How to read a vernier (caliper)

Looking at an early caliper, you'll notice that it kinda looks like a tomahawk and has a scale down it's length. More about the scale later. On the bottom left, the "blade of the hatchet" are the jaws of the caliper for measuring outside dimensions - think of a tube. This would measure the outside diameter. The "pike" on top of the hatchet is used for measuring inside dimensions . Again, think of a tube's inside diameter. Looking all the way to the right...I know it's hard to see...but there's a little "tail" sticking out of the center of the handle. That will measure the depth of a step or some other similar feature. That little button on the top near the "pike" is a locking screw. The one just below it is a thumb button.

Step 1 Holding the caliper

This is the proper way to hold a caliper. Use your thumb to slide the jaws open and closed. Yup, another tool that was totally designed for righties. Use the locking screw at the top if you want to set a dimension on the caliper and then check parts against your setting. Though it may not look it, the measurement between the inside and outside jaws are EXACTLY the same.

Comments

[Phil B]

Thank you for this. I think I will need to look at it a few more times. I looked at a vernier caliper and considered buying it a few months ago. I was having some trouble understanding it. Your explanation helps. Not much later I received some gift money and bought a digital caliper. It may be cheating, but it sure is easy.

[blackslax]

It's not cheating.
That's like saying it's cheating using a level instead of a clear plasstic tube and water.
There's no question about it - dial calipers and digital calipers are easier to use - especially for those of us that remember the Beatles.

Thanks!

[Phil B]

I do remember the Beatles, which means I also remember The Ed Sullivan Show.

[Eye Poker]

I bought a digital caliper and the thing never reads anywhere near a useful measurement, it's all in 1/128 and 1/64's I don't need to be anywhere near that accurate.

[Phil B]

My digital caliper reads in decimals, not fractions. I can convert to fractions on a slide rule or a calculator. My caliper also gives me the option of metric or English readings.

[amchaffie]

Fantastic explanation, I never really understood how to read off the smaller figures, Now hows about a metric one for us Brits :)

[blackslax]

I've never seen a metric vernier caliper - only dial calipers. Though I imagine that they do exist and that they would work relatively the same.

Thanks!

[Phil B]

I just found an on-line vernier caliper tutorial with a simulator you can adjust by dragging the jaw with your mouse. You can write your reading on a piece of paper and then click "show" to learn what the correct reading is to a tenth of a millimeter. I tried to link it through the rich text editor here, but it would not work, so here is the URL:

http://www.physics.smu.edu/~scalise/apparatus/caliper/tutorial/

[blackslax]

I would think that the Java is what is messing it up.


Thanks!

[Eye Poker]

I bought a cheap plastic caliper from Harbor freight and it gets more use than most tools in my shop.

[blackslax]

Yea, even a cheap plastic vernier caliper can give you some pretty good results. Just don't try to measure any freshly cut metals.

Thanks!

[rimar2000]

Very interesting instructive. It amazes me that almost nobody knows check read a vernier!

[blackslax]

Well, when you have dial calipers and digital calipers available, the vernier caliper gets overlooked. The best part about the vernier caliper is that it can last forever. I've seen dial calipers have their dial come off and of course - digitals need batteries. Not very sustainable.

Thanks!

[jdege]

It's nice to see some closeups that are actually in focus. It's all too rare, here.

[blackslax]

Thanks!

I had to go through 4 or 5 close-ups to get these.
They say a picture is worht a thousand words...but not blurry pictures.