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rpm counter

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  • rpm counter

    well as the title says, I need to keep track of total number of revolutions a machine makes in a , any ideas?

  • #2
    roughly what speed and what time period , what precision? mo' info please.

    Could be done with a automobile odometer. They are direct drive through gears, problem would be reading precisely- though over a day or so the accuracy (at higher speeds ) would be extremely good. Too many solutions available- need to give info so some drop out.


    • #3
      They are in the mcmaster-carr catalog for various machine set-ups.
      Non, je ne regrette rien.


      • #4
        I'm not sure where you would find one but I have a rev counter that goes up to 9999. It's a tiny little thing, purely mechanical but very handy when winding coils.

        Try to find an old photocopier with an electromechanical meter. They were as common as dirt and you might find one in a surplus store somewhere. Some even have reset mechanisms. They run on a pulse of 24 volt DC, one count per pulse. It should be easy to rig a microswitch to provide a pulse from the spindle.

        Of course you could make an electronic one as well using a counter chip. Follow the link for complete info on how to build one.
        Free software for calculating bolt circles and similar: Click Here


        • #5
          Enco has a mechanical counter for under $5.00 in their new catalog.
          Location: North Central Texas


          • #6
            be helpful to know if the revs are from a dremel tool a 20K RPM or a sugar cane mill pulled by the old gray mare at i rev per minute (when fresh- gets slower as day progresses). Old tachometers used a stop watch and rev counter to calculate rpm. Just press spindle to shaft and read off.


            • #7
              I cant believe how vague I was, sorry... am counting revolutions (total, not per. min.) while cranking a cord making machine that I built/assembled. the problem is that I have to wind the crank 170 times, somewhere between 120-150 the phone rings, the old ladey takes a swing or whatever and I loose count, I would switch to some sort of electric drive, but just havn't gotten that far yet. thanks for the help so far.

              do you have some sort of number for that enco item?



              • #8
                Enco part # 840-1610, $4.43. 5 digit ratchet counter. If you can do it manually, just get a little push button counter from wall-mart or a sporting goods store, very cheap and easy.
                Location: North Central Texas


                • #9
                  I saw a neat one made from a calculator. enter a #1, You hit the add button each time you want to put in a count. total count displayed. Electro- or mechanical same device.


                  (vague huh?)

                  Well the device I was talking about was a small robot, to program it you had to enter the number of steps each way, the calculator had two wires soldered to the add button and a no switch made each time the wheel turned.

                  You can set a mechanical lever to make the factory switch or electrical contacts.

                  [This message has been edited by ibewgypsie (edited 12-31-2003).]


                  • #10
                    If it only happens occasionally, maybe a cord tied to the shaft. one turn= ONE WRAP on shaft. If you chucked the shaft in a lathe and let the lathe do the work, you can measure turns with a dial indicator: Ie set up for tpi threads, and 17 inches is 170 turns.

                    Yeah Thrud, I don't have a 17 inch DI either- so put a stop at one end and let the carriage come down to the DI at the other end. . Gonna be mid 70, sunny, no bugs til 4 january- bring a 6 pack and a few sets of underwear.


                    • #11
                      I believe one of our host magazines had an article on building your own revolution counter a couple of years back.

                      Paul A.
                      Paul A.
                      SE Texas

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


                      • #12
                        thankyou gentlmen.. er um "guys"

                        thanks for the info, I have been wanting to get a handbook for a while now, the one I paged through once looked very informative. I just have been useing the sherline book and and a few of the photo copied pages that came with some of the attachments. ... ordered a little unit from enco like Joel suggested. dont know when it will get here though.

                        thanks again for all your help



                        • #13
                          When I was winding some small coils a while back I made up a simple counter. I looked at the circuit board and its just one opamp, one IR send/receive device and one flat 5-digit counter display, with a few resistors thrown in at the right places.

                          I set it under a revolving thingummy with a bit of reflective foil stuck on and, well, it counts. Any electronics hobbyist would put one together, if you can find one. Useful thing to have. I'd buy one too, if I saw one.
                          Richard - SW London, UK, EU.


                          • #14
                            Redlion used to make a counter, was about $25, battery powered and smaller then a watch. used all kinds of inputs including switches

                            I bet they are surplus now.