There are many kinds of calipers out there – vernier (like these), dial, digital, ones made of plastic, short ones, long ones, and calipers with specialty jaws or scales.
I use a digital caliper regularly, due to their ease of use and quick conversions, but there’s a special part in my heart – and workflow – for this Mitutoyo 6-inch/150mm vernier caliper (530-312).
This Mitutoyo caliper is made from stainless steel, and ones with carbide-tipped jaws are also available. I don’t use them in the presence of strong solvents or chemicals, but dirt, moisture, and grease are usually easily wiped away.
The moveable jaw can be locked in place using a thumbscrew, for when transferring measurements or making a workpiece. Another knurled knob allows for finer sliding adjustments.
It takes a little practice to be able to read a vernier scale, and for that last measurement you sometimes need good eyes and/or patience. But there’s a benefit to this – vernier calipers are less complex than dial or digital calipers, they never require batteries, there’s reasonably high precision, and you get that precision at a more affordable price point.
This caliper has 0.001 inch and 0.02mm graduations, and it is the “high accuracy” model, with 0.03mm accuracy.
You can make outside measurements with the large jaws. This is how I use the caliper much of the time. In this example, the measurement reads 0.215″, or 5.48mm.
There is a little bit of uncertainty in that last digit, but the resolution is high enough for quick and casual measurements. If you need higher precision, then you should consider using a micrometer instead, like the Mitutoyo digital micrometer I purchased last year and can heartily recommend.
Why wouldn’t you use micrometers all the time instead of calipers? Because with calipers, you can adjust the range from 0″ to 6″ – or whatever the maximum length of a particular model – in a split second. In order to provide very high resolution, micrometers have very small measurement ranges, and so spanning 0″ to 6″ would require 6 different – and pricey – tools.
You can also make inside measurements as well, with the shorter jaws. These jaws are very narrow, making them decent for measuring things like inside diameters.
You can also make depth adjustments, such as when you want to measure a flat-bottomed recess in a part. If you need to make this kind of measurement often, you should probably consider buying a depth gage. But calipers often do a good job for quick depth measurements.
Most calipers function in the same manner as this one, and only differ in how measurements are read.
There are many other vernier scale calipers in the 530-series, including models 530-104 and 530-316, which has fractional inch measurement markings and 1/128″ resolution. There are also calipers with metric-only markings.
I bought this one (model 530-312) because it had higher resolution in both inch and metric scales. It is currently priced at $80 to $85 on Amazon, which I believe is in the ballpark of what I spent years ago, and it’s made in Japan. It comes with a blue vinyl case that helps keep it clean when not in use.
Most of my precision measurement tools are Mitutoyo-branded, and I very highly recommend this brand.