How to Determine RPM of Compressor Shaft

http://www.fastcharged.org/electronics/handyrpm

http://www.jeffree.co.uk/Pages/speedmeasurement.html

Nope, I haven't the foggiest idea how to measure or display your compressor shaft rotation. I've searched three times for an "onour machine", an "honor machine" and even an "honour machine" but have not found anything that resembles a compressor. So I have no idea what your compressor looks like or the environment and room you have for instrumentation. For all I know your compressor could be a scroll compressor for a refrigerator, a roots type compressor for an intake manifold, a reciprocating piston compressor for compressed air or any of the myriad of ways that humanity will compress something.

Now along with the optical method that kramarat provided links for, you might also consider attaching a magnet to the shaft and as the magnet pole crosses the windings of a coil the voltage induced will be linearly related to the velocity of the magnet. This will provide an instantaneous measurement instead of an average measurement.

I have no idea what you want, but I do have an idea of what you need.

Tachometer.

Motor rpm times drive ratio.

What isyour machine?

Put a line of white or black paint on the shaft, then use a stroboscope:

http://www.ehow.com/how_5021934_use-strobe-light-measure-rpm.html

Lick your finger, touch it to the spinning shaft using 3.62 lbs of pressure and hold it there for 6 minutes. Then use an infra red scanner to measure the temperature of your finger tip and look up the yards-per-degree-F on the finger tip temperature coefficient of friction chart on page 398 of the infra red scanner manual. Punch that number into your PC and display it in a spreadsheet that converts YPDF to RPM by using the circumference of the shaft divided by the YPDF x the 6 minutes. Note: if using metric values, hold for only 5 minutes because of the 50Hz speed.

The last time I laughed this hard at a CR4 post was when someone asked for help getting a "pneumatic hooter" to work! Thanks, you brightened my day!!!