baja (Mar 11, 2021), ColWA (Feb 17, 2019), FEM2008 (Mar 10, 2021), high-side (Feb 11, 2019), Jon (Feb 12, 2019), Ken Koch (Feb 12, 2019), odd one (Mar 10, 2021), Paul Jones (Feb 9, 2019), PJs (Feb 13, 2019), rossbotics (Feb 10, 2019), Tonyg (Feb 12, 2019), Toolmaker51 (Feb 11, 2019), Tule (Feb 12, 2019), UncleBob (Feb 17, 2019)
I purchased a Thai made bicycle speedometer for my band saw several years ago and mounted that on the top wheel. Using a formula I found somewhere like this forum I set it to read blade speed in metres per second tho it could also be set to read rpm or fpm. I may still have the setup instructions and formula if you need them.
I should have been smart and kept it when I replaced that bandsaw.
I think you could probably find a suitable location for the small magnet that provided the pulse AND the peanut sized sensor so that it would read chuck rpm
Captainleeward (Feb 12, 2019), Toolmaker51 (Feb 11, 2019)
So much TO LEARN! Apparently, I need to add electronics to curriculum. That a speedometer could interpret as FPM is like made to order. I'd recommend posting the setup and formula an individual thread. Sure to be appreciated by many.
Sincerely,
Toolmaker51
...we'll learn more by wandering than searching...
Here is one that I got, UK eBay but I am sure that the US eBay has them too. I was going to make my own but at that price that would have been folly beyond imagination. ebay tacho
Here is a pic from the listing
You need no knowledge of electronics, it will measure the rpm of whatever device you put the pickup on.
high-side (Apr 5, 2019)
I'm assuming "FPM" is a typo and you meant RPM.
Firm proof that one can find the answer to anything on the web. (Well, at least stuff that has an answer. "Meaning of life" and such questions are referred to the religious shamans.)
https://www.instructables.com/id/Tac...ometer-cycloc/
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Regards, Marv
Failure is just success in progress
That looks about right - Mediocrates
Toolmaker51 (Feb 12, 2019)
PJs (Feb 13, 2019)
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.
Last edited by tonyfoale; Feb 13, 2019 at 02:29 AM.
Captainleeward (Feb 13, 2019), DIYer (Feb 14, 2019), Toolmaker51 (Feb 13, 2019)
Thanks Captainleeward! We've added your Lathe Tachometer to our Measuring and Marking category,
as well as to your builder page: Captainleeward's Homemade Tools. Your receipt:
New plans added on 11/20: Click here for 2,589 plans for homemade tools.
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