little phosphoric acid on a Q-tip? Stop the rust process, probably remove most of the loose particles?
                    No need to fool with it at all. At this point there's almost certainly a little oil in the depressions so it's not actively developing more rust. If you haven't oiled it you can do it now.
                    .
                    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

                    Comment


                    • #11
                      Easy , safe, and often fixes issues...... get a piece of index card or stiff rough paper. Close the mic on the paper as if you were measuring it, just a little more snug. Pull the paper out. That will take particles out, and not affect the surface. Paper has a small silica content, so it is a very mild abrasive, and the fibres latch onto particles.

                      Your clean fingertip also works.

                      Sometimes, a little solvent or oil on the paper will clean off greasy gunk, which may be half of it.

                      If there really is a problem of particles (rust, dust, tiny swarf, etc), so it is not just a stain, you may find that the mic does not zero reliably, it may vary near zero, changing with each time you try. So clean it off. Paper, your clean finger, etc.
                      Last edited by J Tiers; 10-18-2020, 09:50 PM.
                      1601 2137 5683 1002 1437

                      Keep eye on ball.
                      Hashim Khan

                      If you look closely at a digital signal, you find out it is really analog......

                      Comment


                      • #12
                        I was going to suggest something similar. It probably would not hurt to use one of the rust dissolving solutions soaked into the card stock if you use a neutralizing solution after it and then some water, also soaked into the card stock. Use a fresh strip of card stock each time, of course.

                        And the amount of abrasive in card stock will be very small so you can use a dry piece of it several times without making any major changes. Dare I say, many times. But only do it as many times as produces improvements. Use some caution. You can use the ball bearing ball check I speak of below to judge any progress here.

                        If this is a thousandth reading mike, it will probably be OK. Just zero the scale after cleaning it.

                        If it is a tenths micrometer, then you could test it after cleaning. Use a new ball bearing ball, about the diameter of the anvils. Measure that ball with the points of contact at the center and at a number of other points around the anvils and see how much variation you get. This will tell you how many tenths it may be accurate to. I have an older micrometer with a Vernier scale for tenths. It's anvils are not carbide, just steel. When I used a ball to test it, I saw that it has about a 0.0001" to 0.0002" slope on one of the anvils. So, I only trust it to +/- 0.0002".

                        Ball bearing balls are very consistent in diameter in all orientations.



                        Originally posted by J Tiers View Post
                        Easy , safe, and often fixes issues...... get a piece of index card or stiff rough paper. Close the mic on the paper as if you were measuring it, just a little more snug. Pull the paper out. That will take particles out, and not affect the surface. Paper has a small silica content, so it is a very mild abrasive, and the fibres latch onto particles.

                        Your clean fingertip also works.

                        Sometimes, a little solvent or oil on the paper will clean off greasy gunk, which may be half of it.

                        If there really is a problem of particles (rust, dust, tiny swarf, etc), so it is not just a stain, you may find that the mic does not zero reliably, it may vary near zero, changing with each time you try. So clean it off. Paper, your clean finger, etc.
                        Paul A.
                        SE Texas

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

                        Comment


                        • #13
                          they made this comparison page: https://littlemachineshop.com/Info/minimill_compare.php which is why I bought this mill.

                          send it back: there's a thought. re-crate it, wait a week for the truck to show up, wait two weeks for them to deliver it, wait a week while they do what they do, wait... thank you, no.

                          I will try the big honking allen wrench in the chuck and a cheater bar

                          Comment


                          • #14
                            This is why I like carbide tipped mics.

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

                            Comment


                            • #15
                              With some rust pitting, the accuracy when measuring a bearing ball would depend whether you were unlucky enough to line up with a pit. The mic will be better used to measure flat surfaces.

                              Comment

                              Working...
                              X