What do the expensive ones like mitutoyo do differently? I’ve got a pair and the are definetly more consistent than $30 neikos.
Cheap verniers are 'absolute modulo 10mm' as the T-shaped bar pattern repeats itself. They produce 'absolute' measurements by reading fast enough to keep track of how many whole bars they've moved.
Fancier verniers instead have two tracks in parallel, with slightly different pitches. Checking the offset between the two patterns at the current location gives an absolute measurement. This of course requires them to be factory calibrated etc.
They might also have slightly better electronics (some of these cheap verniers need a new battery every 3 months or so) or other differences.
At the same time, I soldered a tiny power switch into my cheap calipers to stop the battery drain issue.
https://www.amazon.com/Imperial-Stainless-Accurate-Shockproo...
I feel like the cash spent on replacing batteries in my 'crappy environment' calipers (usually harbor freight or equivalent brands) could've easily paid for keeping Mitutoyos in the bad environments, anyway.
It's one of those from-my-cold-dead-hands kinds of tools.
Fortunately that phase seems to have passed and it's now possible to buy very good digital calipers that consistently match my $300 Mitatoyos, stay off when turned off, and automatically turn off after a few minutes of inactivity.
I was so impressed I bought another two and gave them away, saves pulling out the Mitatoyos when someone at work wants to borrow 'em.
In your article you link to a patent on the cheaper T shaped coatings, do you also have a reference to a patent specifically using this system of parallel + different pitch tracks?
Great write up by the way!
From Wikipedia:
A vernier scale, named after Pierre Vernier, is a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation, thereby increasing resolution and reducing measurement uncertainty by using vernier acuity to reduce human estimation error.
This is because the cheap ones never power off, only turn off the lcd. They can’t power down without losing the position/calibration because they need to be aware when they move to a different section.
Gray codes[1]?
[1]: https://en.wikipedia.org/wiki/Gray_code#Position_encoders
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m...
that's true but a physical switch needs to be placed and soldered while the soft on/off just needs to be placed atop it on the traces on the pcb. cost just probably was the biggest issue.
I bought a €20 digital caliper (this one[1]) and the battery is still fine, 2½ years later.
That said, they absolutely do eat batteries faster than the expensive calipers.
"Turns out they pull almost as much current off (15uA) as they do on (17uA)."
https://www.reddit.com/r/harborfreight/comments/z7j8hp/fixed...