How To Measure Diesel RPM

[flusher]

hey.. that's like an adult male toy store.

I know there is a good deal of junk there.. but on the other hand.. there truly are somegood deals especially for a tool you may only use once.. or for the hobbiest who needs a set of tools for tractor maintenance vs making a living off them.


soundguy

Yep, you have to be selective at HF.
I bought a $149 compound miter saw with laser at HF. Used it 5 years. Retired it when the plastic safety shield cracked up badly around the pivot screw. The motor and bearings (Chinese of course) were still going fine.
Also got 5 years out of a $89 pancake compressor at HF.
I'm not complaining.

 

[Soundguy]

Yep, you have to be selective at HF.
I bought a $149 compound miter saw with laser at HF. Used it 5 years. Retired it when the plastic safety shield cracked up badly around the pivot screw. The motor and bearings (Chinese of course) were still going fine.
Also got 5 years out of a $89 pancake compressor at HF.
I'm not complaining.

Funny you mention a pancake compressor from HF. i have one I got back in 97.. so it's now 13ys old. I actually used it and a 15 g spare air tank to paint my first 2 tractors.. so that poor thing ran continously.

I've changed the oil in it 3 times.

about 3ys ago.. it stopped pumping up past 20 psi. I was about to chuck it when i decided to open it up.. turns out the gasket betweent he head and cyl was bad.. melted and gummed up.. reeds were fine. Knowing i likely couldn't get oem parts for it, I simply grabbed some appropriate looking gasket paper fromt he sheld and an exacto knife and cutout what all looked like it needed cutting out on the 3 gaskets it needed.. one on either side of a spacer.. and one less critical looking one on a i/o manifold... to my surprise.. it worked. and in fact.. worked better than when new.. IE.. built air pressure faster.. methinks the oem gasket leaked a bit when new.

lil thing shows no signs of stopping.. I keep it inthe house garage for airing tires now.. with a newer better upright 30g/5hp unit out in the shop.

I paid 89$ as well for that compressor.. not bad for 6.80$ per year of use.. with the first 3 years being 'abuse'...

soundguy

 

[20 20]

Back to topic, if I'm not mistakin Northern tool also carrys some sort of tach's.

 

[JC-jetro]

Back to topic, if I'm not mistakin Northern tool also carrys some sort of tach's.

can't beat $20.99 and free shipping.

JC,

Digital Laser Photo Tachometer Non Contact RPM Tach : GadgetTown.com

 

[RobertN]

No doubt, very viable. Just pricey.

One thing I like about the current laser tach I use, is it is light, small. Our old strobe tachs were big ole honkers. I did like the fact e didn't have to monkey with reflective tape with the strobe-tach.

Used plenty of lockouts/tag-out. Mostly on 115VAC/20A or 230VAC 30A circuits. Mostly working on componenets of photoniic emission microscopes. Failure Analysis stuff for microprocessors and flash memory.

There is a ton of good information that is being dispersed here every day. I was just merely pointing out one option not talked about that is very viable.

For whom who have not heard of Lock out/Tag out.

 

[zzvyb6]

Follow up:

Got the HF Photo Tach. Put the batteries in, removed the display protector, applied 3/4" of tape to the crank pulley, started her up:

1100 rpm at idle (low should be 1450).

3280 rpm at fast idle (low, should be 3640).

The low idle made me suspicious of a bad engine mount or weak cylinder (she's a shaker). The low high-end made me believe the mower spindles were going a tad slow (not that 350 rpm is a huge change).

Interesting that both readings are low by about 350 rpm. I wonder if that drop is caused by wear/hours or a problem with the last dealer tuneup (flawed tach) or the HF tach is off. I'll check it against an AC motor just for reference.

This instrument came with an appropriate, protective case and a set of instructions in only one language so I didn't have to paw through sections for French, Islandic, Antarctic, or Bronx translations.

 

[JC-jetro]

Follow up:

Got the HF Photo Tach. Put the batteries in, removed the display protector, applied 3/4" of tape to the crank pulley, started her up:

1100 rpm at idle (low should be 1450).

3280 rpm at fast idle (low, should be 3640).

The low idle made me suspicious of a bad engine mount or weak cylinder (she's a shaker). The low high-end made me believe the mower spindles were going a tad slow (not that 350 rpm is a huge change).

Interesting that both readings are low by about 350 rpm. I wonder if that drop is caused by wear/hours or a problem with the last dealer tuneup (flawed tach) or the HF tach is off. I'll check it against an AC motor just for reference.

This instrument came with an appropriate, protective case and a set of instructions in only one language so I didn't have to paw through sections for French, Islandic, Antarctic, or Bronx translations.

350 rpm discrepancy/ inaccuracy for the range from 1000 to 2000 rpm is too much. Under 20-40 rpm one either low or high is tolerable. I'd suggest you to compare and contrast ( calibrate) with something that you know the rpm of. Your furnace motor rpm is most likely 1150 or on a single phase motor. The way motor leads are landed also make a difference on RPM. rpm information should be affixed inside your furnace sheet metal access door. Check your meter against that to see how off if any you are. if you have any other stuff around the hose such as a box fan can be used (direct drive) as long as the rated rpm is stamped on the device. Utility voltage fluctuation if any can make insignificant change in the reading.

JC<

did you measure your final pto shaft rpm?

 

[Soundguy]

could check against a vehicle with a tach as well.. like a car engine.. etc..

soundguy

 

[Treemonkey1000]

I have the same tester from Harbor as you do. I just haven't gotten it over to my tractor to try it out or bring it into work to see how accurate it is. You may aim the tach tester at a incandescent or flourescent lamp. Those are strobing at 60 hertz. Our eyes don't see it. Your tach tester might pick up the strobing. If not try a pair of polarized sunglasses in front of the tester lamp.. It might work.

 

[CFHartman]

something I would like to say about the strobe light. I worked on and rebuilt steam turbines. The strobe was very good when you had an idea were you were suppose to be but starting from scratch it was easy to find what they called a harmonica frequency. were it looked like everything was stopped. When sitting the trip on a turbine we also used a vibration tack. Once you brought the strobe in close to the vib tack you hat very good accuracy