Basic question: vernier caliper

[triglyph]

I inherited a Fowler vernier caliper from my father. Where can I find info on how to use it. I know how to use a dial caliper, but not the older manual kind. It has both metric and inch scales.

The metric scale says 1/20th mm and the inch scale says 1/1000".

Thanks
Blain Brown
triglyph@aol.com

[Frank B. McClain]

You read that stile of caliper like you read a microcrometer. For more info check a machinests hand book. Hope this helps. Frank B. McClain

[Randy]

Do a Google search on "vernier caliper" and you'll get several helpful hits. The first is a cool little java applet you can play with. It depicts a .1mm resolution scale, but you'll get the general idea applicable to any vernier scale pretty quickly.

[halfnut]

Simple addition. You know how to read a micrometer? No nice numbers on barrel to read, you have to see which number lines up on vernier, sometimes you swear that more than one does, probably the reason someone came out with a dial caliper.

OK, you are reading decimals, first see how many inches. Then look and see how many hundredths, these lines are marked 1-9, then there should be 4 lines between these. They are each .025 , add this to total, now you have to see how far past this .025 mark it is. Now you look at the vernier, what number lines up, sure? Now add everything together.

This is a nice totally confusing explanation, find a book, or better yet find someone who knows how to read them, they can show you how much easier in person.

Metric scale reads similar, yours in 1/20s ,this is common, have seen metric in several different ways.

Good luck, verniers are usually very accurate, don't get chips in them.

[SGW]

Send to Starrett and ask for a copy of their catalog (it's free). It includes a page on "how to read a vernier caliper."

Halfnut's explanation is correct (except he means tenths, not hundredths, numbered 1-9),
but a picture helps.

I can expand a bit on his explanation, too, by trying to give an example. Suppose the 0 line on the vernier is positioned so it is between the 1" and 2" marks, between the smaller 6 and 7 marks, and somewhere between the 2nd and 3rd little tick marks that are between the 6 and 7 marks. At that point your know it's set at 1.65-something inches. Got that? Each of the little tick marks is .025", so you have 1.6" plus .050", plus something.
Now look at the 25 vernier lines. One of those will most closely line up with another line on the main scale. Suppose line 17 on the vernier scale conincides with a line on the main scale. So you have 1.65" + .017", or 1.667".
Now, that example assumes a 25-division vernier. They're also made with 50 divisions, and there are fractional ones graduated in 1/128ths, and no doubt other setups. Suveying transits have verniers in 15 minutes or 5 minutes or other amount of angle. But the general idea is the same for all of them.

[halfnut]

swg,

It's not what I say it is what I mean, whew, I try not to confuse anyone more than I am confused myself, but I do it anyway sometimes.

Have taught many people how to read verniers at work, much easier in person.

Here's one, digital calipers, I check out every set I can get my hands on with my 1.000 round Starrett standard. I have only found one out of six that said it was 1.0000 .

Every time someone in the plant gets a new set of calipers they bring them to tooling to get the depth rod ground down so it will fit .093 hole 50mm deep. Have ruined a bunch of calipers that way but that is what they want, so I do it.

These cheap vernier calipers, made in china, not even a brand name on some or them, check them with the standard and what do they say? 1.000 and 2.54mm on the button.

Why do people buy digital calipers? Status symbol? A lot of the engineers have them, guess they can't read a set of verniers.

I forgot about the Starrett catalog, should have remembered that.

[SGW]

Why a dial caliper instead of digital? Ease of reading, mostly, I expect. My 53-year-old eyes need a magnifying glass to read a vernier accurately. I've got only a vernier caliper though. It works.

I find it somewhat amazing that a technique for measuring thousandths of an inch dreamed up by Vernier in 1673 or whatever it was is still widely used over 300 years later.

[Ron LaDow]

Topic drift, but similar...
To establish drawing dimensions that don't align with the indexes on a scale, tilt the scale with respect to the line being measured. At some angle, the 1" or 10" mark will align with the 1" or 10" (or whatever you can find) dimension on the drawing. The scale and drawing dimensions can then be read as is a vernier.