Tachometer

[Dave Lehnert]

Is there such a thing as an usable inexpensive tachometer? I would like to have one to check the speed of a Shopsmith among other things.
Anything like a dial type that you can hook to a shaft, Kinda like a speedometer we had as kids hooked to our bikes?
How does an auto tach work? can one be rigged to a tool like a lathe or the like?

[Lee Schierer]

It depends upon what you call cheap. You can get a tachometer (contact or non-contact type) for between $200 and $500. ou might also be able to get a bycycle speedometer like my cateye micro (about 10 years old) that records pedal rpm based on a magnet passing by the pickup head. It may not have enough digits for what you need though. McMaster Carr has several regular tachometers, but I am sure there are other sources.

[Josiah Bartlett]

http://www.harborfreight.com/cpi/cta...emnumber=41727

How about $49.95? Seems cheap enough to me. Probably accurate enough for your use.

[Dave Lehnert]

http://www.harborfreight.com/cpi/cta...emnumber=41727

How about $49.95? Seems cheap enough to me. Probably accurate enough for your use.

Thats more like it $$$$ Any experience with this unit?

[Wes Bischel]

Dave,
You could go old school with a speed indicator:
http://www.gilai.com/scripts/more/to...Misc.-yes.html
This tool and a watch with a second hand. Simple, reliable, and can be had inexpensively on eBay.

FWIW,
Wes

[Wilbur Pan]

I got a cheap laser tachometer off of eBay for about $30. It's pretty easy to find -- just search for "laser tachometer" on eBay. I used it to figure out the true speeds on my lathe.

[Dave Lehnert]

Dave,
You could go old school with a speed indicator:
http://www.gilai.com/scripts/more/to...Misc.-yes.html
This tool and a watch with a second hand. Simple, reliable, and can be had inexpensively on eBay.

FWIW,
Wes

Wow! That is interesting. How does it work?

[Michael Faurot]

Wow! That is interesting. How does it work?

I've not used one myself, but a friend had one similar to that. From the way my friend explained it, the idea is to touch/connect the shaft of the speed indicator to the spinning thing you want to measure, and then run it for sixty seconds (i.e., one minute). After one minute look at the dial on the speed indicator and that will tell you the RPM.

[Steve Rozmiarek]

Wow! That is interesting. How does it work?

Dave, I'll strongly second the Starrett tach. They are such a simple little thing, and accurate. Really is a rotation counter, count the revs in 60 sec, and you have rpm. As machines don't change rpm once set, this is a really cheap and accurate way to set up your tools. I've bought a few off ebay and at farm auctions, never paid more then $10.

[Wes Bischel]

Michael and Steve explained it well. I have an ancient Craftsman that you have to multiply the readings by 100 to get the RPMs. I hold my finger over the 0/100 mark to feel each time the dimple goes by. That lets me keep my eye on the watch.
I like it because it's "anvil technology" (a phrase used often by a friend) stupid simple and unpretentious.

There are always a few on eBay.

Wes

[james gerus]

The laser tach uses the light reflecting off the rotating shaft to measure RPM. You tape off part of shaft surface so the tach gets a "pulse" of light to count. Jim Gerus

[Frank Townend]

As with Wilbur I bought one from eBay. It came with a fair amount of reflective tape. I measure my lathe, drill press, portable drill, band saw, my cats; you name it.

[Steve Rozmiarek]

As with Wilbur I bought one from eBay. It came with a fair amount of reflective tape. I measure my lathe, drill press, portable drill, band saw, my cats; you name it.

Your cats?! Thats funny!

[Frank Townend]

Thanks Steve. Fast little suckers come dinner time.

[Karl Brogger]

Check a hobby store. A long time ago when I was into RC airplanes I remember seeing a tach of some sort that worked optically.