Announcement

Collapse
No announcement yet.

thread micrometer.

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

  • thread micrometer.

    They are damn expensive.Even three wire guage sets are expensive. An here in Africa not so easy to get.Is there a way around it . ?What would happen if you made some sort of split piece anvil .One for each size thread Sort of like a split bush that has an internal thread but it is used as a comparator to a known thread . Would it work.

  • #2
    There is also what is called "thread triangles" so that you do not need a different tool for each size. It liiks like they would not be too hard to make. Here is one example: http://www.fowlerprecision.com/Produ...526033030.html

    Comment


    • #3
      Check out Fisher Pee Dee wires. They should be under $30US. Finding a vendor to ship to you may be a problem. The Pee Dee wires will not be as accurate as 3 wire sets but the are fine.
      Most industrial supply houses handle the Pee Dee wires.

      Comment


      • #4
        Originally posted by plunger View Post
        They are damn expensive.Even three wire guage sets are expensive. An here in Africa not so easy to get.Is there a way around it . ?What would happen if you made some sort of split piece anvil .One for each size thread Sort of like a split bush that has an internal thread but it is used as a comparator to a known thread . Would it work.
        I imagine it would work, but you would have to calibrate it somehow. Could it be made to work with existing tables of pitch diameters?

        Comment


        • #5
          importium thread wires are about $20 on ebay, I got a set

          Comment


          • #6
            Arc euro trade in UK has inexpensive set and they ship abroad. Dunno about SA.
            Was unable to find from china/aliexpress.. Postage should be reasonable for small item like that.

            https://www.arceurotrade.co.uk/Catal...t-with-Holders
            Location: Helsinki, Finland, Europe

            Comment


            • #7
              Originally posted by Ringo View Post
              importium thread wires are about $20 on ebay, I got a set
              I think the problem is the South African authorities double the price on all imports. 20 USD works out to ~350 SAR before you even pay the taxes and import fees. And then it could take months to get there.

              If it was me I would carefully measure some drill bit shanks and use those instead of getting ripped off on thread wires.

              Comment


              • #8
                Drills or any round object within a thou on dia, that fits and allows measurement. Put a flat bar or toolbit across 2 if needed.

                Comment


                • #9
                  Originally posted by 754 View Post
                  Drills or any round object within a thou on dia, that fits and allows measurement. Put a flat bar or toolbit across 2 if needed.
                  I saw a calculator on the internet that would give you the measurement over the wires for any given diameter of thread wire.
                  so yeah, you could use a variety of drills shanks, and get the measurement over the wires, and no, it doesn't have to be within a thou or 2.
                  it had a wide range

                  Comment


                  • #10
                    Next question are you duplicating a thread in hand by this method, or working out of a book or chart, or online measurement ? If the last is your case , then size of rods really matters.

                    Comment


                    • #11
                      Just out of curiosity. Say I wanted to just help a guy in SA out and mail him a set of thread wires that pretty much fit in a regular envelope, how difficult or expensive would that likely be? A set would pretty much fit in a regular letter envelope.You could tape them to a sheet of folded up paper, for that matter.
                      Any idea? Would it likely disappear in the mail?

                      Comment


                      • #12
                        The wires used for the three wire method only need to fit in a certain area of the flanks of the thread. There is a formula that lets you calculate the correct sized wire given any TPI (or pitch). If you look at https://www.threadcheck.com/the-thre...technicalinfo/ you will see that the formula for a 60 degree thread is simply 0.57735 times the pitch. Pitch is, of course the number 1/TPI. So to get a usable set of wires for a 8 TPI thread, any wire that is close to .07216 can do the job. A #49 drill is .0730 inch, so it will touch close to the right place on the flank and you'd plug the difference between .07216 and .0730 into the calculations for the proper pitch diameter.

                        The reason all this works is that the geometry of the thread is determined by a formula. The pitch diameter is also determined by a related formula.
                        Dan

                        At the end of the project, there is a profound difference between spare parts and extra parts.

                        Location: SF East Bay.

                        Comment


                        • #13
                          If you can get the wire from a MIG welder or some gas welding rod or nice straight pieces of solid copper wire. Could you come close enough for your needs. I have a set of wires so have never played around with anything else.
                          Somewhere I saw a formula for using different diameters for this task.

                          Comment


                          • #14
                            You will notice a curious difference here, sets of 48 thread measuring wires are less then $50.00 US, once you decide that you need 4 decimal place accuracy the cost rises to $75.00-$200.00 US for a single 3 wire set, welcome to machining.
                            https://www.mscdirect.com/browse/tn/...navid=12107674

                            Comment


                            • #15
                              Originally posted by plunger View Post
                              They are damn expensive.Even three wire guage sets are expensive. An here in Africa not so easy to get.Is there a way around it . ?What would happen if you made some sort of split piece anvil .One for each size thread Sort of like a split bush that has an internal thread but it is used as a comparator to a known thread . Would it work.
                              Yes, they are expensive, and an absolute must have for production runs and for use in a manufacturing inspection department. In our home shop type operations we learn to make do with what's available and within budget. No harm in that. What you propose with a threaded split bushing design would work well where you are eliminating calibration issues by having a thread of known quantity to use as a comparison. You will probably see more consistent results than using a three wire, as there is more contact area. Accuracy in the three wire method is heavily dependant on operator "feel". Again, you'd be using this not for measurement, but for comparison so it all depends on the accuracy of the sample thread used. Might be a good idea to not make the bushings too long, ,as there could be slight lead errors between the two threads being compared, assuming at this point you're only going after the pitch diameter.

                              Comment

                              Working...
                              X