How Does A Digital Caliper Work?

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How Does A Digital Caliper Work?
Today we look at what makes a digital caliper work. It was time for me to upgrade to new calipers as the old ones were getting hard for me to see. So we take my old Harbor Freight calipers apart and see the stator and slider.
Here are the new ones I bought thanks to the PATRONS: amzn.to/3Xh6j4y
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Gear I use:
Multimeter: OWON B33+ amzn.to/3UkTJOo
Oscilloscope: KIPRIM DS1202 amzn.to/3gfJGMN
Signal generator: Junctek JDS8080 shorturl.at/ehTZ1
Component Tester: T7 Multifunction amzn.to/3AYY03v
Soldering Station: Sealody ???????

Опубликовано:

21 сен 2024

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Комментарии : 49

@cfusername Год назад

Very interesting. Never realized these work like that. I always expected them to work like a optical mouse. But this also explains, why they are available pretty cheap, since both sides can be printed circuits.

@michaelpadovani9566 Год назад

i have a digital caliper and although I rarely use it, I had no idea how it works. Appreciate you sacrificing one to demo the inner works, thanks! Very cool.

@MyRadDesign Год назад

An important part of how the digital calipers can read to the accuracy they do is that the moving strips are a slightly different width than the fixed strips. This allows absolute positioning as well as higher accuracy much like a vernier scale is read.

@Bugsworth 2 месяца назад

Just got same from my favourite local German Supermarket for only a tenner (£). Very pleased with the quality and level of finish. Meaures to (point) 0005 of an inch, that is half of 1 thou. Now the smallest unit of measurement should be what any instrument is accurate too, so less than a thou is a lot of bang for the Bucks. Thanks for the vid, was curious what is inside, and i prolly wouldnt have got mine together again! 😀

@samkammar4763 Год назад

You're correct, calipers with a dial are called Dial Calipers. Vernier calipers just use lines like a slide rule would

@DigiLab360 Год назад

So interesting, thank you for sharing. Careful turning the electric screwdriver by hand. Had mine for 2 days and stripped the planetary gears by manually turning it. Didn't take much torque to render it completely useless.

@drescherjm Год назад

0:03 I use them at least 1 time per week for the last 3 years for something that won't be your first guess. I use them to measure the size of my wheels on my inline skates so I can find the largest 8 wheels out of (usually 16+) when I rotate the wheels. Because of my hilly terrain and skating style (practicing stopping) I need to rotate every week (or more when the wheels get low). Yesterday when I used them to measure my 3x110mm wheels the calipers were reading very wrong sizes for the first few readings. Thankfully after zeroing several times the calipers returned to working. I skate most often with a 4x90mm setup but also have 2 different 3x110 frame combinations on 2 pairs of FR1 skates.

@learnelectronics Год назад

That is a very interesting use! Thanks for sharing that!

@drescherjm Год назад

There are a couple of recommended ways to rotate 4 wheel and 3 wheel setups however the engineer in me found my own way..

@theclutteredworkbench Год назад

I have several calipers. Starett, mitutoyo, and some HF jobbers. The staretts are dial in fractions that I used for woodworking. All are pretty accurate, the HF ones were rough in the slide action, I just cleaned and lubed them. The HF ones are in my go bag and truck if I need them. Don’t care if they get beat up.

@realbogus Год назад

I ordered the caliper you recommended. It is really nice. I love the fractional display... I no longer need to do the mental math and convert... call me lazy... Quite the deal. And it seems very accurate - or - as accurate as I realistically need it to be. I already have an old and expensive micrometer. Don't need and can't justify $150+ for a caliper.

@killer2point057 Год назад

Thanks for the video! Now I don't have to destroy my pair. Still $29.98 on 06/20

@arnotek Год назад

What was that electric screwdriver you used in the video? It looks very useful.

@learnelectronics Год назад

amzn.to/3NhpSoS

@judelarkin2883 7 месяцев назад

Very interesting. It is a wonder to me that the technology can be made at the price point they make can make them at. You can expect maximum accuracy of about +/- .001 out of Starrett or Mitutoyo calipers and that is only if you are really skilled at using them. The reality is probably closer to +/- .002 if we are being honest about how carefully we measure things. You can pretty much get that with Harbor Freight calipers too. Harbor Freight calipers have other shortcomings but their accuracy isn’t really one of them.

@greggsvintageworkshop8974 Год назад

Pretty cool stuff Paul! I have the exact one you took apart. I need the one with the bigger digits for sure!

@charlesspringer4709 Год назад

I think all these are variations on the old Inductosyn patents. Is is an unwound selsyn. The cheap ones can be very accurate because they average over several loops of the "stator" coil and the PCB manufacturing process is very precise. yes, they pick up a sin (or cosine) and compare the phase angle with the driving sinusoid. That face angle can give a fraction of a degree, or a couple hundred devisions from one loop to the next of the serpentine trace. As the pickup passes over the serpentine (stator) and the phase goes from positive to negative and back. You can tell the direction of travel as well. The DSP plus the frequency used on the chip can handle any speed you move it. I have the same units and there is an output that you can solder wires to. I have looked for the source of the chips, but no luck. The same method is used for the angle measuring rulers.

@charlesspringer4709 Год назад

Well, wrong. It is a much more complicated method from the 1980's created to get around the Inductosyn patents. Ridiculously complicated if you see the software and all the signals..

@titusdocor4311 5 месяцев назад

i dont understand. I thought they measure the variation of capacitance.

@charlesspringer4709 5 месяцев назад

@@titusdocor4311It is like the two coils of a transformer and if one of them is free to turn, the phase of the output voltage will change and go through a complete cycle relative to the phase of the input. In this case the coils are unrolled and become the pattern on a printed circuit board.

@Bruces-Eclectic-World Год назад

I just checked at 10:30 est... Still $29.98 on 06/20 😃 Yes I do use one all the time. Building models I use MM all the time... I like the big screen so I will need to get one the after the 10th of the month... Who knows if they will have any by then... 🤪 Thanks for sharing! LLAP 🖖

@Johadart Год назад

Hi Paul, great video mate, love the reference to The Six Million Dollar Man at 10:02 , good job, keep up the great work. 🤙🏼🇦🇺 Joe from Australia 🤙🏼🇦🇺

@MrDoneboy Год назад

I've got one that is still in the original packaging, Paul. Just haven't needed to use it for anything!

@johnclayton2101 Год назад

Very interesting as always. I am curious. When trying to figure out the position on a motor shaft on a rotational 360 degree thing, they use some sort of encoder. I am wondering if this type of thing can be used for longitudinal position sensing. In particular, let's say I am trying to automate the position of my fence on a table saw. I have a microprocessor that controls a stepper to move the fence , but it needs a way of "Knowing" where the fence is. A digital micrometer certainly does this, on a smaller scale. I would love to learn how to bring this accuracy to and automated fence on a table saw. Look a Jeremy Fielding on RU-vid when he automated his table saw. Hope you are well, Paul. Haven't heard about your son in awhile. Penn State treating him well?

@michaeleck Год назад

Oh my, turning them into the Six-Million Dollar Calipers!🤣

@jamesbarratt593 9 месяцев назад

Have a great idea for 20 vernier calipers

@realbogus Год назад

Fascinating. Thanks for sharing!!!

@jj74qformerlyjailbreak3 Год назад

I have a dial pair and my Digital General Branded ones are just as accurate.

@aamiddel8646 4 месяца назад

Clear explanation: Some sort of oscillator....

@user5.56 Год назад

always change the battery in the calipers when u get them, that battery is used for testing & could be however old..

@bblod4896 Год назад

I prefer the older dial calipers. ☮️ brother.

@kennedygauger4680 Год назад

Paul, excellent video. I use a caliper pretty much everyday in my hobby. I find the need for greater precision. Do the high end digital calipers have more sensors that are closer together and better machining?

@learnelectronics Год назад

I honestly don't know, I have never owned a high end Starett or Mitatoyo, and when I was working they would not have let me tear one apart. My guess would be just better tolerences.

@GannDolph Год назад

I have a Carrera and a Mitatoyo. The Carrera is an all metal 'cheap' caliper. Both 6". They seem very similar in use, but the cheap ones chew thru batteries probably 100x faster. Super annoying. Maybe that's fixed on present day units. Maybe buy a quality all metal 'cheap' unit and go from there.

@olavl8827 Год назад

@@GannDolph I believe the cheap digital calipers all use basically the same circuit board, which is an old design. In principle there's nothing wrong with it except that it never really switches off. It switches off the LCD display but not the little chip that's inside. That's why they chew through batteries.

@GannDolph Год назад

@@olavl8827 makes sense. before i got the Mitatoyo my plan had been to wire in a tiny switch to the battery contacts. The Mitatoyo I have doesnt have a switch either - it turns on with a light sensor. If you flip it over or put in its case it turns off. Somehow the current draw from this is amazingly infinitesimal.

@olavl8827 Год назад

@@GannDolph The light sensor is a good idea. It could be done with just a photoresistor and a transistor. The problem is that with a little bad luck it could add perhaps a whole cent to the production cost, which the manufacturers of cheap digital calipers will of course do their best to avoid.

@nigeljohnson9820 Год назад

Might have been useful to compare the readings between the new and the old.

@learnelectronics Год назад

Sorry!

@danstheman33 7 месяцев назад

Using an electric screwdriver on tiny screws, especially cheap ones, is not a great idea.. Also, you gotta get yourself a pair of screw pliers!

@TheTrueVoiceOfReason Год назад

Grunt work... gotta make those Marines somehow pay for all those rides the Navy's given them. 😂😂 (just a little Armed Forces humor) **if I give you a basket, could you carry a tune? (Just a little musician humor) If we can't laugh at ourselves, we'll, you know the rest of that saying. Thanks Paul