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Digital tachometer for checking RPM?

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  • Digital tachometer for checking RPM?

    Do any of you have or use a digital hand held tach for measuring the RPM of different things around the shop/house? I need one to check the speed of my drill, of my routers and other things at times. I remember digital tachs that read the speed of RC/model airplane engines back in the 70's but never bought one.

    I am looking for a tach that can give at least an approximate speed of the router and my drill press. But I don't want one that you have to add tape to in order for it to determine the speed. How can you get tape to stick to a 25,000 RPM router bit?

    So what kind of tacos are available that can check the speed of routers and drill press heads?

    Thanks
    Hank Lee

    Experience is what you get when you don't get what you wanted!

  • #2
    Yeah, I've got one.

    Those $22 tachs (like Nieko) on eBay work great. Amazon for $19.99 Prime shipping. Yes, you have to use reflective tape, but I cut off about 3/8" square piece and just stick it on the on one of the flats of the collet nut. I've wrenched on it many times and its still intact. It takes a very small piece of tape. I'm sure even smaller would do.

    There's very little centrifugal force to throw it off because the mass of the bit of tape is tiny even at 25K RPM. Fear not.

    They have crystal controlled timebases so they are very accurate. I measured the old style mag ballast Fluorescent tubes (point it at the tube, no reflective tape needed since the bulb is an emitter) and they said 7200 RPM pretty much right on the nose and I know the power line frequency is very well controlled. 60 Hz = 3600 RPM and the bulb lights twice per cycle.

    You have an irrational fear of reflective tape. Go for it! You'll be happy with it.
    https://www.ebay.com/itm/Neiko-20713...C6qI:rk:8f:0

    https://www.amazon.com/Neiko-20713A-Digital-Tachometer-Contact/dp/B000I5LDVC/ref=sr_1_3?ie=UTF8&qid=1546414500&sr=8-3&keywords=neiko+digital+tachometer







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    Your other choice is a similar one with both a contact probe and non contact sensing. Now having that probe spin at 25K RPM is scary and the thing costs $117 at Amazon. and is really the same device electronically except a rotor is provided at the front to press against the center of the rotating shaft. Much less convenient/safe/easy to use.
    https://www.amazon.com/REED-Instrume...chometer&psc=1
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    Attached Files
    Last edited by LCHIEN; 01-02-2019, 04:24 AM.
    Loring in Katy, TX USA
    If your only tool is a hammer, you tend to treat all problems as if they were nails.
    BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

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    • #3
      Here's pics of the reflective tape mounted on a cordless screwdriver and a 1/2" Bosch 1617 collet.. I'm sure these have been there at least 5 years each with no signs of falling off or being worn out. Like I said, smaller would probably work fine as well.

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      Attached Files
      Last edited by LCHIEN; 01-02-2019, 04:37 AM.
      Loring in Katy, TX USA
      If your only tool is a hammer, you tend to treat all problems as if they were nails.
      BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

      Comment


      • #4
        Thanks Loring. I was skeptical of tape, but if it stays put as yours has - that would do well. I bought an MLC HD router speed controller to use on my 2 hp router for making a raised panel set. The speed controller works but I would like to know the speed that it is turning and be able to adjust it as needed.

        Thanks; this is very helpful.
        Hank Lee

        Experience is what you get when you don't get what you wanted!

        Comment


        • #5
          Here's two sawdustzone threads you should read

          https://www.sawdustzone.org/forum/di...eed+tachometer

          https://www.sawdustzone.org/forum/di...eed-controller

          Evidently the tape has been on my router for 11 years now and still hasn't fallen off.

          Also the speed controller pictured in the second link is still widely available on Amazon from multiple sellers and on ebay for prices down below $16. They all look exactly the same; some have a logo on the front, and some are listed as fan speed controllers and some as router speed controllers but they are all the same. The specs are all the same, 15 Amps, 120 VAC.
          I'd just shop for lowest shipped price.
          That's all you need.

          Last edited by LCHIEN; 01-02-2019, 02:23 PM.
          Loring in Katy, TX USA
          If your only tool is a hammer, you tend to treat all problems as if they were nails.
          BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

          Comment


          • #6
            I have been thinking of picking one up but I don't have a real need so it would be more of a fun toy. From what I've seen online they work well and are accurate but you have to be careful because depending on what it picks up it can sometimes be off by a multiple (e.g. it senses 2x per revolution and thus the speeds are half the reported value)

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            • #7
              Originally posted by tfischer View Post
              I have been thinking of picking one up but I don't have a real need so it would be more of a fun toy. From what I've seen online they work well and are accurate but you have to be careful because depending on what it picks up it can sometimes be off by a multiple (e.g. it senses 2x per revolution and thus the speeds are half the reported value)
              Generally you have to be careful and not measure where there are repeating patterns such as spokes. You should put your reflective tape on the solid part of a wheel that will not be varying as it rotates. THen I think you won't have any problem.
              Loring in Katy, TX USA
              If your only tool is a hammer, you tend to treat all problems as if they were nails.
              BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

              Comment


              • #8
                Thanks Loring. That was a couple of good posts. I thought there had been a post on VS for routers before.
                Hank Lee

                Experience is what you get when you don't get what you wanted!

                Comment


                • #9
                  Originally posted by leehljp View Post
                  Thanks Loring. That was a couple of good posts. I thought there had been a post on VS for routers before.
                  Here's a better picture of the tape on the collet with 11 years of wear and tear. I was embarrassed by all the sawdust on it in the previous picture.

                  Click image for larger version

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                  Loring in Katy, TX USA
                  If your only tool is a hammer, you tend to treat all problems as if they were nails.
                  BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

                  Comment


                  • #10
                    I ordered one from Amazon and got it yesterday. I had one initial problem, the LED was way out of alignment and was not shining directly outward. it was shining on the inside of the shroud and dispersing upwards. I slapped it lightly a couple of times in my hand and the light moved into position but it was not directly out but it did have a full beam. I tapped it a couple of times again and it went back into position with the LED laser shooting out directly in the middle of the nose cone. Did some tests on my drill and on my router with the speed control - and it was working correctly. I knew the no-load speed of my Ryobi 18V drill and the readout was right on it. The I tried the tach on the PC 690 plugged into the speed control 26000 (IIRC) for full speed and 9,900 on slow, with intermediate speeds.

                    I now need to take it apart and make sure the Tach's laser is locked in place. when I do, I will weigh the options for locking it in place - some kind of glue, a dab of hot glue or other. It has a good bag to keep it in.

                    Thanks Loring for your help.
                    Hank Lee

                    Experience is what you get when you don't get what you wanted!

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