Measuring Clearances

[Vintage Engine Repairs]

Chaps,

I did a thread on measuring cylinder walls. I wanted to follow up now that my Mitutoyo gauges and micrometers have arrived. It’s amazing how accurate telescoping gauges can be.
Thanks for everyone’s help and advice so far on this journey! My mistake, when I say “point 1 micron out” I actually meant to say “1 micron” etc

 

[heimannm]

I was going to complain about your usage of "micron" until I wrote it out. Indeed you are correct.



Mark

 

[rupedoggy]

So Tom it seems like you are thrilled to "discover" things that precision machinists have been doing for over a hundred years. Not that it isn't thrilling but really for chainsaws?

 

[Bob Hedgecutter]

So Tom it seems like you are thrilled to "discover" things that precision machinists have been doing for over a hundred years. Not that it isn't thrilling but really for chainsaws?

Lawnmower racing- coming to a city park near you!

 

[cuinrearview]

So Tom it seems like you are thrilled to "discover" things that precision machinists have been doing for over a hundred years. Not that it isn't thrilling but really for chainsaws?

You must have missed it Mike, he's moved on to large equipment now.

Is this your first time Rube Goldberging with Tom?

 

[Canyon Angler]

when I say “point 1 micron out” I actually meant to say “1 micron” etc

Tom, do you have any idea how infinitesimal a micron really is? For those of us who use English units, 1 micron = 0.000039"

That's less than one half of one ten-thousandth of an inch.

For comparison, a human HAIR ranges in diameter from about 50 microns to 100 microns.

Trust me on this, I promise you, you are not measuring anywhere even CLOSE to 1/50 or 1/100 the diameter of a human hair with a hand micrometer. You might think you are, but you ain't.

 

[Vintage Engine Repairs]

Tom, do you have any idea how infinitesimal a micron really is? For those of us who use English units, 1 micron = 0.000039"

That's less than one half of one ten-thousandth of an inch.

For comparison, a human HAIR ranges in diameter from about 50 microns to 100 microns.

Trust me on this, I promise you, you are not measuring anywhere even CLOSE to 1/50 or 1/100 the diameter of a human hair with a hand micrometer. You might think you are, but you ain't.

How am I getting the results I am then? The bearing is 20.000mm. The micrometer accurate to 2 micron and I’m getting anywhere between 19.997 to bang on 20.000mm. It’s not just luck..

Here is a guy who does exactly the same thing getting exactly the same result....

 

[Vintage Engine Repairs]

Worth mentioning, Mitutoyo also sell a hand micrometer to 0.1um or .1 micron.

 

[Canyon Angler]

Hmmmm....

Well, all I know is a micron is really, really, really, really, really, really, really freakin small. A sheet of Xerox paper that measures .004" (typical) is about 102 microns thick.

Maybe there's a machinist or engineer here who deals with these kinds of measurements who can weigh in...

 

[Canyon Angler]

Worth mentioning, Mitutoyo also sell a hand micrometer to 0.1um or .1 micron.

Cool, 0.1 micron is the diameter of a coronavirus particle. Not sure I'd want to try measuring the diameter of a COVID virus with a micrometer, but if ever I do, now I know where to get the tool.

I want a micrometer that I can measure the diameter of a quark with. Anybody who doesn't go to that level when rebuilding chainsaws should just stick to painting houses!

 

[Vintage Engine Repairs]

Cool, 0.1 micron is the diameter of a coronavirus particle. Not sure I'd want to try measuring the diameter of a COVID virus with a micrometer, but if ever I do, now I know where to get the tool.

I want a micrometer that I can measure the diameter of a quark with. Anybody who doesn't go to that level when rebuilding chainsaws should just stick to painting houses!

I’m using that as an example of when you said you can’t measure 1 micron with a hand micrometer, that you can, and you can go to .1 micron.

 

[lone wolf]

I’m using that as an example of when you said you can’t measure 1 micron with a hand micrometer, that you can, and you can go to .1 micron.

You boys is splittin hairs

 

[grizz55chev]

You boys is splittin hairs

It ain't the damn space shuttle! ( Teryldactal )

 

[lone wolf]

It ain't the damn space shuttle! ( Teryldactal )

Taryldactal yup! I know his work.

 

[Vintage Engine Repairs]

Gota love Taryl. His skits are fantastic.

 

[lone wolf]

It ain't the damn space shuttle! ( Teryldactal )

Thats what my Machinist used to say ,but watch out for a machinest when he says "you can see it from the Beach" or "if it dont fit get a bigger hammer" ask me how I know.

 

[lone wolf]

Gota love Taryl. His skits are fantastic.

Yup he's good.

 

[Canyon Angler]

I’m using that as an example of when you said you can’t measure 1 micron with a hand micrometer, that you can, and you can go to .1 micron.

Well, if you're measuring something to 0.1 micron, I guess the question becomes "Am I sure I don't have one coronavirus particle stuck onto my anvil, which would throw off my measured distance by 0.1 micron?"

Or maybe it's a single particle of aerosol cigarette smoke (0.1 micron diameter)...or jeez, a blonde CH (nearly a thousand x 0.1 micron)...you also need to consider the finish on the metal that you're measuring, and I suspect that when you magnify the surface to the point that you can see 0.1 micron, the surface of even the smoothest bearing imaginable looks like the Rocky Mountains...

Then we get into tolerances for the bore that the bearing fits into ... how many hundred thousand microns oversize is the bore that the bearing fits into? How many hundred thousand microns does the bearing expand and contract with each degree Celsius change in temperature?

It just starts to get silly after a while...much ado about (close to) nothing. For measuring bearings, I've never used anything more exotic than my dial caliper which is good to about half a mil. (I have a micrometer that reads to 0.0001" but that's overkill ... and a PITA to remember how to read the vernier.) For the rest, I rely on "gonna need a bigger hammer."

 

[Yukon Stihl]

You boys is splittin hairs

But which ones...
We all know that blonde curly hair is finer than black curly ones...
But Hey now we can get Tom to tell us exactly what the difference is

 

[Bob Hedgecutter]

But which ones...
We all know that blonde curly hair is finer than black curly ones...
But Hey now we can get Tom to tell us exactly what the difference is

Yes, but only after a library of PM's to those that have been measuring hair for the last 30 odd years, to ask if the hair measurement should be taken at the tip, the follicle, or mid distance of the length.