Dumb ? of the day

[mikern]

I recently got a FM 6/1, was wondering if anyone there could tell me HOW to measure the RPM when it is running? thanks in advance, Mikern

[Doug]

You need a tac....

But if you listen to the speed of some of the engines people around here have clips of you can get an Idea of how fast is normal VS too fast.

Not much hlep but its free advice

Doug

[Rtqii]

http://www.multimeterwarehouse.com/tahcometer.htm

^^^ Contact tachometer is the direct solution. You hold the tach head to the end of the shaft and read the speed on the display. I have seen old ones that were mechanical with a dial indicator, hard to find these days.

The other option if you are generating is to put a frequency meter on the generator output. The frequency will directly correspond to the engine RPM, just calculate crankshaft speed based on your pulley diameters.

[Andre Blanchard]

Some pics of what you should look for. 
http://www.prestonservices.co.uk/counters.htm
http://www.steamengine.com.au/ic/faq/rpm.html

[bat outta hell]

Hello Guys
Stewart Warner still makes the hand held tach. Do a google search to find a dealer.

regards
bat

[sid]

also napa still sell them new..700-1064   $91.99// the rubber tip are usually broke or missing.. they are availavle from napa 700-9570//$2.49//sid

[hotater]

I just found a laser reading tach on ebay for $9.95.  660 RPM is what I got...

[mikern]

Thanks guys for all the suggenstions, think I'll look for that laser tach on ebay too. Mikern

[slowspeed1953]

Programable bicycle speedometer about 10$-15$ on ebay.

Strip a one inch area on the inner flywheel rim of the paint and epoxy a tiny magnet onto the inside rim of the flywheel @ 23" diameter repaint the area and set the bike speedo to 23".

Every 14.62 rpm will equal 1 mph. So at 650rpm the bike speedo will read 44.45 mph.

Peace&Love , Darren

[Andre Blanchard]

Programable bicycle speedometer about 10$-15$ on ebay.

Strip a one inch area on the inner flywheel rim of the paint and epoxy a tiny magnet onto the inside rim of the flywheel @ 23" diameter repaint the area and set the bike speedo to 23".

Every 14.62 rpm will equal 1 mph. So at 650rpm the bike speedo will read 44.45 mph.

Peace&Love , Darren

The ones I have seen are programmed by setting the wheel circumference in mm.  If you calibrate it at a circumference of 2682mm then 100rpm will display as 10.0mph, it will display up to 99.9mph or in our case 999rpm.  And they have an odometer that reads up to 9999.9 miles before rollover.
If you take the number off the odometer and multiply it by 600 you get the number of revolutions the wheel has made, so it will count up and rollover at 6000000 revolutions.  At 650rpm this would be 153.8 hours which if you average 4 hours of runtime per day would be 38 days.  If the odometer reading is multiplied by 0.0154 you will directly get hours of runtime.

But they are not the most rugged of devices.

[Twinscrew]

Programable bicycle speedometer about 10$-15$ on ebay.

Good call Darren. The Cat Eye that I run on my bicycle logs not only distance, but also trip times and total time. Can you say cheap and accurate hour clock? Knew ya could.

[Firebrick]

http://www.tinytach.com/tinytach/diesel.php

Made for this application, not to expensive either.  I havent used the diesel version but have used the original tinytach, I though it was pretty good stuff.

[BruceM]

An optical tachometer for model airplanes also works. Set it for a 3 bladed prop, point through the spokes towards daylight or a DC flashlight (not AC lighting).  1300 rpm will be indicated for 650 actual.