Chuck RPM counter

i would like to make and fit a simple RPM counter to the ML4. Yes I know I could work out the RPM from the pulley sizes and the motor speed and make up a bit of paper with it all written, but where's the fun in that😀 It is a VERY long time since I constructed anything electronic so I'm sure the electronic hardware has changed and I keep seeing references to Arduino, would that be a route to go as I'm happy to learn new stuff as I go along and I'm certain skills learned will be transferable. Thoughts and advice would be welcome please 😀

A cheap model aircraft tachometer should do that , make the chuck sides black and then stick on a piece of reflective foil. In fact two at 180 degrees most props have 2 blades!

I think I paid less than a tenner for the tachometer and you can always use it for what it was sold for!

Andrew

If you want to build a tachometer yourself there is a design on my website that might meet your needs. It can be set to cope with between 1 and 99 pulses per revolution so you can probably pick up pulses fron the teeth on an existing gear on the spindle using a hall effect gear tooth sensor. This is a link to the design. If you google DIY tachometer or rev counter you will find many designs.

Les.

There are plenty for sale on eBay including a hall sensor for around £10. Doesn't give you the satisfaction of making one but very cheap.

Mike

I fitted one of these eBay revcounters rather than make one. It works perfectly and is cheap!

Mike beat me to it!!

Andy

Edited By Andrew Holdaway on 11/07/2017 22:13:04

If you want to make one like Les's but based on Arduino pm me your e-mail and I'll send info on the one I made. Arduino is easier to program. Beware refective opto switches. I found both black and white gloss paint to be equally good at reflecting, even blackboard paint reflects with a thin film of oil. Hall effect more reliable, or slotted opto if you can get it in.

Les, I tried to get info on the Allegro sensor part numbers you quote but got nowhere. Do you have a link?

Edited By duncan webster on 11/07/2017 22:26:04

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I have one of these. Power supply is made from an old phone charger.

Nick

I bought a small battery operated point and shoot tachometer off eBay for about $10. Stick a bit of reflective tape on the chuck and aim the device at it while in motion. Did it for all speeds and wrote them on the wall in felt pen. Haven't seen the tachometer since.

Hi Duncan,
I bought mine from Farnell but las time I looked they no longer listed them. Last November (Nov 16) I found a source of the three wire version which is simpler to interface than the two wire version on ebay. The part number is ATS667LSGTN This is a link to the data sheet. (I paid £3,88 each for them on ebay)

Les.

I checked the rpm on my Chinese lathe at zero cost as I had some threaded rod on stock. I chucked the longest length practicable in the lathe and then measured and marked a known length on it. I then positioned a nut at the end mark and turned the lathe on whilst holding the nut. The time taken to traverse the marks on the threaded rod was then used, knowing the pitch of the thread, was used to calculate the rpm. I did this for all the speeds and made a chart that I hung on the wall. It was remarkably easy to do. The timing was also repeatable.

It was a very long time ago so I can't remember any of the details. 

Edited By ANDY CAWLEY on 12/07/2017 09:03:43

I use this one on my EMCO V10 - from Banggood - it works well and has a nice large 7 seg display.

Joe

Shipping was quick, and Paypal works fine..

**LINK**

I'v used a cheap($NZ2) cycle speedo/computer, I also used it on my hot air motors, until I got one of those non contact laser taccos. The reading from both were very similar, just more convenient not having to fit a magnet to every thing.

Ian S C