"Harold and Susan Vordos" wrote in message
...

"JWho" wrote in message
news:Orlbf.547395$xm3.166892@attbi_s21...

"D Murphy" wrote in message
...
"JWho" wrote in
news:2Ehbf.547233$xm3.377596@attbi_s21:

I think I am going to look on eBay for a used name brand micrometer.
Is there some way to check to see if it is accurate? Do they come
with a metal bar that is .5" or 1" exactly or something like that??
I
thought I saw something in a set at Harbor Freight. Is a micrometer
adjustable to get it back to accurate? I'd hate to buy one off eBay
and it be inaccurate. Also, there are so many different models that
it is confusing. If I get one off eBay, it won't be a Chinese one.
I
can just go get a new one from Harbor Freight instead of eBay.

All micrometers are adjustable as far as I know. All of the brand name
ones are for certain. Most come with a "standard" which is a 1" long
rod
(for a 0-1" and a 1-2") that you can use to set zero. Often there is
no
standard with 0-1" micrometers, because you can just close the anvils
and
make sure it reads zero.

To truly check out a micrometer requires tools that few machinists
own.
You would need a set of gage blocks and an optical parallel along with
a
light source. Plus an indicator. You would check the readings against
the
gage blocks at 90 degree intervals throughout the travel of the
micrometer. You would then use the indicator to check the run out of
the
spindle at various points in the travel. Then you would use the
optical
parallel to check the flatness of the anvils and thier parallelism.

Trust me. If you buy a newer brand name micrometer off of Ebay you
really
won't need to do this. I've checked some vintage tools I collect just
for
the fun of it, and surprisingly 50-100 year old well used micrometers
rarely have a problem.

Individual gage blocks and micrometer standards are listed frequently
on
Ebay. If the micrometer of your dreams doesn't come with a standard,
you
can pick up an individual gage block or micrometer standard cheap and
easy. Once you get a mike, just let us know what it is and you'll get
help here on adjusting it.

I also read where you work in metric. You'll find good quality metric
micrometers are a little more scarce on Ebay than inch ones. But they
usually sell for cheap and are as a rule in very good shape.


--

Dan


Hi. Thanks for the informatio on the "standard". When I get to
shopping,
I
wil look for one that comes with a standard, just in case I may need it.

I will check my current 0" - 1" micrometer to see what it says with the
anvils touching.

Thank you. Thank you. Thank you.


Before closing the spindle on the anvil, place a sheet of paper between
them, then snug up the spindle so there's some drag on the paper, but not
so
much you can't move it. When you have the pressure just right, pull the
paper out. That cleans the spindle and anvil perfectly, unlike any other
method, and prevents tightening the two faces on something that can damage
them. Repeat the process until the paper comes out from between the mic
clean---

Harold



That sounds like a good method. I have been using a paper towel.

Thanks.