Inside a cheap set of eBay digital calipers
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- เผยแพร่เมื่อ 9 ธ.ค. 2020
- For such a lightweight plastic measuring device, the resolution of 0.1mm or 0.01" and repeatability is quite astonishing. Whilst not being suited to a professional machinist, these units are ideal for ordinary measurements, including designing 3D printed components.
It should be noted that the quiescent current of these devices is around 18uA, even when off (the display goes off until movement is detected).
Some users are reporting a very short battery life, but a typical 100mAh (0.1Ah) button cell should be able to supply 0.00002A for a very long time. (Theoretically 100's of days.)
The linear capacitive encoder in these units is very impressive. The physical encoder is seemingly very simple, with the bulk of the work being done by the ASIC (Application Specific Integrated Circuit). It's very similar in its cost optimisation to the cheap, but super-accurate weighing scales.
I'm really impressed by the accuracy of these units for their price. They are very common on eBay for as little as £5 (about $7 USD).
Here's a generic search link for the USA:-
www.ebay.com/sch/i.html?_from...
Or for those in the UK:-
www.ebay.co.uk/sch/i.html?_fr...
The standard search term is carbon fiber caliper.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.com/coffee.htm
This also keeps the channel independent of TH-cam's advertising algorithms allowing it to be a bit more dangerous and naughty. - วิทยาศาสตร์และเทคโนโลยี
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another completely pointless video for ad revenue
Sorry. This channel is aimed at technical people.
I found it interesting, if you do not then that is your decision.
Its not the video thats pointless, you just dont know shit, you brag about intelligence and knowledge in every of your comments, but you dont have both
Kind of weird mate
I mean he has a channel talking about tech products, what do you want him to upload lol... seems like someones jealous...
I suspect that most things in your life are pointless @Shawn/IO.
Have you thought of asking your parents why you were named after a Sheep 😂🤣😃
I deal with the lack of a hold function by just pressing zero, and closing it again. Then it shows the negative of what the measurement was.
Good idea.
I have that caliper as well and do the exact same, works great for me
Works pretty damn well aha
Good tip thanks👍
Oh God! I have just discovered I'm an idiot. Thank you for your help, Sylvia :)
Has a screwdriver with a changable tip. Has more than one to avoid changing the tip...
:BigClive logic
It's what people who actually use their tools do.
Well.. if you only need 2-3 bits for a job it does make sense that you don't want to constantly change the bits.
And it still lets you be versatile for many jobs where different combinations of those 2-3 bits are required for each one.
Also. If I recall correctly. The whole point of replaceable bits was to keep costs down in factories where robots and human workers could toil away using the same type of bit endlessly. Endlessly replacing that bit with a new cheap one as they wore out instead of a big new and comparatively expensive screwdriver each time.
So it does make sense in multiple ways to have multiple bit-holders. :)
@Nuke Dukem It was definitely a moment of recognition for me. :P
@@jmalmsten Id just glue the bit to the heads at that point. saves me a bunch of time that I use looking for a 3/8 driver or the 1/4 driver or the proprietary 1/8 driver.
I've often wondered how they made these things and managed to make them so cheaply yet with an incredible degree of accuracy. Thanks for making this interesting video.
this might be okay for home use, but for more applied uses, you might want to get something with a bit more resilience. i can't see that thing lasting too long for someone operating a lathe.
@@eatmywords yes totally agree. I've got a set that are better than the ones in the video but still cheap. It's only for DIY use but I wouldn't use something like that for serious and everyday use.
@@eatmywords Yeah, clearly, if you're doing lathe (or any kind of workshop tools) work, you won't be using 5 dollar calipers from Amazon. That would be like putting Walmart tires on a supercar. But while my calipers at home are a tiny bit better, going down to hundreds of a mm instead of just a tenth, it's still a pretty cheap one, and works perfectly well for anything to do with 3D printing (printers don't really get much accuracy beyond a tenth of a mm anyways), or any other random things I happen to come across and need to measure
I might have to eat my words and buy a better one soon tho, now that I've bought a cnc machine. But I don't really have any plans on using the cnc for anything super critically accurate anways.. for now
@@Excludos i've used 20€ catapilar for my years in CAD school (i'm not sure howto translate it to English but basically, i mesure sizing of part for a broken machine, and then i just create it with a fraiseuse Tourneuse) and it was actually quite good compared to my prof high end thingy, as long as you never drop it, it's fiiiiine
Would have been better if he'd looked up Vernier scale on Wikipedia. That's what's really going on at 12:28. Before electronics, it was purely a visual aid, and it's fascinating how it works. It's the reason I don't bother with the electronic ones. Yes it takes a little more mental effort, but it's a mental effort that I find quite enjoyable simply because it's so fascinating.
I worked for a company for a a number of months repairing precision measuring equipment including calipers, depth gauges, height gauges, micrometers, you name it. Mostly mechanical, but also electronic versions.
What you were able to surmise and figure out from what you saw, without knowing the sorts of things I was taught during training, is amazingly accurate.
The main problem with those digicals is once they go wonky, there is no currently available way to repair them.
With the analog ones you can always regrind, retension, rerack and realign, but the digital ones go in the recycle bin.
Interesting. Can you tell us more about how the Vernier gets read in these?
Mine was £7 summat from Aldi, so just chuck em if they go faulty
@@johnf3326 I ordered one two weeks ago from Aliexpress for 2,5€ free shipping XD
@@spicesmuggler2452 i got one from Aldi for 4,99€ and one from Aliexpress for 1,89€ with shipping.
@@johnf3326 it the 2 PCB'S that are the important bit, and there going to be made by a third party, PBCway springs to mind, but there more company that make PCB's and by the nature of the device, any take making that part, will have have high tolerances, and thing PCB's just have the stable don move shape much if at all unless being cooked, and the finished machine is self calibrating anyway knowing what it's own moray field pattern, as the two parts move?
would be intresting see fails where manufactured, to the number fully working ones, not including one build as lemons?
I looked into this technology a while back. Essentially what you have is a capacitive linear position sensor. It's not a vernier. The principal is that the teeth of the narrow comb on the sliding PCB are excited by the chip using sine waves. These teeth are in interleaved groups, and each group is fed a sine wave at a different phase. These teeth capacitively couple with the large comb on the measurement rule, which in turn capacitively couples back to the single long receiver bar back on the sliding PCB. The result is that the output from this bar is another sine wave, and critically the phase of this sine wave is determined by the position of the fine teeth relative to the large teeth. So a full 360˚ of phase corresponds with the pitch of the large teeth, 0.2 inch in this case. The chip measures this phase shift to determine the position relative to the set zero. So a 18˚ shift corresponds with 0.01 inch for example.
In fact in these cheap calipers it's all done digitally. The excitation is done using PWM coded sine waves, and in the example here they're fed in differential pairs, so that's 8 signals, four pairs, 45˚ apart. The output is then very spiky, but with a sine wave envelope which is recovered by digital filtering. Somebody scoped this version a few years ago - see web.archive.org/web/20120328090506if_/www.yadro.de/pics/hp-logic-analizer.jpg. You can see the four PWM sine wave differential pairs in the 8 digital traces at the bottom, and the single output signal before filtering at the top. Just imagine the peaks of the envelope of this signal are 0.1 inches apart and the signal shifting across with the slider and you've got the idea.
The reason for 56 small teeth rather than just 8 is to multiply capacitance and therefore multiply the signal output, plus averaging of any small physical inaccuracies in and impurities around the teeth. So each set of 8 small teeth in fact precisely line up with each pair of large teeth.
How does the absolute encoding feature work? How does A high-end Mitutoyo know its position immediately upon waking?
@@huntma3787 I have these same inexpensive calipers and they remember where they are when you turn it on too. Since it has a move to wake, as soon as you move it and since it has the last position stored it knows where it was / is. Now whether the Mitutoyo is really absolute or just does the same function, I don't know. I would tend to think it's the same as these. Now, if you took out the battery, moved it and then re-installed the battery and turned it on, that would tell you for sure if it is absolute or just storing it's last known position. But good question!
@@huntma3787 as long as they have a battery the cheap calipers never fully turn off....
all they do is turn of the display. so they are essentially always keeping track on where they are. other than that they are purely relative. though amazingly quick as demonstrated when they didnt miss a pulse during the rapid movement.
but that also means that they eat batteries like crazy.
After 10 years mine gave up and didn't switch on anymore. I purchased another one from ebay- a metal one. What arrived was trash. Astonishingly, I was able to transfer the display, pcb and housing to the old chassis. Everything was the same. I'm astonished the parts we're interchangeable. Thanks Clive for giving me the confidence to even attempt the fix rather than send both to the bin
It's pretty crazy how compatible many Chinese devices are, due to the absurd amount of corporate espionage and clones of older products.
@@albertweber1617 thats the meaning of efficiency;)
When these calipers came up we tested them with some small drops of water under the slider to see that they work with capacitive sensors. The instrument was in fact confused. After little drops had dried out it worked normal again.
Mine got wet and I had to wash it out and let it dry.
Was completely goofy until it dried, as good as ever once dry. I prefer the older ones from Harbor Freight (in the US), but the new ones are all plastic, sadly.
Tough too - I have dropped it a number of times.
I use the original visual Vernier scale only, as they existed before electronics. I never have to worry about liquids (except the kind that could etch the Vernier away ;)
@@TesserId you also need to worry tremendously about the mechanical characteristics of the metal the scale was printed on, whereas electronic ones (especially the advanced models from trusted brands) don't. Everything is a balancing act which depends solely on your use case.
"I wonder if this pops off". I've found that with (in)appropriate amounts of force and leverage anything will "pop off". The tricky part is getting it to pop back on again. : )
If brute force isn’t working, you aren’t using enough of it.
🤣
A tire storage place managed to hire someone who fit this perfectly
On his second day, the local newspapers told the story of how he had succesfully removed all 4 rims..... Without removing the lug bolts....
My version - "I wonder if this pops off" *snap* "Oh yes, just once!"
yes russian tank turrets pop of really well when an NLAW or JAVELIN is applied
When I saw Ave review one of these cheap calipers a couple of years ago, he almost made me feel ashamed of myself for owning one.
You've restored my self esteem and confidence. Thanks Clive. Keep your beard in a vise.
This cheap plastic one seems more accurate than my cheap steel ones from Harbor Freight. They never seem to go back to 0 reliably.
@@bigpjohnson Although this super simple design probably doesn't allow it, cheap designs resort to trickery. For example, my cheap bathroom scale remembers past measurements to give fake consistency. It's probably only accurate to five pounds, I mean I can literally grab a weight and it will claim I weigh the same, to the tenth of a pound.
@MichaelKingsfordGray what ?
It's worth keeping in mind that the flex in these calipers means that it's difficult to measure beyond .1mm without influencing the measurement just by the amount of pressure being put on the caliper.
More advanced calipers and micrometers have a wheel or knob with a clutch to close the jaws on the part being measured. The clutch is adjusted so the user can't apply more than a certain amount of force before it starts to slip. That way the pressure in the jaws is always the same, and the measurements are consistent. I have a $20 electronic caliper from Harbor Freight that has a wheel like that.
Agreed - repeatability and accuracy of finger pressure is pretty unreliable. I file small components to sub thou" accuracy so this particular instrument is not for me. For about three or four times the price, the stainless option is still great value and serves me well. They also have a variant that can be switched to display fractions of an inch - great for old fossils like me ;
@@bigoldgrizzly To be honest, if you need it down to the thou you'd just use a micrometer. There's a type for every sort of measurement.
@@233kosta quite so in most cases, These work well for me for small internal measurements, as well as external. Fitting steel reeds into slots with about half a thou clearance. Handy to be able to do both with the same instrument.
In case you are wondering, I make new reeds for concertinas. Just to make it more fiddly, some of these are also tapered both in thickness and width, along their length.
The ending bit where you moved it as fast as possible to prove it wasn't a relative measurement has convinced me to buy one of these. The plastic, even on good models, always felt like cheap junk to me and I was sure there's no way it's actually as accurate as it wants you to believe.
I'm sitting here, with my jaw hanging open, laughing at how accurate these things are even after taking it apart and jamming it back together. I bought a metal one a while back, for €7 at a store called Action (in NL). It has pretty much the exact same display, buttons and battery holder cap, but in silver/grey. I'm just amazed now I learned how they work, I always thought it would be like a little scroll wheel inside, but didn't expect it to work contactless. Amazing!
So the capacitive fingers do work exactly like a traditional vernier scale, with the wave of lined up fingers moving across then restarting at the beginning again.
Yeah, that's pretty much how it works.
That was my first thought, when I saw how the marks went in phase. Just like a vernier scale.
Yup, great for people who's eyes can't deal with Vernier scales any more.... Or so I'm told ;-)
Indeed. I always thought these things were wrong to call themselves 'vernier' calipers because they're not read via a Vernier scale like the typical non-electronic ones... but it turns out they do still use the Vernier scale principle behind the scenes. Nice!
Having taken apart for repair/cleaning more than a few mitatoyu
The reason for the slight offset of the tracking pads and the "piano" board is right there in the name of the device, "vernier caliper".
Glad this is in the comments. I have an entirely analog version of this! No electricity needed. Its a very smart way to make these super cheap.
Sadly, that's not why they put that in the listings. They just call any type of calipers "vernier calipers" because they either don't know what the words mean or are trying to spam keywords.
@@circadianrebel Maybe so, but Clive's disassembly had shown that the encoder is in fact a vernier scale 🤔
Was happy to see it being a vernier system after all too.
Yeah, I always had thought digital vernier was an oxymoron.
A digital analog. Or an analog of digital.
Explanation of how it can read so precisely while using so few contacts: being advertised as a Vernier caliper, it is most likely using an electronic version of a Vernier scale.
Vernier scales work by using a main scale for a larger unit, and then a smaller scale for a subdivision of that unit. the smaller scale is divided into lengths equal to the main unit minus the subdivision, so if youre between ticks on the main scale, each tick along will bring the ticks of the two scales more closely into alignment by precisely one subunit. this means you can find the scale's reading by counting along the smaller scale from the main unit you measured until you find the point at which the two scales align, and add the corresponding number of subunits.
It's easy to see how the circuitry displayed would be able to achieve this, and also explains the slight mismatch in length between the groups of contacts on the circuit board and the capacitive strips on the body.
That's what I thought as soon as the two scales were aligned. The circuit contacts are physically the same as mechanical Vernier callipers. I see no need for any complex 'waveform' or binary encoding of all of the elements. I don't have anywhere near the knowledge of electronics as 'BigClive', but it is basically a mechanical device with a digital output instead of a physical one.
I have watched other videos of his as I have the same scientific curiosity about almost anything.
When I saw it advertised as Vernier calipers I thought they were just misrepresenting the product. But when he opened it up and I saw the pattern, I assumed it was some kind of electronic version.
Remember though, just because something displays to more decimal places, doesn't mean it's accurate...
Indeed. Never confuse resolution with accuracy.
I've had metal digital calipers that had 0.01mm resolution, and the jaws to measure ID where off by about 0.5mm. Same for depth guage
even the expensive ones are inaccurate
Right you are! The number of decimal places relates to precision, not accuracy. An instrument may be precise but not accurate. Conversely, it may be accurate but not very precise.
It is repeatable. To obtain accurate measurements one has to have intimate knowledge of the condition of his own caliper jaws, correct pressure, fine motor skills and last but not least, regular cleaning.
"Carbon Fibre" or black plastic with random grit included, possibly soot (carbon) and grain dust (fibre).
To be fair, raw carbon fiber is DIRT cheap, really not an expensive material at all.
Probably glass filled nylon. Perhaps.
I've actually got one of these lol. I scratched it up a bit, it does have fiberglass in it. Still no idea what they marketed is having carbon fibre, these things cost like 10 USD...
Carbon black pigment if you want to be generous, it's not like marketing needs any grounding in reality!
There’s GFRP (glass fiber reinforced polymer), which is relatively commonly seen nowadays in high strength applications. There’s also CFRP, which is basically the same as GFRP except it swaps carbon fibers for the glass fibers.
It’s not the woven carbon fiber stuff people think of when they hear “carbon fiber”, but it’s still carbon fiber
Love how you checked those extra button positions for us. Again, BigClive goes above and beyond for his Patreons.
I was just typing a comment at the end of the video suggesting that he should have done so, and then realized that he was doing it as I was typing! lol
Why didn't he hook up a scope on the data channel? And analog output to get the sampling frequency!
I would imagine that, being that the wavelength of the sliding part is variable, that they are effectively self-calibrating, because moving them will emit a certain wavepattern at a certain place which the chip can then corrolate to a position along the length, even if you thrash it really fast as soon as it moves it knows exactly where it is. Also, reading if the waveform is lengthening or shortening will tell it what direction it's moving in with no other moving parts. Bloody genius.
I use digital calipers at work every day and I appreciate the amount of time I save compared to reading non electrical ones. Instant numbers showing up is such a time saver
6:18 - secret stylophone unlocked!
i can hear the metallica songs now
Stylophone? 🤔
Not kidding - As I read this I heard the Legend of Zelda "Hey you got some new shit" sound :D ... I dont even know why it was subcontious.
@@JesseCombsTwiZtedCheese th-cam.com/video/cF5JedknFGU/w-d-xo.html
Yup, Rolf Harris uses one to measure Kangaroo dicks
A buddy of mine used one of these to make an RDO for his drill press. The serial interface on these is the real secret gem. There are so many potential applications for it.
So those four pins are UART?
@@kaikart123 I came across a page with the hack and protocol, but since I had no interest in it, I didn't bookmark it.
That was over 10 years ago. So, I imagine they know even more by now.
@@piconano I got you, fam sites.google.com/site/marthalprojects/home/arduino/arduino-reads-digital-caliper
@@kaikart123 The pins just send a constant stream of bits, using the BCD protocol, widely used and hacked.
I have bought a few of these, only to find out the serial output does nothing on them. Not a peep, not even with added pullup resistors. So beware of that. The PCBs look exactly identical to these.
Keep up the good work mate, I absolutely LOVE your witty comments and the way you look at things. Awesome !
As a mechanical inspector on a UK military aircraft project, who uses Vernier callipers on a regular basis (not ones supplied by Lidl may I quickly add). This strip down has been so interesting and enlightening about an item of measuring equipment I've taken for granted for so long and often wondered how they actually do work. Thank you so much.
The clue is in the phrase "vernier scale" which is, according to Wikipedia, "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": "The vernier is a subsidiary scale replacing a single measured-value pointer, and has for instance ten divisions equal in distance to nine divisions on the main scale. The interpolated reading is obtained by observing which of the vernier scale graduations is co-incident with a graduation on the main scale, which is easier to perceive than visual estimation between two points."
en.wikipedia.org/wiki/Vernier_scale
I spent a lot of time reading verniers in my first year at university. I haven't done it since, but I remember the principles. I had never imagined an electronic vernier, but here one is, and what a good idea!
Yup. I have a small vernier ruler, with the pocket clip slider.
If you get a set I'd recommend storing them with the battery removed. And keep a spare battery with them. :-)
I've been there.
I got tired of replacing batteries every time they sit idle, so I just ponied up for a few pairs of Mitutoyo calipers...now I replace batteries after YEARS...not WEEKS.
Neat. My $10 set has a solar panel to charge the battery. I left it for a while in a box and indeed the battery had died. As soon as I went outside it turned on.
Could not agree more
I've some of these that are coming up to 3 years old and are still using the supplied battery. I've also got one that will eat the batteries quicker than pacman. Chinese lottery.
@@RK-kn1ud Mitutoyo Solar Digimatic, at least there are no counterfeits.
“So i’m going to remove the battery”
*firm whack*
“The battery is out”
This is the humor I came here for
That cracked me up too, both the whack and the announcement
Very interesting. I use mine all the time and was always amazed at how repeatable (and probably accurate) the measurements were. Thanks for explaining how it works!
... I never thought or be dared tacking mine apart I would brake it and could never put the thing back together ... but it's nice seeing what's in side 😂😝 ...
"Lets take it to bits." Would make a great T-shirt.
mug, tote bag, fridge magnet, computer sticker,
... band roadie jacket!!
"Let's take it to bits. One moment, please..."
'I shall pause'
The hammer of knowledge ;)
One moment please. For me :)
We would say it is "precise" because it has more digits. Accuracy has to do with the correct number being displayed.
That's right, more digits means you can be precisely wrong.
FWIW, I have a Mitutoyo calipers (about $175), plus several mechanical micrometers (one of them a Mitutoyo as well) and a digital mic that goes to half a tenth, plus about 4 Harbor Freight digital calipers. I've never found any inaccuracy between them. All four of the $20 HF calipers measure my inch standard at 1.000 inches, same as the mics and the Mitu. So I think the accuracy is there as well as the precision.
Yes. π=3 is accurate but not precise. π=7.47962974741 is very precise but not accurate.
Resolution is what he meant
He eventually does get to the point that it is both accurate and precise. Win!
Thkyou for putting it out. Very cleverly done.and accurate. Good to see the workings.
Impossible to stop watching, super work, thank You.
Thank you for this video. And it is indeed amazing to see how a cheap construction can still deliver an accurate measuring instrument.
This was like watching one of those nature documentaries where you see a baby bird being eyed up by lizards - you're so sure it's going to get eaten. There's no chance it could survive.... is there?
I love your knowledge and histories, and of course while see you tinker with electronics. I wish to have as many skill as you in this field someday. Thank you !
Thank you for this in-depth dive. For a project I'm building, I'm wanting a DRO and digital calipers will serve the purpose well enough. I want to take it a step further, however, in attempting to relocate the 3 axes LCDs / corresponding buttons to a single 3d printed encasement higher up on the machine and, after seeing this video, I'm confident that I can easily accommodate that, even to the extent of tying all 3 on / off functions into a single on / off function that controls all 3 simultaneously.
I might even be able to sort out a means to step-down volts / amps from the machine's main power to accommodate elimination of the batteries as well. I really appreciate your video.
2:26 You can use the back of the head to measure distances too. Works kinda like the depth gauge, but the larger flatter surface can be useful to keep your measurement square.
I was about to type the same thing. I saw Abom79 doing that years ago on his channel, and I use that feature all the time now for measuring offsets.
Lots of people miss this very handy fact.
Which part are you calling the back of the head?
@@JasperJanssen You can see what I mean @ 18:06
I always forget about this and end up using the depth gauge on the other end which can be a bit clumsy depending on what's being measured.
Just got myself a cheap digital calipers today. Same type. Perfect for my level of hobby and need so far.
Just a FYI, these “cheap” callipers don’t turn off completely. The encoder is constantly drawing power to remember its last position, allowing it to turn on when it’s moved.
Subsequently, the battery dies fairly quickly when the device is left with it in... I’ve started to store mine with the battery removed.
@@rushilkisoon Indeed, spent about twice as much to have a mechanical one (which turns out to be more accurate AND precise, bonus), because the empty batteries annoyed me fast.
I got a expensive metal type for more accurate measuring and this cheaper digital one for simple parts.
Quite weird but I got it for like 2 years now and the battery is still good 🤔 never take it out when I store it.
I bought one of these off of Amazon fairly recently and I thoroughly enjoy how great it is!
Exellent research you've done ! Thank you for such valuable informative tips 👍
"I'm going to remove the battery"
*CLONK*
"The battery is out."
I have one just like the amazon one, but not plastic caliper...used it very little but on second battery change it wouldn’t work unless I pushed hard with the batt cover off. Then I saw a small sliver of metal on the table. It is the middle piece that makes contact with the plus bottom of button battery. Tried to solder it back in, i possible, so I used copper braid (very thin) solder wick and soldered that in. Can’t put the cover back on but the battery sits so tight it’s no problem. At least got it working again. Very cheap battery contact point.
@@shader26 Ugh, I've got a Mitutoyo that's doing almost the same thing. The battery tray is junk across all brands.
I bought a cheap steel digital calipers years ago after buying my first 3D printer. It's since been probably my most used tool. I love em!
It's cool seeing how these take and record these measurements and it hurts my brain to think about the calculations required to interpret the signals coming from that capacitor array thing.
That skewed capacitor array works exactly like the vernier scale on traditional calipers. Detecting which line matches up gives the least significant digit, while counting the large marks passed gives the first digits. Write the two halves after each other, then apply the inch/mm unit conversion. Of cause, having 8 measuring channels suggests the use of binary digits instead of decimal ones.
I am impressed that you were able to dis- and reassemble this without once (except when quoting the eBay title) uttering the word "vernier"!
I was so curious all these days how these things work, thanks for explaing and showing them
"Let's grab a random nozzle" - that's one of my favourite party games.
Fascinating, one of your very, very best!
i just love your channel... BRILLIANT way to see how things work :)
Excellent video Clive, very much worth the time watching.
It is uncanny seeing the exact same calipers I bought a while ago being torn down by The Big Clive.
Same here. Guess all the companies are buying from the same factory
Exact same here haha
Got mine from ebay for measuring 3d prints, though it only reads up to 155.3mm instead of 156.3mmm :-)
What if they are your calipers? You never know when some random TH-camr may pay a visit to your home during your sleep.
@@peterrockell1527 so who nicked the other milimeter?
I've got the exact same calipers. Had it for years, has always worked really well
I have the exact same caliper and am very impressed with it, after pressing zero and then pulling all the way back and also reading 1563mm. I use it mainly for my electric bike conversion project while also adding mudguards and other accessories that need them to accurately measure fiddly nuts and bolts washers without the guesswork and are easier to read than the manual steel version which is difficult to read after time and tarnish.
Thank glad you did the extra bit trying the buttons at the end... My head couldn't cope with the video ending and not finding that out!!!
Just thought you would like this random bit of info, these are used to measure the thickness of the biscuits made at a factory I did a job at recently.
I guess that makes sense for uniform packaging and weight.
:) I find the use of a pair of precision calipers to measure cookies hilarious, but it's even funnier in America, our biscuits being big soft, squishy fluffy irregularly shaped flaky things.
@@tedhaubrich This particular biscuit company had imported a machine from italy to make the biscuit dough to relieve the poor lad who hand made it every day. The machine was a giant and cost £100,000 or so. It couldn't make a flat piece of biscuit dough. I told them it wasn't a surprise as it was a machine designed for making pasta.
We measure the thickness of biscuits with our teeth.
I love biscuits and I love precision.... Precision biscuits?....Wow, mind blown 🤯
I've been using one of the slightly-better-but-cheap ones that go to hundredths of a millimeter. Always wondered how they work, thanks for taking the time to take those apart! I've found that hundredths of a millimeter are really useful (almost mandatory) in 3d printing since filament widths can vary by brand, anywhere from 1.6 to 1.8 mm. being able to tell 1.72 mm filament from 1.78 will often make or break a print since the volume of plastic being extruded is dependent on filament width. Also getting that first layer to come in at exactly .15 mm (or whatever you're printing at) is also really important.
I watched this video over a year ago but came back after measuring a soapy part of my shower. The read measurements went haywire: 0 was 0 but 20mm was 80 something and then 30 was 40 etc. it just bounced around! I thought of this video and realized the contacts must be contaminated. A quick tear-down and wipe with an alcohol pad and then re-re-watching this vid very close to understand where the pieces went - thanks Clive you saved me a few days without a micrometer and $9!!
Have the same and works great. This technique could be used for digital (and motorized) potentiometers for audio mixers. The zero function can be used to set a memory location to be able to move to exactly to the same position. When motorized, it can be used to fade-in to exactly the same position. Very clever design, love it. Thank you for showing us.
Thanks for this one Clive. It was very informative.
Re the very last bit: it’s actually not just tracking it at jphigh speed - the capacitive vernier system provides an absolute position, rather than relative. Or at least, it’s absolute within the repetition horizon, which is probably something like 30 cm. If they get super long, you might be able to get a situation where it’s off by , but never by a small amount.
Im pretty sure you're wrong there.
That's a simple capacitive interference sensor with a repeating pattern. It's definitely a relative position sensor and needs to be set to zero by the user at some position.
The reason it doesn't lose track of position is because the sample rate is faster than the speed you can move it, quite trivial these days with very high speed MCUs and the pattern repeat being large, about 20mm long.
(Edit) sorry it's 20mm long for half a phase so maybe 40mm long for a full phase.
@@wizrom3046 sounds like we need a follow up video.
I am in Electronics hobbyst and I have been using one of these since 2008, it is doing its job just fine which is satisfactory for me.
That was a VERY interesting video! Thanks! I'll certainly be looking at getting a set of these now!
now only if there was a way to feed that data of a control board for feedback of CNC as most low end board does not have leaner encoder feedback but if it was there then all low end CNC (small PCB mill , 3D printer , Engreaver & Laser cutter )would become super accurate
th-cam.com/video/8TAvbxLuBEU/w-d-xo.html
I am not an expert but I think the challenge with PCB mills and 3D printers is frame rigidity more so than inaccurate stepper motors.
@@sourcefollower It doesn't matter how rigid the frame is if the X,Y and Z axis screws aren't accurate enough in their pitch to produce a resolution of at least .02 mm.
There are many other factors that apply more than a rigid frame, like squareness of the axes and backlash in the screws.
@@gangleweed If the CNC machine was using scales along each axis to position itself, it wouldn't need to rely on counting turns on a lead screw. Move 6mm, would be move X position on scale - not turn (6mm/thread pitch) rotations.
@@52Ford It's always been done with an accurate ball screw....why change what has always been reliable and simple.
I would love to see the differences in the 0.1mm precision calipers and the 0.01mm precision version. I'm curious if it's just more lines on the respective pieces or if it's done inside the processor itself.
I'd assume it's both. Like considering the actual sizes involved on two paralel surfaces i'd say they use differwnt tech process to make pcb more accurate, like using different photoresist(the better the "resolution" at which it can "harden" the costier it gets), different mask tech(i don't even know what they do it with in high end machinery, maybe some fancy pants uv projectors with complicated optical system), better, more accurate enclosures, etc
As user of the old visual Verniers (never bothered with electronic ones), it's pretty obvious that it would either have to be an order of magnitude smaller or an order of magnitude more lines. If it were to turn out that they were the same (which they might well be), is one rounding for a cheap display, or is the other algorithmically advantaged? With a computer science degree, I'm trying to imagine what that would entail.
Ah right! Was wondering why anyone would reinvent the 'wheel' (processor) when they have existed off the shelf for 20 years and are likely now dirt cheap .. makes sense that the cost would have been cut in the encoder resolution/accuracy, and so overall assembly.
@@JimTheZombieHunter We've pulled apart both 0.1 mm increment plastic (carbon fiber) units and 0.01 mm increment metal units. They appear virtually the same inside. The difference is in the display, in that the plastic unit doesn't have the extra digit. Presumably because the plastic one would not have the repeatability of the metal caliper. Maybe they are more precise in manufacturing the pads of the unit with higher resolution.
@@TesserId I _don't think_ that would actually be necessary. Additional precision and/or more lines of some sort may be required (though maybe not; they may just not display the extra digit on these, but be capable of calculating it), but even if so... well, I'm not sure, but I suspect there could be tricks done by having just different offsets on some of the things.
Thank you very much for this. It helps me put mine together. Still works perfectly, surprisingly.
after having this a while i found the unit kept reseting the value like zero was being push. thanks for taking it apart so i knew what to expect. cleaning all contacts with nail varnish remover and working great again now!
Thanks to the data port (which is a premium feature in 'real' micrometers), one could build a super cheap super high accuracy linear actuator servo!
The mechanical bits are important too. Straightness, parallelism, rigidity, stiffness, etc. They also have an impact depending on what is being measured. Having a locking screw and being able to use the sharp metal tips of the interior width gauge to transfer point to point measurements can be really useful. Thanks for the video!
Definitely worth the extra fiver to get a metal set in lidl or wherever
Have been using these for 25 years and being an electro geek, always wondered how they worked so cheers
This is what it's all about. Brilliant, elegant design with that element of surprise and very clever detail. Put this one on the Greatest Hits reel.
I calibrate these as part of my job. The spring bit that fell out we call gibs and on the steel version we have, there is 2 small screws on the top which can be adjusted to stop the jaws flexing.
We call them quadri-verniers bottom points for measuring external, top points for internal, thin rod for small hole depths and the fourth measuring face is at the other end which can be used for measuring steps, so the end of the Vernier to the end that slides along the back. These should be ground square to each other.
Biggest problem I find is oily residue on the face of the vernier which get in the inside of the vernier requiring stripping down and cleaning.
We would never use the plastic tenth version, not accurate enough for us and even these are called verniers as the size will need very near the actual size you are measuring ;) we use micrometres, internal micrometres, depth micrometres, to ensure accuracy for small hole you get 3 legged internal micrometres accurate to about .0002"
The tightest tolerance we get on things is about +/- .001" but can be just one direction.
I generally calibrate to +/-.0005" for micrometres but for thread gauges it would be .0001" accuracy I'm looking for.
Working in oil sector I'm stuck in Imperial sizes, but we do metric but convert sizes across from Imperial
Can you explain the fourth face thing for measuring steps, please? I'm familiar with the other three; internal, external and depth, but not steps
@@DrGreenGiant if you were to look at the end opposite the end the small rod comes out of and slide the jaws apart you will see 2 faces which are about 1 inch long as these are wider than the end the rod comes out of they are more stable at measuring steps than the short end. So your using the opposite end from the rod. It's hard to describe but hopefully you get the idea.
@@tazz1669 I was able to visualize your description, but i have used this type of tool before.
8:24 : The mystery button next to the inch/mm one used to allow you (in the inch mode) to switch between decimal and fractional values e.g. 1.500 → 1½
the missing button on the OFF/ON and ZERO buttons row used to be HOLD.
Thanks a million for this video. I'd taken mine out of a drawer for an upcoming customer visit next week, and left the calipers on my desk. My seven year old picked them up this evening, waving them around like a sword stabbing things in my office and somehow broke them into pieces. I watched your video and was able to reassemble them in a few minutes. They still work great and now my sword is fully functional again. Thank you!
Best thorough evaluation, and especially glad you tested the mystery buttons to satisfy our curiosity. Would like to see experiments with the data connector..
What I was told during my apprenticeship at a machining shop was that calipers are only accurate to 0.1 mm for measuring, but you can use the added digit (on professional calipers) to see about where you are with regards to the measurement. What it means is that if you had to measure something to 10.5 mm +- 0.02 mm you could not use the calipers to do that, you'd have to use the micrometers.
The true accuracy and precision of a caliper should be stated in the user manual.
The way I understand these encoders is this: "They work like a vernier, so...black magic and you've got a precise measure"
This might put it into perspective. Look for the image that the description begins with :Rotary encoder for angle-measuring devices marked in 3-bit binary".
en.wikipedia.org/wiki/Rotary_encoder
It's a fairly old concept, as in going back farther than me by quite a bit and I'm a fair bit older than dirt.
But, a mechanical version can be easily found in an old wind up music box. Or, in concept, Big Ben, save it used a rather fascinating cog work encoding (the maintenance team happily answers questions by e-mail).
@@spvillano Still black magic.
Like a multimeter switch
@@NicksStuff heh, I've had to fix my own multimeter back in the day. Just another wafer switch based encoder.
Aka, royal pain in the balls...
Like the vernier scale on an old mechanical version.
@@SilverWrinkly Yeah, black magic as well. I understand it perfectly every time someone explains it to me...but that lasts 5 minutes
Thanks Clive! You saved me after I carelessly took apart my 12" (300mm) digital calipers and didn't note where all the pieces came from as they just fell out after I took out the screws in the wrong order. Although mine were a bit different, I was able to learn enough to reassemble (after repairing a solder joint on the + contact) and it's now working again! :-)
Interference patterns are so useful. Linear scales and linear laser measurement systems use optical interference. And I've used Sony Magnascales that have two magnetic tracks along the length of the scale, 90degrees out of phase; the resulting out-of-phase magnetic fields were interpreted by simple electronics to determine position.
Always a good day when you post a video. Keep up the great work, sir!
BlondiHacks says always wipe the jaws clean before zeroing out.
Also use your thumb to apply a little pressure as you zero it, try and maintain the same level of pressure when taking measurements.
@@Nate3094
I like to just gently nudge it up and then let it go. If I need to be sure of the exact size, I take 3 or more readings and rezero each time.
at my job i used them all the time. mine had a little wheel as a thumb rest and you could turn the wheel with your thumb to slide the bar precisely. i personally hate the model that dont have the little wheel. its way harder to use them.
@@2000jago try opening the jaws without the wheel, you have to put your thumb way forward and try to grab the unit to drag it open. with the wheel thing, you just wind it up backyard and the module scoot backward.
I always wipe the jaws with my bare fingers and feel for foreign matter, before pinching the jaws with thumb and middle finger, while resetting the zero, with my index finger.
It's second nature now!
13:00 Hi Clive. This pattern is the grey code pattern for encoding. This is a grey code linear encoder pattern. Grey code being important as it is an absolute method of measuring position regardless of power loss. :-)
Agreed
No, it's actually a 7:8 Vernier scale. Human readable Vernier scales are 9:10 ratio, but for obvious binary reasons this scale is based on a power of 2.
I almost laughed when I saw Vernier on the listing but I'm impressed that it is actually used.
Grey scale is different in that only one bit changes as the number increases or decreases. That's not the case here.
@@chrishartley1210 Vernier scale is not absolute. Grey code is.
@@StreuB1 it's an absolute linear encoder, that's why no mater how fast he moved it, the reading was picked up.
@@StreuB1 I agree, but that is still a Vernier scale.
Grey code goes (in binary) 0,1,3 2,6,7,5,4,12,13,15,14,10,11,9,8... Please tell me where you see that pattern.
I worked with grey code 40 years ago (and since), it's not something you forget in a hurry.
Thanks for the interesting video. I've used my digital calipers purchased off ebay, 10 years ago, nigh on every day. Apart from a few battery changes, still works and looks as good as the day it arrived. For the price absolutely amazing value. Even more so as my eyesight isn't as good as it used to be. Easy to read.
So I have a somewhat more expensive steel version of this that goes down to hundredths of millimetres, but the black plastic bit with the screen is absolutely identical to this one! I was always really surprised about how accurate is seemed to be, glad I know how it works now.
Bought one almost identical 2 years ago as to test out. It's still works and hasn't failed me.
Harbor Freight? $9.99 today :)
Nice review and teardown, aaaand bonus footage 😀 Thanks Clive !
Loved the video! Gave me the confidence to take my broken pair apart and clean the inside and bring them back to life!
This is great, I've always wondered how these work.
Yeah saves me from tearing mine apart
I have the exact same calipers and they're totally adequate for my needs. However here's two tips;
1) Remove the battery when it's stored, otherwise it may go flat. This may be due to carrying them in my car. The jolts may be switching it on too many times.
2) If it starts to read just half of the true measurement, just remove and replace the battery. Reboot!
Thanks Clive, that was very informative.
The batteries just go flat because there is no true power switch so there is always a small parasitic loss as the circuitry inside constantly monitors for the pressing of a switch. It's the same with all sorts of devices, like remote controls which do, of course, have much more batery capacity. I too remove the button batteries from these type of devices when I put them away.
Thank you for number 2.
Thanks, Clive, I've disassembled a couple old calipers, metal and I believe one carbon fiber, as they've ended their lives, and been replaced. I came to similar conclusions without as much solid data, but appreciate your filling in the uncertain blanks. I too, find them incredibly accurate and repeatable, given their price, about 12 dollars for stainless, and five or so for the carbon fiber here in the US. Thanks again, always interesting what you find!
I am at work now and watching your videos 😁 absolutely love your channel 👍
Incredible how it stays on track even after racking it furiously. this used to be only possible with the expensive ones. Shows that even that tech is simple and cheap to manufacture
could just be the trade-off for lost precision.
the thing is when they start to have trouble its permanent. i used one that never kept its zero. i had to constantly try to clean it and zero it out each day.
𓂸... What?
@@operator8014 , well if you have a tenth of numbers to keep track of, you may be able to do it ten times faster, right?
So it could be that both fast tracking AND double digit precision is still only possible with expensive calipers.
Bloody hell. I never imagined these would be so interesting to learn how they work. Amazing technology huh!
thank you for explaining how it works i took mine apart and couldn't figure out where the metal piece goes but thanks to you i was able to get it back together 😅
These cheap plastic verniers are brilliant!... I bought several of them to leave dotted in strategic places around my workplace... Plenty accurate enough for a quick measurement 👍
There is a fourth measurement you can take with calipers like that that most people don't realize. Aside from the tail, you can also use the opposite end. Since the two parts are flush at the "Left" end, you can measure a step.
If you see and work out how a metal manual vernier works ...im sure you will see how the electronics and circuits look similar
This video actualy helps me in making something I am working on. Thank you very much.
I've used this exact mode for 3 years in the workshop. Gone through 2 batteries. still going strong (and accurately)
Best tool ever. I have the 8"/200mm version and it measures down to 0.01mm/0.001". Sometimes I just wander round the house measuring random items because I can.
I keep an extra set next to my chair where I watch tv. It’s amazing how often I am fiddling with some gadget or idea and end up using them. I have one in the basement workshop, one in the upstairs craft room, and one in the family/tv room.
hahahaha, same here!
Nice work Clive . It uses interdigital capacitors & a vernier effect . The unused buttons are almost certain to be associated with the SPC ( Statistical Process Control ) port ( Data port ) , used by some manufacturers to monitor production . Keep up the good work !
Some can have a fraction/ inch display.
Besides SPC there are a number of data communication protocols used in calipers. Cables and boxes are available for expensive calipers to connect to a computer but the cheap ones don’t even tell you they are there. They are hidden under unlabeled covers.
neat to see the vernier is still in there. surprised Clive did not recognize it.
Amazing optimized design
I genuinely was looking for a video to take exactly this caliper apart because I have the same one and was wondering how they work. Great video!