Thread: Tachometer
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Unread 08-11-2004, 04:02
Alan Ing Alan Ing is offline
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Re: Tachometer
Harbor Freight has a non contact photo tachometer. It cost $69.99. I bought one a couple of years back. I used it to confirm the freeload speed of the motors with and without our transmission. Easy to use. Your supposed to use some reflective tape and just point the tach at it. But you can also use black tape or white tape just as long as you make sure only one portion of the area on the shaft/wheel your measuring is reflective. It was interesting to confirm that drill motors do indeed spin slower in reverse.

Your school may already have a measuring device. See if the Physics teacher has a strobescope. Its a little harder to use, but you just mark a spot on the shaft or make a small flag out of tape and turn it on. Just vary the frequency of the strobe so that your mark or tape flag looks stationary and read off the frequency which will also be the rpm. Nice thing about this is that its also non contact. Just watch out for harmonics as they can give you a false reading.