Its been a while since I last made an Instructable, but finally working at the acclaimed Pier 9 with Autodesk, I felt it was due time I came back to sharing with the community I love so much.
So yee bought yourself a fancy new pair of calipers, and if you're anything like me, you're quite a snob about your precision tools and want the best of the best. Mitutoyo is a Japanese company that makes precision measurement tools, and as many of you reading this already know, these pair of calipers are no exception.
The Mitutoyo Absolute Digimatic Calipers are absolutely legendary among men (women, child, and elves alike), and they will probably outlive me, my children, and the impending apocalypse to come. But with so many China-made bootleg products flying around these days, one can't avoid the paranoia of, "How do i know these are the real deal?"
In this Instructable, I shall be sharing what I learned from an unnamed, unfaced, Canadian mystery man, and we be discussing the methods of verifying whether if your tool is cold-rolled japan steel folded 9000 times (which it isnt really), or if it was carved out of some rock in who-knows-where land.
Step 1: Ya Feelin It, Mr. Krabs?
First thing first! Does the tool feel legit? And no, I am not joking right now.
If you had yourself a SparkFun $10 generico calipero next to these bad bebes and ran the measuring face down the slide, you can immediately feel the difference. The Mitutoyo's feel like the entire thing was sliding on butter, and wouldn't make any of that nail-on-chalkboard sound as it slides along.
Also, check how much play there is between the parts. Lightly grab the sliding face, and shift it around. The real-deal of stainless steel should have little to no wobble, because whats the point of a precision instrument that wobbles....?
Step 2: Finish! or "Viimeistely" in Finnish
Now, I don't know a drop of the Finnish language, but I do know how to check for a good finish on a part. Let's check it out.
As a precision instrument, the metal on the calipers should be precision ground. That means that the surfaces are smooth as a baby's bottom and as even as the number 2. Also, the grinding job should be completely parallel to the length of the tool. Look at the surface of the metal very carefully, and you should notice faint grinding marks. Not 90 degrees, not 45, not even .0895. COMPLETELY PARALLEL to the tool.
I Googled the word "parallel", and it returned me my pics that I havent uploaded yet... the mind boggles.
As part of the finish, the Mitutoyos all come with ground down edges (except the sharp tip... cuz its a tip). With caution, run you fingers along the edges of the tools, and they should feel clean and ever so slightly rounded. They have been ground down for safety reasons, for tool life longevity, and also its just excellent machining practice.
These features should be all observable by sight and by touch. Also, if you see a whee bit nick in the metal, its MOST LIKELY FAKE. Self evidently, the Japanese take absolute pride in their work, and if it aint absolute quality, it's definite fatality.
Step 3: Electrique Properties
So I've been called a lot of things in my life, but never and electrician. With that note, let's proceed to analyze the electrical properties of a legit Mitutoyo caliper!
So if we remove the battery and hook up a power supply and a multimeter to the caliper's power terminal as seen in the picture (sorry if that doesnt help. Ask and I shall provide with a better image), we can see the current draw and voltage requirements of the caliper. Most calipers run off the same battery, and the Mitutoyo's come with a SR44 button cell, which supply 1.5V. Set yer power supply to that, and nothing more if you wanna see your calipers survive.
- When on, we can see the calipers draw somewhere around or under 5 micro-Amps. That's probably less then how much your average potato consumes! Talk about efficient.
From my tests with cheap generic-brand calipers, they consume around 17 micro-Amps, which is nearly 3 times as much, ergo 3 times shorter battery life.
- When off, the multimeter displays anywhere under 2 micro-Amps, depending on the batch. (Mine idles at .8, which is AMAZING).
DIGRESSION NOTE: You might wonder, "If it's off, shouldn't it be 0A?", and the answer is NAY! Since the calipers are absolute, it must keep track of its position while off as well, so it is aware of its distance from absolute 0 no matter what point you turn the caliper on from.
Tests on cheaper calipers have averaged to consume still around 15 micro-Amps while off. An ABSOFRICKINLUTELY RIDCULOUS +15X current draw from the Gundam-Space-Age Mitutoyos!
- BROWN OUT PROTECTION! So all the Mitutoyos come with a brown out protection built in, that warns you of low battery level, protects your product, and provides consistent performance. Since voltage across a battery drops as it is drained over usage, we can simulate it by dropping the power supply voltage to 1.4
The first thing you should notice is that your caliper displays the letter "B", which indicates a dying battery, and you should swap it out soon. If we further drop the voltage to 1.3V, we notice that the display simply cuts off. This is by design, to prevent your calipers from working with sub-optimal batteries.
Now what would a generic, not-protected, dinkem-doodah caliper do? If its a knock off, they typically dont have a battery indicator built in,so you'd never know. The first sign of failure would be the display on your caliper dimming out, making it hard to read the digits.
By further dropping the voltage, the display will continue to dim, but your measurement values will hit the ceiling fan and go absolutely everywhere. Without enough power, the caliper won't be able to accurately measure the capacitance across the slide (story for another time), and return incorrect/inconsistent values.
This can be actually harmful to your device in the long run as well, but a bad caliper might as well be a dead one.
Step 4: TLDR
Honestly, I should have started with this, but my ego desires you read everything.
FOR ALL THE PEOPLE LIKE ME WHO ARE TOO LAZY TO READ:
Indicators of a legitimate Mitutoyo caliper:
- Smooth operation of slider
- Minimal play/slop in measuring head
- Nice smooth surface finish
- Ground marks parallel to device length
- Ground down edges
- Low power consumption (long battery life)
- Low power battery indicator
- Brown-Out protection automatic shutoff.
I would like to thank Autodesk and Pier 9 for providing a fantastic lab space for me to conduct these test. And for yall, whether you read the whole thing or just the TLDR, thank you for reading and hope your measuring days are precise to .0001 inches! :)