Universal, inexpensive tachometer

[Spidybot]

Just saw this $49 tach:<br />

<br /><br />Needs a free view of a rotating part (like flywheel) to work and measures rpm on any engine, motor or other moving device. No wires, leads or sensors.<br /><br />Great when checking rpm for prop selection on boats without a permanent tach.<br /><br />Don't know how many shops sell this device, just happened to see it on www.circuitspecialists.com<br /><br />Denmark/Sweden/Norway/Finland can get it from Biltema.

 

[JB]

Re: Universal, inexpensive tachometer

Waaaay cool, UU! <br /><br />My guess is that the red line is a laser beam, not an antenna.<br /><br />That's an "everybody's tool box" item if I ever saw one.

 

[TwoBallScrewBall]

Re: Universal, inexpensive tachometer

These work great, however, they are designed for uses like a propeller where there will be breaks in the rotating item. I use one for my model airplanes to check wot rpm and adjust the mixture accordingly. If you point it at a flywheel or any other solid rotating item, it had no way to 'count' rotations since the laser beam never sees any difference in the wheel (or pulley or harmonic balancer, etc) as it rotates. Pointing at a prop, or fan blade, etc, the laser sees the blade, then sees air, then sees the blade, etc, so it can count revs. <br /><br /><br />What's cool is that if you point these at a flourescent light it will tell you it is 'spinning' at 3600RPM, since the flourescents flash on and off 60 times a second (in the USA). <br /><br />Unless this one operates differently from the ones I have had experience with, it won't work pointing at a flywheel or any other solid rotating object.

 

[TwoBallScrewBall]

Re: Universal, inexpensive tachometer

I stand corrected (I think) as this one is a bit different from the ones I'm used to, and seems like it comes with a supply of "reflective sheets" to stick on the part to be checked. Pretty cool.

 

[JB]

Re: Universal, inexpensive tachometer

My guess is that they work if you just use a marker to put a line of the flywheel. Some things spin so fast that even a piece of tape can throw them out of balance.

 

[gaugeguy]

Re: Universal, inexpensive tachometer

I have one that is similar, made by Pioneer. With mine you stick a piece of reflective tape on the flywheel(or whatever), and point and shoot.<br />It's a pretty handy little tool.

 

[Spidybot]

Re: Universal, inexpensive tachometer

Yes, JB - sorry I did not state that at first: The red line is only an idication of a laser beam going out. Here's a clearer pic:<br />

<br />The thing comes with selfaddhesive reflective tags (guess it'll work on any reflective material). It simply counts the number of passes and calculates from there.<br /><br />It even stores the number of revs., so if you know you need to turn a certain thing (i.e. a reel) a number of times, it'll show it.

 

[PatPatterson]

Re: Universal, inexpensive tachometer

Pretty Slick. I've also worked with strobe tachs that will work on flywheels or smooth surfaces. Just point the strobe at the spinning surface, and adjust the speed of the flash until it appears to be standing still, and you have your RPM. This one is much less expensive, and appears to be able to perform the same function.

 

[skeezx01]

Re: Universal, inexpensive tachometer

we had something similar at tech school. when you run out of the reflective tape a mark with plain old black board chalk works fine and is cheap to boot.