Using a vernier

[crvc]

I watched U-tube videos on using a caliper. But most are in metric or measure in thousandths of an inch. I found an old caliper that shows 1/16th inch on the upper line and 1/32nd on the lower line. If I crack the jaws just barely so the zero notch is between true zero and the 1/32nd mark, the top scales meet at number three. So is the measurement 0.03/32?

http://i1325.photobucket.com/albums/u63 ... 0f99b4.jpg

kevin

[Ol'fogasaurus]

If the caliper's upper scale is in 1/8th (.125) of an inch, and the lower scale is in 1/32nds of an inch then the first mark on the lower scale 1/32 (.0323) from "0" and halfway between "0" and the first mark would be a 1/64 th of an inch (.0156). I think that is what you are after.

3/32 is .0938 from "0". Do you need that converted to mm? http://www.slotcar.com/drs/gachart.htm for example but there are better conversion tables out there.

[crvc]

Thanks, I think I'm getting it. It's like the year I started college and we were using slide rules. Then I dropped out and didn't go back for three years. When I went back suddenly everyone had TI-50s and slide rules were passé. Similarly, I think this manual Vernier needs to be replaced by a digital model.

kevin

[Ol'fogasaurus]

I seldom go to "garbage" sales but one of the few times I did go to one, on a lark I bought a fractional micrometer. It is next to useless on anything that needs to be close tolerance... or not in wood.

Where I worked we seldom worked with metric parts although it is probably more accurate as far as how it is broken down. We dealt with inches divided into decimals (100ths if an inch... or more. I co-designed a couple of parts as tight as 5 decimal places and have seen some 7 places and more. In design, you have to remember too that each decimal place gets exponentially more expensive ) rather than fractions. Some fasteners (for example), listed as standards, are still fractional so I found that converting them to decimals made it easier to deal with which is why I also gave you the decimal equivalent.

Lee

[Marc]

Stack up feeler gauges to various thicknesses and measure with the vernier calipers until you're confident that you can read it correctly.....

[helowrench]

Stack up feeler gauges to various thicknesses and measure with the vernier calipers until you're confident that you can read it correctly.....

in school fpr aviation, one instructor mentioned this for learning.
then he mentioned that, in a pinc on non critival items, this is also a method for verifying calibration

[Devastator]

I think you'd be amazed how few employees in a modern machine shop can still read vernier calipers. Even the dial calipers are becoming challenging since the "digital revolution". I still prefer the dial calipers over the digital version though. My batteries are never dead.

[crvc]

I stole this caliper from my dad's garage 15 years ago. He rebuilt dozens of bug engines using it to check for everything. I bet by now he's gotten a digital model.

kevin

[Ol'fogasaurus]

.... My batteries are never dead.

Wait until you get to be my age!!!!

I bought a set of cheap measuring tools like this (http://www.harborfreight.com/6-piece-te ... 94447.html) mainly for the divider and spring calipers until I could afford a better set. To be honest I yet have had to have a valid reason to use them but I still have them. The veneer caliper that came in the set (look at the price of them too as that is pretty cheap for the whole set) is very similar to what crvc has but it is a combination of inches on the top and metric on the bottom.

Even after all the years of doing what I did for a living, I had to stop and think about the markings for a second.

What Marc said and Devastator backed up is wise advice; get a known standard and check out the markings to see how true (accurate) they are. I also would be suspect of the accuracy of the whole unit unless I verified each mark mainly because of the type of markings (looks to be stamped/formed/rolled because of the raised and dimple marks) I see and the material and forming methods used. I am sure that the ambient temperature is going to affect the accuracy some and you probably don't know what the standard's accuracy temperature is... assuming you are going to rely on it for any great accuracy (talking about temperature is a little overkill on information but true).

[helowrench]

I ran across a caliper/micrometer set with those same dividers decades ago at Big Lots for $2 if memory serves. Bought them for the same reason, dividers alone. Then, on a whim, ran the 0-25mm vernier mic and vernier caliper through the calibration program at work. Amazingly enough, they both passed. Taught me a lesson in just how crudely made those things can be and still function to spec.

[Ol'fogasaurus]

Interesting. I haven't bothered to check mine out and probably won't. The caliper never did slide or work smoothly so it sits but I am happy to hear you had good luck with the "cheapies" you got. The depth gauge might be a thing to have after I do check it out. For some reason it is in two pieces right now.

Lee

[SCOTTRODS]

I have and use a HF Digital Caliper at work. It goes through the Calibration guys each year as well. It's pretty accurate to the 3rd digit... 'course for 8 bucks, I don't expect much anyway.

I prefer the Dial indicator type Calipers as well. Takes me a couple of seconds to re-adjust to them after going digital for a while though.

Nothing like a Digital Bore Micrometer Set though... Some expensive little buggers, but worth it on the Aviation stuff, I believe. Snap Gauges are OK. But the Digital Hole mics are the Shiznit.

[ALYKAT III]

I picked up a HF digital a few months back, as scar tissue on my eys is making it progressivly more difficult to read my old mic. Found that the same pieces measure at intervals of a few minutes will read up to three tens differently. Back to the old standard.

[crvc]

I ordered a composite digital caliper from Harbor. Once I got it I found it only measures to 0.01" or 0.1mm. It was only $8 but I wish I'd read the small print. For engines I believe measuring to 0.001" is the standard.

kevin

[Ol'fogasaurus]

Kevin, I also have one of those and it is OK for "approximating" to one or two decimal (for those of us in the US) like you said, .01. A machinist, for example may not use calipers for tight dimensions like .001(3 decimal places) or even tighter, they would probably be more prone to use mikes w/a standard. There are several machinists on STF so I should let them talk to this as it is part of their way of doing business. In my case: I just told them what I wanted but not necessarily how to do it (which is not 100% true as I would add a or many process specifications to a part design which could contain specific instructions on how to perform certain parts of the design).

(Some further discussions on the subject)

http://www.differencebetween.com/differ ... icrometer/

http://en.wikipedia.org/wiki/Caliper

http://vernier-caliper.com/

I hope this helps

Lee