NEW PRODUCT Mitutoyo – Absolute Digimatic Digital Calipers. The most useful tool we’ve ever laid our hands on. These calipers are indestructible and ultra-precise. These digital calipers work by having a capacitive sensor instead of a rack and pinion, so they never go out of alignment even if, say, you accidentally drop them (a few times). One button converts the measurement from millimeters to inches. Perfect for measuring components. We’ve used the same pair multiple times daily for 5 years and never replaced the battery. They are very much treasured and we’re very pleased to be offer them in the store as The Best Calipers On Earth.
Large and clear LCD readout.
The ZERO/ABS key allows the display to be Zero-Set at any slider position along the scale for incremental comparison measurements.
The In./mm key instantly converts from Imperial to Metric (or vice versa)
Measuring Range Max:6″
Instrument Accuracy ±:0.001″
Lower Scale Measuring Range:0-6″/0-150 mm
Expected battery life: 3.5 years
Made in Japan
It took us a very long time to get in and at a great price, we think this is THE holiday gift this year for the maker, hacker, engineer or scientist in your life – or just get them for yourself, they’ll last a lifetime. Hard case included.
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I just peeled up the end of my brother’s (he used to do some machining) non-working pair(they already didn’t work) and it looks the same, not sure what brand these are, they good quality, no brand on it, only marking is "Stainless Hardened" on it, but it seems as most semi-high quality pairs use the same techinuque. I wonder how the chepo ones that are like $10 from harbor freight works?(i need to get a new pair, since thse don’t work, maybe i’ll pick up 2 of them and tear one apart)
Has anyone/will ladyada reverse engineer a pair of these? and like figure out how it actually measures and stuff
Ya, this pair was just cheep generic china brand, and with a little Google searching you can see that digital calipers use capacitance between the two PCBs
There’s a nice overview of capacitive sensors here:
The upshot is that the traces on the PCB are capacitively coupled to the plates on the bar (called the ‘stator’). Pump an oscillating signal into the plates on the PCB and you induce a signal in the stator.
By reading the signals across the stator plates, you can work out your position and the direction the slider is moving.