Tachometer

[JPG]

Both 'answers' still beg the question 'why'(does it matter).

[edma194]

Both 'answers' still beg the question 'why'(does it matter).

Because the one who dies with the most tools wins!

Well, I guess you mean "Why does it matter how close the speed dial matches the actual speed?" For me it's mainly curiosity. When I installed my PowerPro I used a phone app to check the speed just to find if it matched what the control panel said. The app was only good enough to tell me it was in the neighborhood. If I'm repairing or refurbing a machine I'd like to be able to check that and any other tool to see if it matches the spec.

[Ash1562]

JPG - the 'why' to a lot of what we woodworking, shopsmith-obsessed folks is probably best left unasked. My wife asks me this 'why' a lot and I just smile back. Curiosity is the best answer, as stated.

For the magnets, I use: https://www.amazon.com/Strongest-Neodym ... B06WGMRDHS

[lahola1]

"Both 'answers' still beg the question 'why'(does it matter)."

For me the act. speed isn't that important. It's learning, experimenting and playing with the Arduino.

[garys]

I want a tachometer because I don't have one. That's a good reason to acquire any tool.

I'm not really fond of "owning" tools. I like "using" tools. If a tool here isn't racking up lots of hours, it isn't worth buying. My Shopsmith is rolling up around 15 hours a week this Winter, and that makes it a keeper. There are a lot of tools I don't have, and don't want taking up space in the shop if they aren't going to get heavy use.

[rpd]

I might play around with the Arduino approach. I want something more of a stand alone tach and was thinking about something that could pick up a reflected light instead of a magnet so anything could be tested with just a little stick on foil dot. The circuit is simple enough either way. I wonder how light weight the magnet could be to trigger those Hall Effect sensors at high speed. If it was light enough it could be stuck on just like a reflective dot.

One thing to consider in light v magnetic sensors is the dusty environment they are operating in. The PowerPro motors can have problems if the sensor is obscured by fine dust. Magnets do not have this problem. ;

[Ash1562]

RPD - you read my mind as this is an exceptionally good point

The other guiding principle I enjoy is to _not_ clutter up your shop with one-use tools. The Shopsmith itself is the epitome of that principle. To me, so is the arduino! You can use it as a techometer, digital level sensor, temperature/humidity monitor, multimeter, etc.

[edma194]

One thing to consider in light v magnetic sensors is the dusty environment they are operating in. The PowerPro motors can have problems if the sensor is obscured by fine dust. Magnets do not have this problem. ;

Well yes, but the PowerPro control panel shows the current speed when it's running. I'm just looking for something to spot check other tools, like making sure I chose the right pulleys to get the grinding wheel spinning at the right speed. It would be pretty easy to check the PowerPro with a magnet once in a while with a magnet tach, just stick the magnet on a sanding disk and compare the tach to the control panel. But there are a lot of rotating pieces that are small like a 1/2" shaft, or not made of steel and the magnet has to be glued on.

I suppose if I do make one based on either a Hall Effect switch or a photo sensor I should just add the components to do it the other way also. If I'm lucky I could just swap out detachable cords with the different sensors that produce the similar enough signals. I have an Arduino kit I didn't end up doing anything permanent with, I'll look for some components and maybe it will happen some day.