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Old 09-13-2016, 08:00 AM   #1
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handheld tachometer

I would like to have a handheld tachometer for checking a diesel engine and gasoline inboard and maybe a generator. I would like some type of mechanical device versus electronic. Any suggestions.
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Old 09-13-2016, 08:11 AM   #2
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I would like to have a handheld tachometer for checking a diesel engine and gasoline inboard and maybe a generator. I would like some type of mechanical device versus electronic. Any suggestions.
Interesting. I don't mean to hijack thread and hope you get the handheld mechanical "check-it" tach you seek

But, seeing as our Tolly's starboard tach on flybridge recently stopped working (only one that stopped out of four tachs aboard)... I can't help but wonder if there is a set up that could be added to engines where a sending unit emitted waves to a hand held tach, without any wires or cables at all?? That would be pretty neat!
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Old 09-13-2016, 08:15 AM   #3
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Bought a cheap handheld Noncontact Tach Tool RPM Handheld Digital Photo Laser Tachometer Meter Tester WP | eBay $15 Works fine. I used to check all the tachs on the boat and to set the idles on my Lehmans so I did not have to leave the engine room. Works great. Just stick a shiny piece of tape on the crank pulley.
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Old 09-13-2016, 08:25 AM   #4
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I have used one of these and it works well.

Stewart Warner Hand-Held Tachometers

I own a <$20 electronic one that suits my needs.

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Old 09-13-2016, 11:40 AM   #5
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I don't think you should prefer mechanical. The optical sensor types are amazingly simple (in their design) and accurate. I have used one to make sure that my transmissions don't slip (they don't, not even a little).
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Old 09-13-2016, 12:03 PM   #6
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" I would like some type of mechanical device versus electronic. Any suggestions. "


I have both a mechanical hand tach as well as a 'cheap' laser strobe tach.
IMO the strobe tach is much better in ease of use, accuracy , and safety.


I think it cost me about $25 on amazon about 6-8 years ago and still works great.
Just take the batteries out when not in use.
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Old 09-13-2016, 01:15 PM   #7
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Ran across something called TinyTach, I think that was the name, quite a while ago. It put a clamp on sensor on one of the injector pipes and used the pressure pulses to read RPM.
Not sure if they are still around. Have to google it I guess.
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Old 09-13-2016, 02:27 PM   #8
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I 2nd the photo tach. I keep one on my service truck. they work good as long as you have a spot you can stick the reflective tape to.
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Old 09-13-2016, 07:10 PM   #9
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I 2nd the photo tach. I keep one on my service truck. they work good as long as you have a spot you can stick the reflective tape to.
Actually I have a photo tach and found there are times I cannot get a reflective tape where I need it. That is the reason for wanting to find a manual. Found one on EBay this morning. Will know in a week if it works. A friend's DD 6V92 does not have a place for the tape without taking a major guard off. Lots of trouble. The manual would work well, if this one on EBay works. Thanks to everyone for the responses.
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Old 09-13-2016, 07:44 PM   #10
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"Actually I have a photo tach and found there are times I cannot get a reflective tape where I need it"


FWIW - I have had good results adding readable 'marks' to crank balancers, pulleys and even on the back of the engine on the flex plate 'teeth' with a small paint brush.
Taking a small can of chrome spray paint and spraying in into the can cap I dip the paint brush in and swipe a line in the desired spot - at times I have duck taped the small paint brush on a yard stick to reach in further. After that reading at a distance with the strobe without having to make contact was fairly easy. When used on slave pulleys you just need to know the ratio to do the math.
Good luck with whatever method you use
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Old 09-14-2016, 07:47 AM   #11
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"Actually I have a photo tach and found there are times I cannot get a reflective tape where I need it"

FWIW - I have had good results adding readable 'marks' to crank balancers, pulleys and even on the back of the engine on the flex plate 'teeth' with a small paint brush.
Taking a small can of chrome spray paint and spraying in into the can cap I dip the paint brush in and swipe a line in the desired spot - at times I have duck taped the small paint brush on a yard stick to reach in further. After that reading at a distance with the strobe without having to make contact was fairly easy. When used on slave pulleys you just need to know the ratio to do the math.
Good luck with whatever method you use
Interesting idea. Is it the metalic particles in the paint that makes this work?
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Old 09-14-2016, 10:38 AM   #12
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Interesting idea. Is it the metalic particles in the paint that makes this work?
The sensor just measures reflected light, focused through a lens from a small area and feeds that data to a microprocessor, which just looks for spikes. The differential need not be huge. If your eye can plainly discern the bright spot, so can the sensor, even if it is sensing thousands of times (rpm) per minute.
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Old 09-14-2016, 04:31 PM   #13
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I have used a vibra-tach, especially on small engines but it works on all engines.
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Old 09-14-2016, 05:01 PM   #14
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I have used a vibra-tach, especially on small engines but it works on all engines.
LOL. I still have one of those too. More of a conversation piece than anything else.

Showed it to some of the younger vibe techs. They were amazed.

I also have a mechanical contact tach and a cheapo optical tach.
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Old 09-14-2016, 06:13 PM   #15
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Actually I have a photo tach and found there are times I cannot get a reflective tape where I need it. That is the reason for wanting to find a manual. Found one on EBay this morning. Will know in a week if it works. A friend's DD 6V92 does not have a place for the tape without taking a major guard off. Lots of trouble. The manual would work well, if this one on EBay works. Thanks to everyone for the responses.
You could also drill a hole in the guard for the photo tach. A 1 inch stepped bit should do the trick. Photo tachs are accurate +/- 1 rpm and will work on an angle.
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Old 09-14-2016, 09:26 PM   #16
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Maybe I missed this sort of device recommended in a post... But, what I would like to find is an electronic sending unit that sits on/at the engine and wirelessly activates the receiver in tachs that are both on the bridge and in the salon.


This exist??
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Old 09-15-2016, 12:00 AM   #17
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Maybe I missed this sort of device recommended in a post... But, what I would like to find is an electronic sending unit that sits on/at the engine and wirelessly activates the receiver in tachs that are both on the bridge and in the salon.


This exist??
you can make it easily

arduino
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Old 09-15-2016, 07:53 AM   #18
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you can make it easily

arduino
"Easily" is a pliable word. Please explain or point me toward a net explanation link.


Thanks, Art
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Old 09-15-2016, 09:03 AM   #19
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Quote:
Originally Posted by smitty477 View Post
"Actually I have a photo tach and found there are times I cannot get a reflective tape where I need it"


FWIW - I have had good results adding readable 'marks' to crank balancers, pulleys and even on the back of the engine on the flex plate 'teeth' with a small paint brush.
Taking a small can of chrome spray paint and spraying in into the can cap I dip the paint brush in and swipe a line in the desired spot - at times I have duck taped the small paint brush on a yard stick to reach in further. After that reading at a distance with the strobe without having to make contact was fairly easy. When used on slave pulleys you just need to know the ratio to do the math.
Good luck with whatever method you use

THANKS FOR THE TIP. NEVER THOUGHT OF USING A REFLECTIVE PAINT.
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Old 09-15-2016, 10:11 AM   #20
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"Easily" is a pliable word. Please explain or point me toward a net explanation link.


Thanks, Art
Sorry, the device I was using had no keypad.

There are several types of easily programmable microcontrollers for which an amazingly wide array of input and output devices are available. Perhaps the easiest is Arduino: https://www.arduino.cc/ It will take a little time (but if you like learning, it is enjoyable time), but you can easily learn to use the thing for about anything you can imagine. Basically trivial to hook up some sensors, calculate rpm, transmit data wirelessly and display on a small (or large) alpha (or graphic) mono (or color) display (or displays). Cost is surprisingly little.
There are plenty of on-line resources, but there is a beginers book by Blum that begins by teaching you to flash an LED (and includes Ohm's law, etc., so you understand how to wire it up) (ie, output), then to take input from a button to control the LED, and at that point, you are conceptually at least half way there.

ps -- at one point I made a device to measure my engine rpm and prop shaft rpm, adjust for the gear ratio and output the "slip" (on a prior boat, I burned both gears by not realizing that my oil pressure was slightly low, but low enough to cause the gears to slip). Since my slip was zero, I did not then build in an alarm, although that would have been "easy" to do.
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