R.P.M Lathe meter mod.

[tonyfoale]

Yes, in a roundabout way. Response [post #3] led me believe the 'program' functioned in conversion RPM & wheel diameter to FPM. To date, all the bandsaw FPM gauges I've seen are cable driven analog

Your first interpretation of that post was correct. The bicycle speedos allow the input of the bicycle wheel diameter, so by adjusting the input diameter you can alter the displayed reading for a given RPM of the thing being measured (within the range of acceptable input values). As the m/s value (or FPM) is directly proportional to the RPM of the bandsaw wheel it is only necessary to fudge the input wheel diameter for the readout to be in appropriate linear units. That is a trivial calculation. If the calculated fudged diameter is below what the bicycle speedo accepts then you can fudge the reading by integer multiples by the simple expedient of getting multiple pulses from each rev of the band saw wheel.

The above only applies to the use of the bicycle speedos (mentioned in post 3) or other tachos which allow for a method of calibration. IT DOES NOT APPLY to the type of tacho shown in the first post. These have no calibration or adjustment features, they are made to display RPM based on a single pulse per rev.

However, it would be a simple project to put an Arduino or similar micro between the pickup and display, programmed to convert the pulse rate into a linear measure which could be made m/s or FPM at the press of a button or flick of a switch. The programme (confusingly called a sketch in Arduino speak) could have the bandsaw wheel diameter hard coded before being downloaded from a PC. That would keep the programming simple but would mean that minor software changes would be needed for each wheel diameter or there are various ways to set it up to accept the diameter data via controls on the device itself, like programming a VFD or setting the time on a digital clock. The Arduino programming would be more complex in that case.