Tool RPM Measurement

[Bill Adamsen]

What experience do folks have with measuring rpm ... preferably in a static setup? I'm looking at some options like the "cheapo" Hall proximity switches ... or the bicycle wireless cadence computers like the Sigmas. The ability to translate to a velocity in fpm would be nice, along with total distance.

[Mike Heidrick]

I use a digital non contact photo tachometer - google those. About $15-$20.

[Bill Adamsen]

$16 delivered ... order placed. Thanks!

[Mike Heidrick]

They work to at least 24000rpm.

[Fitzhugh Freeman]

Since you mentioned a static setup I figure I'll put in my 1/16 cent.

I went with one of the cheap 4 digit hall sensor types off eBay. "4 digit red LED tachometer RPM..." is how it was listed, just under $15 with shipping, i assume, by trained sea turtle since it was quite quickly mailed but took a few weeks to arrive from China (not actually complaining since it was within the stated delivery time).

The one I got did not come with instructions but really didn't need any. There is a set of wires with a plug on one end for a socket on the board and two bare ends for power, I have an old 9v wall wart to use but have been using a 9v battery for now. Do make sure you get one with the sensor, as there are some that look the same but do not include one (the one I saw that said it had a pre-scale function does not seem to include a sensor).

This allows a mounted and hands free tach on one machine but would be a pain to use if you do not want it mounted, a good pair with the optical type.
I did see a YouTube video mention they eat batteries quickly if forgotten, hence adding a transformer.

Lastly, they require the magnet face the right way. If backward it won't read. A small point but I thought I had a dud for a minute