In the workshop, there are sometimes old machines where no one knows how quickly the turn. If one is not to fly around the ears, the new grinding wheel is so popular measure.
1. First attempt: the bare metal shaft a dark piece of tape, metal reflects but also ?!
--- Measuring results are junk, the bare metal reflects everything nix correctly or is measurable ...
2. Second attempt: 2cm with reflective tape (incidentally sticks like poison) result 3000 r / min +/- 1, makes sense in a bench grinder
3. Third attempt lathe: Result: The measured speed is usually 7-8% higher than the set speed ...
Conclusion:
If you only need a house number, whether 2000 or 5000 is not a problem!
Who checked the old record player wants if there are still 33.3 revolutions for LP .... LOL ... wrong price category
