Thread: Dial vernier calipers ?

I started off with vernier calipers, switched to dials, then electronic and now, finally, back to vernier type. I own a Tesa dial caliper (ebay) that has a bad rack...i get +/- 0.1 mm randomly, so it is used for welding layout now. My Mits is still good, but I find a high quality vernier type is smoother and dead accurate (to withinn the Abbe limits of accuracy for a caliper, at any rate)

One of the handiest devices I have is a pair of screw on points for a spare vernier...they allow precise transfer of hole spacing when doing a layout. My fabrication projects are a happier thing now

GQ

Plain vernier calipers are much tougher for general use, and can survive knocks that would break dial and electronic calipers. So I have them on the bench, and the more delicate ones stay in the cupboard.
I like metric/fractional inch verniers, but they aren't easy to find.

Jordan

Originally Posted by nadroj

Plain vernier calipers are much tougher for general use, and can survive knocks that would break dial and electronic calipers. So I have them on the bench, and the more delicate ones stay in the cupboard.
I like metric/fractional inch verniers, but they aren't easy to find.

Jordan

Thanks Jordan & everyone who have contributed to the Vernier discussion.
Talking with BT Bob last night, indicated he has experienced similiar problems.
I have a "Helios" brand made in Germany plain 6" sliding vernier, that has stood the test of time. Really, very little to go wrong with it.
Purchased new in 1960 or 52 yrs ago, & its still accurate. Lives in its felt lined wooden box, when not in use.
Like Bob I use a head magnifier a lot of the time, so may resort to using the trusted old sliding vernier, & the magnifier.
Trying to keep things simple, is not a bad way to go.
regards
Bruce

Bruce have a look at Mitutoyo "absolute" digital calipers I have 200 the mm coolant proof version which I use at work they are really nice to use.

Originally Posted by welder

Bruce have a look at Mitutoyo "absolute" digital calipers I have 200 the mm coolant proof version which I use at work they are really nice to use.

Andre
Thanks for that I will follow up.
By the way, how is the scraping job on you Shaper going ?
regards
Bruce
ps Ive been working on making up a special "Pin Micrometer" using the Mike head you gave me.
Photos will soon be shown.

When checking my mic I used to place a piece of cigarette paper between the jaws, close them gently, slide the paper out and close to your standard pressure. This cleans the surface of the jaws. These days I use the cloth at the opening of my cotton shirt. I never use the ratchet. After tens of thousands of measurements I can still after nearly 30yrs produce a more accurate pressure by hand (in my opinion). The ratchet always seemed to me to be to much like an impact tool.

The mic is a mitutoyo, about 30yrs old. I would like more of their equipment but as had been said they are now overpriced. If I remember correctly I bought the mic in about 1979-80 for $35 or so thru work at the time. Still a lot of money back then. I have an 8 inch no name digital vernier which I find excellent. Paid about $90 around 4yrs ago. The only problem is it does not turn itself off. It does not use much power but will go flat if forgotten for weeks at a time.

Dean

So you have a cloth attached to your cotton shirt or does someone attach it for you.

Originally Posted by pipeclay

So you have a cloth attached to your cotton shirt or does someone attach it for you.

I tried to attach cigarette paper at first but it would not stay there for long. Kept ripping off. Had to resort to cloth.

Dean

Originally Posted by cba_melbourne

I did not mean a ball. I meant the outer ring of a ball bearing. These are manufactured to a high degree of roundness. You take a 25mm (or 1" diameter) nominal outer diameter ball bearing. Both will fit between the anvils of your 25mm micrometer, so you can measure it. A 25mm ball bearing will measure very slightly larger than 25mm, because it is intended to be a press fit into a bore. Since your 25mm micrometer is calibrated with close jaws, you can make a correct absolute measurement. You will measure something like 25.003mm. Now take your 25-50mm micrometer and measure the same ball bearing, calibrate it to the same reading you had before, eg 25.003. Voila, calibrated without having had to buy a real standard.

Next micrometer one size up (75 - 100mm) can be done either using the method above, measuring a 75mm ball bearing that you read with the mike you just calibrated above. Or you could look up in a ball bearing tolerance table, how much bigger than 75mm is a standard ball bearing outer ring and use this value. In the former case, you have to accept a small inaccuracy due to your measurement errors adding up. In the latter case you have to accept the manufacturing tolerance of the ball bearing as your calibration inaccuracy (the tolerance of ball bearing diameters is in the order of 0.001 to 0.002mm, pretty much irrelevant if you only calibrate a standard resolution micrometer). Chris

Hi cba_melbourne,

Just a mo(supposed to be some smilies here) , metric bearings are toleranced from zero to the negative side of nominal on both ID and OD, except for some magneto bearings. The accepted tolerances published are greater than than you have indicated too, and they increase as the bearing size increases. Not trying to be a smart-****, just thought I'd mention it.
Hope you have a good festive season.

Cheers.

Originally Posted by Oldneweng

I tried to attach cigarette paper at first but it would not stay there for long. Kept ripping off. Had to resort to cloth.

Dean

Thats what I thought,all the best.

> metric bearings are toleranced from zero to the negative side of nominal on both ID and OD, except for some magneto bearings. The accepted tolerances published are greater than than you have indicated too, and they increase as the bearing size increases.

You are right on both counts. Tolerances are both negative. And a bearing of P0 precision class (a common automotive type bearing) with 25mm nominal outer diameter can be up to 9um smaller: from 25.000mm to 24.991mm.

Still, in a pinch and bare a proper calibration standard, a ball bearing is probably the most easy to find item suitable to roughly check the calibration of a basic micrometer of 0.01mm resolution. Its not perfect, but it can certainly tell if the micrometer is reading accurate to within one small line of the thimble scale.

For comparison, and to get a better feel for how long one micrometer is: a proper micrometer calibration standard that measures 25mm at 20C and is made of steel, would expand by more than 3um if warmed to 30C.

Just a fun brain exercise: if tomorrow we reach 40C in Melbourne, and the workshop has no aircon, it would not matter one iota if one was to use a ball bearing or a calibration standard.... both would be off by about the same amount...

I have a kingchrome digi vernier that has an error .05mm but I have a chinese vernier that is spot on well within .01mm anyhow. No dial or digi makes for more accurate measuring in my view. When I go for the final measurement I always check with a mic though most stuff I make is not that critical but I like to try and get it to size
Pete

To me, the main advantage of digital and dial calipers is speed. They are good if I need to do many measurements in one session. Vernier calipers are dependable but slow, which usually doesn't matter.

Jordan

Originally Posted by nadroj

To me, the main advantage of digital and dial calipers is speed. They are good if I need to do many measurements in one session. Vernier calipers are dependable but slow, which usually doesn't matter.

Jordan

Digital at least are easier to read without glasses which I have just started needing. I can still read without them but it is easier with them.

I thought I should point out that my comments about cleaning the jaws on my shirt fabric actually only relates to verniers (only 2). I realized that today when I cleaned my digital vernier. I still use paper for the mic. Usually printer paper these days as I have given up the habit many years ago.

Dean