Off topic.. Reading a micrometer

[StarTech]

Well that stinks. I couldn't even find a manual for it online either.

 

[Rivets]

I taught my students to read a mic this way.
1. Numbers running left to right are dollars.
2. Lines between the numbers are quarters.
3. Lines going around the thimble are pennies.
4. Lines on the barrel (1-10) are tenths of a penny.

The reading in you original post is this.
9 dollars. $9.00
3 quarters. .75
5 pennies. .05
6 tenths. .006

Add it up. $9.806
Move decimal point one step left for final measurement. .9806”
Sixth grade students caught on to this method in one class period.

 

[sgkent]

I see $9.0 + .75 + .24 + .004 or .006 ($9.994 or $9.996) depending on the photo. A full revolution is .025" and it is almost that. 4 turns on that one is .1" If one wants to work it backwards, unscrewing it .0004 would make it 1.000" which is barely showing as the 4th hack mark. 1.000" minus .0004 would be .9996". Another way is that is about 1/2 a hatch mark on the barrel from a full1.000" inch. If it was screwed in to the first hatch mark it would be .001" less than 1.000" or .999". Since it is about 1/2 a hatch mark it is about .9995". The fine division is a 4 or a 6 depending on the actual angle the viewer looks at. The photos are not all that good which does not help.

 

[Rivets]

sgkent, you may be correct, but as you said the picture is not very good. If it were as you said we should be able to see a line between 20-0, which would indicate 20-25. I don’t see that, which is why I taught my students read what you see, not what you think it should be. More than likely this is a cheap mic, out of calibration, which is why we disagree.

 

[sgkent]

if my memory serves me, and it may not because I don't use one but a couple times a year these days, 25 and 0 are the same hash. one turn would be 0 to 5, 5+ to 10, 10+ to15, 15+ to 20, and 20+ back to 0 which serves as 25 because the hash marks on the stem reveal every 25. It is really irrelevant. The OP should be not asking someone on the Internet to read his mic. When a master machinist taught me the first thing he did was scold me politely for not putting the mic back in the box when not in use, and leaving it in the sun, and the next thing he did was show me how to hold it so the heat of my hand would not alter the readings. He build Formula One engines, Indy engines and Al Unser Jr was one of his clients - so I tend to trust what Bill taught me when he said, don't lay it in the sun or it will warm up. Whatever you do don't drop it.

 

[Scrubcadet10]

Fancy C clamp

 

[Hammermechanicman]

Old school Lufkin. Was my father's and i think he got when he worked for the CCC during the depression. Still accurate.

 

[Rivets]

Believe it or not I laid In bed last night and this thread kept running through my mind. Am I making a mistake? YES. Being that this is a vernier micrometer made me not believe my own eyes. Sgkent is correct, I am wrong, another learning experience, not a mistake. Sorry to the OP for leading you in the wrong direction.

 

[Gord Baker]

1.05"

 

[CaptFerd]

good example