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Starrett RPM Counter Tip

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  • Starrett RPM Counter Tip

    Click image for larger version  Name:	Starrett RPM.jpg Views:	0 Size:	36.3 KB ID:	1850979
    Anyone have experience replacing the rubber tip on an antique Starrett revolution Counter?
    New Old Stock would be rare as​ well as hard as a rock like mine.

  • #2
    Piece of rubber tubing cut square should work. Mine is not a Starrett, but that is what it has
    CNC machines only go through the motions

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    • #3
      Whats the shaft diameter? Sure looks like a rubber eraser tip for a pencil. Wonder if one would fit

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      • #4
        I made one from a cut-off from a hockey puck - really hard rubber that doesn't deflect.

        Geoff

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        • #5
          The number of miles flown by those tips and manhours spent looking for them are beyond calculation.
          If you're planning to use the tool, plastcs work so much better. For display, whittle one out of hard rubber.

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          • #6
            You guys make this forum great. Responding quickly with information that will greatly help me. THANK YOU!
            Click image for larger version

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            I am upping my game with this 1921 South Bend 9" Junior. I've added a quick change tool post and am
            exploring carbide and ceramic tooling.The drive system is a motor cone pulley driving an intermediate jack
            shaft with a cone pulley and a flat belt pulley. I need to know chuck rpm. The revolution counter
            tip is already cracked. Thanks to you I have options if / when it fails.

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            • #7
              I have one of those rev counters and find it useful from time to time. So far the tip is holding up.
              A couple of comments on the lathe. I can't make out the driven cone pulley but if it is anywhere near a matching size of the one on the motor you are going to have a very fast range of speeds. I do see what looks to be a large single groove pulley on the left end of the intermediate shaft but it isn't lined up with the motor. Also you might want to visit the baking dept and get a large shallow pan for chips to fall into. There must be some hidden frame work behind the lathe that you could add to to support the pan.

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              • #8
                You really do not need a tach for that.

                You know the motor rpm, which is on the motor tag. just go through the 6 speeds, and for each one, count the motor turns for one turn of the spindle. That gives you the ratio, so if the motor turns 5 times per spindle turn, the spindle speed is the motor rpm / 5. If the motor is a 1725 rpm motor, then you can just divide (in this example) 1725 by 5, giving 325 rpm.

                Put in in back gear, and check how much more the speed is reduced, which is typically by 5 or 6 times. That is constant for any speed, so the back gear speeds are less than the regular speeds by that ratio.

                The motor is a constant speed, so this will let you develop a table of speeds that is easily close enough for all practical purposes.

                With that machine, carbide will be fine, no need for ceramic. The power and speed are just not enough to use ceramic effectively, carbide will be all you need, and is easily available.
                CNC machines only go through the motions

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                • #9
                  wdtom you are correct. My description was not right.
                  So there are four speeds with the two similar v-belt
                  pulleys and three more with the two flat belt pulleys
                  giving twelve speeds. Twelve more with the back gear.

                  J Tiers is also correct. The simple solution would be
                  to calculate the fastest speed and slowest speed.
                  The rest of the rpm's would be along a straight line
                  graph between them. But, which endeavor will be
                  the most fun?

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                  • #10
                    Here is what I do and other clever machinists do.. check the real rpm on the machines, with a Starrett revcounter or a direct reading counter. And I write it down. ON the machine or beside it...now I can choose proper tool for the next operation and machine efficiently..
                    Last edited by 754; 01-25-2020, 02:30 PM.

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                    • #11
                      That conehead machine does not have pulleys, it has sheaves and a jackshaft and the machine will appreciate proper reference to them. South Bends operate on pride.
                      The chip pan hangs from 2 bars sitting between the bottom of the rails. The design incorporates the alerting feature of the bar falling out and making noise to alert the operator he failed to put the chip pan back in place.

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                      • #12
                        OK, fun is fun. If ya wanna , yah wanna.

                        But pretty much nothing that gets done will be so critical as to need even the speed within 15% or 20%, if even that close.

                        If it is that critical, maybe something is being over-thought.....
                        CNC machines only go through the motions

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                        • #13
                          Starrett DOES answer phone calls. Have you tried talking to them? Perhaps they have NEW stock or may even make it if requested.
                          Paul A.
                          SE Texas

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

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                          • #14
                            Franz, Perhaps minor inaccuracies are due to the
                            cheap plastic chip tray on the floor under the lathe.
                            Any South Bend deserves better.

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                            • #15
                              Originally posted by Franz© View Post
                              That conehead machine does not have pulleys, it has sheaves and a jackshaft and the machine will appreciate proper reference to them. .
                              you sure? I always thought they were pulleys. Sheaves are the grooved things in a block and tackle and whats in a cone head is a pulley.
                              Last edited by Mcgyver; 01-25-2020, 09:48 PM.
                              in Toronto Ontario - where are you?

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