Caliper with/without fine adjustment?

[Gyro]

But yeah, you may have a point. Maybe I'm weakening - maybe I'll go digital. The ghosts of my youth are returning to torture me - 5 years of slide rules before using a calculator leave a deep impression on a man - the thought of buying a digital caliper feels a bit like cheating.

Don't forget to buy a digital watch at the same time! 

“Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-two million miles is an utterly insignificant little blue green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.”

― Douglas Adams, The Hitchhiker's Guide to the Galaxy

[chris_leyson]

@ aneevuser, if you need to make a lot of measurements either in metric or imperial with a resolution of 0.01mm then by all means get a Mitutoyo digital caliper, they are well built, very easy to read and the batteries last a long time, about £110 from Farnell. On the other hand, a classic Vernier scale Mitutoyo will cost £32 or £38 for 0.05mm and 0.02mm resolution respectively. The fine adjustment feature is useful if you want to measure small differences. The only draw back with classic Vernier calipers is that I now have to use a x10 magnifier to make use of the 0.02mm resolution. If you don't want to go digital then I would recommend Mitutoyo 150mm dial calipers, much easier to read and 0.01mm resolution. At work I use a Mitutoyo dial caliper because the display isn't cracked and there is no ty-wrap holding the battery compartment in place.

[drussell]

You are allowed to own multiple calipers, you know.   

Yes, but in these post-COVID times, money is scarce, so I'd rather buy a decent tool just the once.

Just don't go crazy and start hoarding test & measurement equipment or you'll end up like those nutters over in the TEA thread. 

No chance - I have the personality to do so, but not the cash.

I realize money is tight right now, believe me, I know!  You don't necessarily need to spend a lot of money for something decent and perfectly usable, though.  Just please try to get something better than these or these:



I bought one of the various versions of plastic(!!) digital Power Fister brand caliper one time on sale for $4.99 and although I've probably got my $5 out of it over the years, I don't really recommend doing that.    They sit on top of my fridge in the kitchen beside a tape measure for random household measurements.

Astoundingly, though, the fact that they've got a regularly-priced sub-$14 stainless digital makes me want to buy one just to see how terrible it is.  I'll bet if it were disassembled, de-burred, properly cleaned of machining residue, lightly oiled and re-assembled, it would probably be far more useful than the plastic one in the kitchen.    If I ever see one of those on sale for 50% off for $7 sometime when I'm at Princess Auto, it'll be very, very difficult to resist the urge to buy one.


... but then again, I follow the TEA thread even though I don't hoard multimeters, frequency counters or oscilloscopes.  I'm trying to avoid becoming an addict like those junkies.   I certainly can't afford their habit! 

[Kjelt]

Maybe I'm weakening - maybe I'll go digital. The ghosts of my youth are returning to torture me - 5 years of slide rules before using a calculator leave a deep impression on a man - the thought of buying a digital caliper feels a bit like cheating.

Cheating ? It has higher accuracy (0.01 vs 0.05 or 0.02 with guestimate) and I don't know how good you're vision is but locking the slider and then removing the calliper before having a good view to interpolate between the last digits can also divert the measurement.
Bedn there done it fir twenty five years, went digital and never looked back.
Even with a measurements clock where an analogue dial gives a better insight in tolerances when moving, a digital one with large display is also very handy for many measurements at distance. You decide, your money, just sharing my personal experience and preference with both.

[Kjelt]

I'll give you an example , the first two are 30,00 mm.
Now you tell me the third 

[coppercone2]

those plastic calipers are a good idea if you are positioning stuff with glue on it (i.e. you coat something with glue and you position it near where it needs to be then move it around on a X-y axis to get it to a particular position by poking it and then clamping it. You don't want to forget epoxy on a real caliper).

Normally you would use a adjustable square to poke things, but I can see a plastic caliper being useful for small things gently riding on glue.

[CatalinaWOW]

It has been mentioned, but it is worth repeating.  What are you doing and what accuracy do you need?  I use dial calipers by preference and have no problem setting them within 0.001 inch (0.025 mm) using a thumbwheel.  By that I mean less than a quarter of the space between graduations.  Doing it without the thumbwheel is a bit tougher, requires some technique but still not out of line.  No need for a fine adjustment screw.

My actual measurement requirements tend to be well larger than those tolerances in almost all cases.  The only time accuracies approaching that are necessary is when fitting dowel pins into holes and the like, and even there other problems like burrs, eccentricity of the parts and the like rapidly become the dominant errors.

I suspect you will do just fine without the fine adjustment screw, but again, your needs may be different.

[drussell]

those plastic calipers are a good idea if you are positioning stuff with glue on it (i.e. you coat something with glue and you position it near where it needs to be then move it around on a X-y axis to get it to a particular position by poking it and then clamping it. You don't want to forget epoxy on a real caliper).

Oh, absolutely.  Those cheap blue ones are great for certain purposes but measuring crankshaft bearing shell thickness is not one of them. 

I'm sure I still have my very first light blue Radio Shack plastic vernier ones from the late '70s or early 80s around somewhere, my very first calipers that I got as a kid.  No idea where they are right now, probably in some desk drawer somewhere around here, but I still remember being astounded at the accuracy you could measure to with the vernier as a kid.  The concept of aligning the lines to get accurate measurements just absolutely blew my mind.  Brilliant!

Of course, for plastic vernier ones, they were reasonably well built back then, with actual scribed/engraved/molded-in lines filled with paint instead of cheap Chinese silk screening that will rub off if you look at it wrong like those PowerFist ones shown above.  Still probably well worth it when you might need a "disposable" caliper, though.

[chris_leyson]

Now you tell me the third 

I would say 1.02mm or 1.03mm just by eye. A digital gauge still has to translate a linear displacement using a capacitive encoder. Resolution is one thing but accuracy needs to taken into account as well as zero offset and temperature. I have a Mitutoyo analogue dial gauge that will do 10um per division with 2um accuracy at 20C, it's purely mechanical with no added cost of a digital encoder.

[Kjelt]

Now you tell me the third 

I would say 1.02mm or 1.03mm just by eye.

If you look again you see the bar between the 0 and the 1 almost exactly on mark which means best guess would be around 1.05mm.
That is because the mechanical caliper has an accuracy of 0.05mm the rest is best guess.
The digital caliper has an accuracy and repeatability of 0.01-0.02mm and it is pretty accurate over the entire range of 0-150mm which I checked with calibers.

[drussell]

Now you tell me the third 

I would say 1.02mm or 1.03mm just by eye.

If you look again you see the bar between the 0 and the 1 almost exactly on mark which means best guess would be around 1.05mm.
That is because the mechanical caliper has an accuracy of 0.05mm the rest is best guess.
The digital caliper has an accuracy and repeatability of 0.01-0.02mm and it is pretty accurate over the entire range of 0-150mm which I checked with calibers.

From the angle in the photo, it actually looks like it's shifted ever so slightly to the left, so I would have guessed about 1.04mm, but that's just the thing with vernier calipers.  They can be extremely accurate but it takes far longer to read each measurement and you have to hold both the caliper and your nose at just the right angle, then stroke your beard thusly, in order to get anywhere close to a fine-grained measurement. 

Obviously, this level of detail is rarely required in actual practice for most things, but as soon as you use a digital you'll probably never want to go back to anything else.    A quality dial indicator or dial caliper excepted, perhaps.  Those are still super swanky, too.  Interestingly, I don't own any digital indicators, and don't see any need to get one, yet have several dial indicators, but they're really used for different purposes than a caliper, and you don't want to be actually touching them in any way while taking a measurement anyway....  but I digress.... 

I bought my original (and still probably the best digital I own) no-name digital caliper from a local auto parts & tools supplier on special order in 1992 or 1993.  I was trying to decide between buying a small set of micrometers or these new-fangled digital calipers.  It was a close to a couple hundred bucks either way, and neither was quite Mititoyo grade, but the counter sales guy convinced me to special order the digital caliper instead of buying the mic set they had, and I've been grateful ever since for making that choice. 

Obviously, the best tool for the job really depends on the application, but folks like us tend to have a wide variety of use cases, so something that is good to excellent in most average cases is the winner, IMHO.

YMMV!

[tautech]

Good vernier calipers will last a lifetime when cared for yet your eyes won't. 
Get some dial or digital ones in preparation for old age.

In use here:
Plastic................real POS and only used for approximate measurements....faster than engineers dividers and a steel ruler. 
Cheap stainless verniers (~$15 IIRC) on the reloading bench as 'good enough' for those tasks.
Imp dial calipers at the lathe in the workshop as quick and simple and accurate enough for most tasks.
Cheap digitals in a plastic case and here on the bench that float to wherever more accurate measurements are required.

[aneevuser]

OK folks, the decision is made, no more arguments are needed - I ordered an iGaging digital caliper.

[eKretz]

Verniers are pretty easy to read accurately, but it does take longer than a digital to do so. If you have hundreds of parts to measure that can add up to a not insignificant amount of time. The "hold everything just so"  method isn't really necessary, one merely needs to ensure that the eye is looking straight down on the graduations to avoid what is known as parallax error. Analog multimeters are no different and this is the reason for the mirror behind the needle - when you can't see any more than one needle you are looking straight down. Better verniers have both scales inline with each other rather than one overlapping the other to avoid this problem. Notice that the Mitutoyo shown above does not have this feature but they did bevel the face of the vernier scale so it's almost on the same level as the main scale. This helps but will not completely eliminate parallax issues.

All of that said, and having plenty of both types of caliper, I'd go with a digital if you're only getting one. I see that decision has already been made, and it was a good one.

[Electro Fan]

OK folks, the decision is made, no more arguments are needed - I ordered an iGaging digital caliper.

Congrats - Plz let us know what you think after you have used it a few times.  I’m betting you are going to be really happy at first and then more happy each time you use it to solve for something else as you do various projects.  After your first half dozen or so projects with it you will wonder why it took you so long to adopt it and why everyone doesn’t have one.  Just my guess - YMMV, but that’s the prediction. 

[aneevuser]

Congrats - Plz let us know what you think after you have used it a few times.  I’m betting you are going to be really happy at first and then more happy each time you use it to solve for something else as you do various projects.  After your first half dozen or so projects with it you will wonder why it took you so long to adopt it and why everyone doesn’t have one.  Just my guess - YMMV, but that’s the prediction. 

OK, here's an update. I've received the iGaging caliper(s?) and have made a few measurements that I wanted to make - these needed sub-mm accuracy so the 0.01 mm accuracy that I get is currently irrelevant; however I needed the calipers for the jaws and depth measurement. They cost me about £37 including delivery.

1) the build and general fit-and-finish is good - no visible gap between jaws when closed; very smooth movement with no rough spots; returns to 0 when jaws are closed with almost 100% reliability (very occasional 0.01 mm error). The only noticeable weak point is the thumb wheel, which catches on the body from time to time when engaged, and a perhaps 0.01 mm discrepancy between end-of-outer-jaws and center-of-outer-jaws.

2) I've only ever used manual verniers before; I find that the real-time feedback of distance to an accuracy of 0.01 mm is slightly disturbing - tiny motions change the numbers and make me feel that I'm making an incorrect measurement - I think that, at the moment, I prefer the set/remove/read process of a manual tool.

3) I'm not mad keen on the added bulk of the display/control box - I feel that it could get in the way of jaw placement in confined spaces.

Overall, these are very nice, and I'm glad that I bought them...however, yeah, they're nice. A bit too nice to use in a cold garage where they could be damaged, maybe? So I'm now thinking that I want some cheap vernier calipers that I care less about, with say 0.1 mm accuracy, which will be OK for many measurements that I want to do. So I've bought, also, a set of the real cheap plastic calipers listed upthread, just to see how cheap you can go. (I got them for £1.89 including delivery, so yes, they're cheap - I also saw them being used on that Youtube channel where the Finnish guy crushes things with a press, which piqued my interest). 

And, it's quite amazing (to me) but with a bit of care, I can get about 0.1 mm accuracy (as checked by the iGaging) with the cheapo plastic things - with the outside jaws at least - depth measurement is about 1 mm off, so useless. The smaller pink/orange one is actually better than the larger grey one - the larger grey one gives an error of -6 thou when closed, on the mm scale (yes, I only had an imperial feeler gauge to check with), but I can fix that up with a bit of aluminium foil or something. I've spent some time checking between the plastic junk and the iGaging magnificence, and I'm reliably able to measure to about +/- 0.15 mm with the plastic things.

So that's the current state of play - if I can find some 10 quid steel verniers that reliably measure to 0.1 mm, I'd be even happier, but I think that at that price point, you can buy unusable junk on the internet and simply be 10 quid down - hardly matters for £1.89 though.

[CatalinaWOW]

And, it's quite amazing (to me) but with a bit of care, I can get about 0.1 mm accuracy (as checked by the iGaging) with the cheapo plastic things - with the outside jaws at least - depth measurement is about 1 mm off, so useless.

If the 1 mm error is consistent it isn't useless, just inconvenient.  If your memory doesn't support storing the error for correction purposes, use a sharpie to write it on the caliper.  One thing that plastic excels at is retaining those markings.

[aneevuser]

If the 1 mm error is consistent it isn't useless, just inconvenient.  If your memory doesn't support storing the error for correction purposes, use a sharpie to write it on the caliper.  One thing that plastic excels at is retaining those markings.

Yes, I could do that, though having done similar in the past, I'm not too keen on having to apply a correction to each measurement. (I'll remember about 95% of the time...)

I may be able to lengthen the depth gauge with some effort, if I can be bothered. Annoyingly, both calipers have the depth gauge too short, so it's not a matter of filing them down.

[CatalinaWOW]

If the 1 mm error is consistent it isn't useless, just inconvenient.  If your memory doesn't support storing the error for correction purposes, use a sharpie to write it on the caliper.  One thing that plastic excels at is retaining those markings.

Yes, I could do that, though having done similar in the past, I'm not too keen on having to apply a correction to each measurement. (I'll remember about 95% of the time...)

I may be able to lengthen the depth gauge with some effort, if I can be bothered. Annoyingly, both calipers have the depth gauge too short, so it's not a matter of filing them down.

If you are feeling bold, there may be enough meat to file the body down.  Another bodge with only a couple of pounds to lose is to use your soldering iron to embed piece of piano wire into the end of the depth probe and then file that down.  This is all just for the fun of it.  You have a good one when you need it.

[KL27x]

they're nice. A bit too nice to use in a cold garage where they could be damaged, maybe?...

You just have to treat your iGaging like they cost 10 quid, and your problems are over.
If you can't do that, what good would Starett or Mitt calipers do a guy besides keeping the pin gauges company in the bottom of a drawer?

That would be a little like splurging on a solid gold toilet but caring about the cost. Then you have to take a crap... but not in THAT toilet!

Use 'em like you stole 'em. That's how you get a return on your investment. If they break the first time you drop them, then you'll know you paid too much, lol.

I've dropped my digital calipers onto concrete many a time, and they're still just as accurate as ever. Depending on how they hit, you might have to stone the tip of the jaws. Or you might need to replace a cracked LCD cover with plexiglass. But I'm not gonna stop to find my "cheap calipers" to make a measurement. Even if I'm making a part to fix something that costs $5.00, I'm using these 0.001" digital calipers to take measurements. (Actual example, making a new plastic piston bit that goes in an air compressor blow gun that started leaking excessively). If I dropped my precious Mitts in the garage while doing that, I suppose I should cry.