It's Time

Yep it's time to get a digital vernier. Went to do some minor measurements on my project 8N and the measurement needed to be so many thousands. I thought no problem already have a vernier, which I haven't used in years, but it was the old type where you have to line up the lines, well couldn't see the lines anymore, then it hit, I'm old, had to get the magnifying glass out and a lot of light, must have been a sight to see, magnifying glass close, then far, finally got it where I wanted, and I'm near sighted usually good at seeing things close up, but not anymore, oh well it's time.

Welcome to the club!

es

Lines? You mean there are lines on there?

(quoted from post at 11:41:07 05/23/19) Yep it's time to get a digital vernier. Went to do some minor measurements on my project 8N and the measurement needed to be so many thousands. I thought no problem already have a vernier, which I haven't used in years, but it was the old type where you have to line up the lines, well couldn't see the lines anymore, then it hit, I'm old, had to get the magnifying glass out and a lot of light, must have been a sight to see, magnifying glass close, then far, finally got it where I wanted, and I'm near sighted usually good at seeing things close up, but not anymore, oh well it's time.

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Your instrument is a vernier caliper which means it uses a ruled slide to indicate values and has a secondary ruled scale (the vernier) for subdividing the major graduations on the slide to yield an additional decimal place of resolution. When you go shopping for a new instrument look for a "dial" or "digital" caliper. If you are having problems reading the vernier scale you will probably struggle with the dial and pointer on a dial caliper. Digital calipers are easy for old eyes to read and not overly expensive. I'd recommend you spend at least $50 and get something decent.

TOH

I'd recommend you spend at least $50 and get something decent.

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Ditto.

Inexpensive ones are readily available and work OK, but accuracy/precision/repeatability are worth a little extra.

When I worked at the hydro project, I compared digital calipers, and mics from Grizzly tool, to our Staretts. Identical readings
consistently. I wouldn't be too concerned about lack of accuracy. Don't know about HF.

(quoted from post at 20:42:18 05/23/19) When I worked at the hydro project, I compared digital calipers, and mics from Grizzly tool, to our Staretts. Identical readings
consistently. I wouldn't be too concerned about lack of accuracy. Don't know about HF.

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Digital micrometers and digital calipers are two different animals.

Micrometers are typically screw devices that rely on the pitch of the screw to translate turns of the barrel into linear displacement. A vernier on the barrel is used to subdivide a revolution of the barrel into smaller increments. The accuracy of the lead on the screw is the primary factor in the accuracy of the instrument. In the case of digital micrometers a microprocessor and rotary shaft encoder is used to count full and partial revolutions of the screw and display the corresoonding linear displacement on an LCD. This technology is robust and easy to manufacture and the inexpensive micrometers compare quite well with more expensive instruments.

Dial calipers work in a similar fashion using a precision ruled rack and a gear to spin a dial pointer. Again, with the exception of the really cheap plastic instruments, the accuracy of less expensive instruments compare quite favorably with more expensive instruments.

Which brings us to digital calipers. These instruments employ a vastly different measurement technology. They use a microprocessor and capacitive strips embedded in the beam to count incremental movements of the read head. The icroprocceser uses the counts to display the corresponding linear displacement. This technology is not as physically robust as the mainly mechanical technology used in micrometers and dial calipers. It is sensitive to missed counts caused by too rapid movement of the read head or contamination from dirt or liquids on the beam. In this realm the more expensive instruments clearly out class the really cheap ones. My $50 number was pretty arbitrary but if you want to get thousandths resolution with reasonable accuracy (+/- .001) avoid the really cheap instruments.

TOH