Digital Vernier is now suddenly a POS

[T4P]

No, it's not as slidy as a used car salesman but it's as jumpy as a kangaroo
Sometimes it works by Zero-ing out when it begins to jump but then it doesn't work sooner or later again ... (Ah well it's only 8.82 and it's served me well for 6 months, but i guess i broke it by dropping it  )

[mikeselectricstuff]

Could be contamination on track - try taking it apart & cleaning it.

[T4P]

Could be contamination on track - try taking it apart & cleaning it.

Alcohol'd  Same issue

[SeanB]

Strip and clean, both the track and the battery terminals. Replace the batteries as well, and polish the new ones with a lint free cloth before inserting them.

[T4P]

Strip and clean, both the track and the battery terminals. Replace the batteries as well, and polish the new ones with a lint free cloth before inserting them.

I alco'd it one more time and now it's fine, the batteries alright, still the same value as a month ago

[saturation]

I don't think the 4th significant digit on digital scales is practical for common use, on digital vernier calipers.  Items one buys or fits often isn't specified to less than 0.1mm.  My manual one is over 20 years old, works with no maintenance, good to 3 significant digits.



A professional need or a production environment making many measurements daily could make errors with the manual scale and this maybe cost effective to offset the lack of robustness of digital scales.

http://en.wikipedia.org/wiki/Caliper#Comparison

If you're a stickler for absolute measures, you can go pretty high indeed, in which case a digital scale is the only way to go.

http://www.amazon.com/dp/B002SG7QM4/ref=biss_dp_t_asn

[T4P]

I don't think the 4th significant digit on digital scales is practical on digital vernier calipers.  My manual one is over 20 years old, works with no maintenance, good to 3 significant digits.

You would be surprised ... the LSB is actually the 4th digit, it's every bit accurate

[robrenz]

I don't think the 4th significant digit on digital scales is practical on digital vernier calipers.  My manual one is over 20 years old, works with no maintenance, good to 3 significant digits.

It takes extremely good technique to use that .01mm resolution of a good digital vernier in a repeatable manner.

Also a high quality 50 division vernier (inch system) that reads directly to .001" is easily interpolated by a trained eye  to .0005"

[robrenz]

You would be surprised ... the LSB is actually the 4th digit, it's every bit accurate

Be very carefull with that "accurate" word.  Consistent or repeatable might be more appropriate in this case. Traceable accuracy is the same principle in mechanical measurement as in electronic.

[SeanB]

Yes, but can it measure as big as my big one, 60cm. Bought at auction by my brother in law, who wanted the big wooden box it came in. Only goes to 0.05mm, but easy to read. Funny enough I do use it, but not often, but it is great when needed.

[rr100]

I have precisely the same model as the one from the video (or at least so it looks). I don't use it often but each time I do the batteries are flat. I have plenty of AG13s (=LR44s or whatever it uses) at hand but still silly. It has space in the case for 2 batteries, I assumed they're for spares but it seems it might be a good idea to keep the batteries out of the device when not in use anyway. Didn't read the manual, maybe this is what they expect :-)

[T4P]

I have precisely the same model as the one from the video (or at least so it looks). I don't use it often but each time I do the batteries are flat. I have plenty of AG13s (=LR44s or whatever it uses) at hand but still silly. It has space in the case for 2 batteries, I assumed they're for spares but it seems it might be a good idea to keep the batteries out of the device when not in use anyway. Didn't read the manual, maybe this is what they expect :-)

Mine hasn't dropped much since it was out of the mail
But something strikes me that i only have space for a single battery and that if you look further back and open up the gate i can find a USB plugin on the board ( i assume )

[rr100]

Sorry, mine is one battery also (really looks the same, color of the buttons, etc), I have PLACE for two spares in the foam in the box it came with.
Battery-wise I'm talking (many) months in between...
Now it's dead again, and I'm out of batteries in its box, time to get some more from the fridge :-)

[T4P]

Sorry, mine is one battery also (really looks the same, color of the buttons, etc), I have PLACE for two spares in the foam in the box it came with.
Battery-wise I'm talking (many) months in between...
Now it's dead again, and I'm out of batteries in its box, time to get some more from the fridge :-)

Yeah, it's really in "sleep" mode but that is a few nA's
Not too shabby this vernier caliper considering i really hate taking the time to read analog's ( I trust it, anyway )

[saturation]

Glad you chimed in robrenz, given your experience and professional expertise.  Yes, exactly part of my point.  Given the additional resolution, one is left with the human component of the measurement, how much force on the jaws applied to surface being measured.  So unless you're trained like a mechanical engineer to insure that resolution is repeatable and valid, extra resolution in untrained hands can be moot [ who knows if that last digit is really accurate?]

As another mention and Wikipedia article mentions, many low cost calipers have high power-off current drain.  Finally, given the quality of electronics in many Chinese made equipment, there is the added uncertainty of the longevity of device.  So, a lot of things to worry about over just a simple and functional mechanical scale, is easy to check calibration, and will work for a lifetime until the caliper is damaged or lost.

robrenz, I am almost certain you have calipers of various types, in your work are there brands that are held in high regard?  Are there best ways to calibrate lengths and weights for the layman?

I use US coins as they are widely available, make for simple checks of sizes and weights and since for everyday use at most 0.1g and 0.1mm resolution is several orders of magnitude less than the coins published specs.

http://www.usmint.gov/about_the_mint/?action=coin_specifications

It takes extremely good technique to use that .01mm resolution of a good digital vernier in a repeatable manner.

Also a high quality 50 division vernier (inch system) that reads directly to .001" is easily interpolated by a trained eye  to .0005"

You would be surprised ... the LSB is actually the 4th digit, it's every bit accurate

Be very carefull with that "accurate" word.  Consistent or repeatable might be more appropriate in this case. Traceable accuracy is the same principle in mechanical measurement as in electronic.

[SeanB]

Mass is easy, you get a set of masspieces in a box, and they come with an assize certificate. Then you have them verified by a metrology lab every few years, and handle them with care in between. I have a set of 20kg, 10kg, 5kg, 200g,100g, 50g,20g, 10g, 5g, 2g and 1g masspieces. They are certified down to 4 decimal places. I use them to verify massmeters, from precision analytical balances of 100g full scale to loadcells of 150kg full scale.

Length is also easy by using precision blocks, where they are ground to a certain length and are certified to a certain degree of accuracy, though they are only really accurate at a specific temperature. Generally they come in a set with a precision micrometer as check units to ensure that the micrometer cage is not damaged.

[rr100]

will work for a lifetime until the caliper is damaged or lost.

Funny thing I lost the first caliper I bought myself between cashier and car. That must be a record.

[robrenz]

robrenz, I am almost certain you have calipers of various types, in your work are there brands that are held in high regard?  Are there best ways to calibrate lengths and weights for the layman?

Mitutoyo absolute digimatic calipers 500-159-20 are my favorite.  They have 3.5 year battery life. They are truly absolute, you can remove the slide from the scale and it will not lose its zero (as long as it has battery power). Excellent update speed and they are much more accurate than the stated +/- .001"500-159-20

I build a diamond wheel dressing unit for a major gear grinder manufacturer where I integrate the guts of these calipers inside my unit for 5 axes of measurement that don't need a zero routine except when changing a battery.

Gage blocks are the general standard that you would use for calibration.  It depends what level you are trying to calibrate to as to what grade of gage block would be sufficient.  Grade 3 or B blocks would be sufficient to calibrate a digital caliper.  Some of the chinese sets are not to bad.  I have +/- 2u" chrome carbide blocks to check the chinese working blocks.  Yes I have 0.1u" resolution electronic gage heads to do the comparison.

[Monkeh]

I have precisely the same model as the one from the video (or at least so it looks). I don't use it often but each time I do the batteries are flat. I have plenty of AG13s (=LR44s or whatever it uses) at hand but still silly. It has space in the case for 2 batteries, I assumed they're for spares but it seems it might be a good idea to keep the batteries out of the device when not in use anyway. Didn't read the manual, maybe this is what they expect :-)

Stop feeding it LR44s, then. It wants SR44s.

[T4P]

I have precisely the same model as the one from the video (or at least so it looks). I don't use it often but each time I do the batteries are flat. I have plenty of AG13s (=LR44s or whatever it uses) at hand but still silly. It has space in the case for 2 batteries, I assumed they're for spares but it seems it might be a good idea to keep the batteries out of the device when not in use anyway. Didn't read the manual, maybe this is what they expect :-)

Stop feeding it LR44s, then. It wants SR44s.

Yeah, LR44's have a short life that's all
I believe the better ones have SR44's installed instead

[rr100]

It says specifically LR44 in the manual, not that SR44 would hurt. Will pick some next time.
I'm used with (small) clocks that will go for quite a while on LR44s. Measured now the consumption, it's 14 microamps, no matter if it's on or off!!!
Probably with SR44 I'll get rid of the "dead again" symptom for the next few years but so will keeping the battery beside it in the box :-)

[Psi]

My vernier is almost identical to yours and i've have issues of it jumping around before

The cause has always been the battery and/or battery contacts.
Most of the time they just need a clean, if the voltage gets low it starts jumping around.

[T4P]

It says specifically LR44 in the manual, not that SR44 would hurt. Will pick some next time.
I'm used with (small) clocks that will go for quite a while on LR44s. Measured now the consumption, it's 14 microamps, no matter if it's on or off!!!
Probably with SR44 I'll get rid of the "dead again" symptom for the next few years but so will keeping the battery beside it in the box :-)

I assume Sliver Oxide won't leak like Alkaline does. Anyway 14uA means the LCD .... never draws but the 8bit uC never sleeps !

My vernier is almost identical to yours and i've have issues of it jumping around before

The cause has always been the battery and/or battery contacts.
Most of the time they just need a clean, if the voltage gets low it starts jumping around.

Mine was the capacitive track (i think)

[rr100]

I assume Sliver Oxide won't leak like Alkaline does. Anyway 14uA means the LCD .... never draws but the 8bit uC never sleeps !

You mean leak as in leaking fluid or self discharge? Either way I'm rather pleased with the (random brand) cheapo LR44s (/AG13) and I'm using them for uh, probably "tens of years" would be correct (man I'm old). I have a small clock+thermometer, a portable clock/alarm/calculator and probably some more things and they just go on forever (well not like a simple CR2032 watch for 10+ years, but enough not to matter, like 1-3 years). I have some more random crap (scientific calculators and such) but nothing else that I regularly use. So probably self-discharge won't be a problem, but just parasitic drain would (for my calipers mentioned).
Oh, wait funny thing: I do have one more thing that eats 44's like there's no tomorrow: one of these kill-a-watt meters. It has two LR44s to keep settings (including clock) while it's unplugged but probably they got sloppy and left it with a high "off" current. Or they just designed it to rely on batteries when you unplug it and plug it in another socket, for just minutes at a time. In fact I need to check, maybe the design is so horrendous that it eats batteries even when it's plugged into mains. Well, not so bad in fact, I use the "autoreset when unplugged" as a function nowadays instead of fiddling with the buttons to reset it (and I ignore all the other functions like clock+night kWh prices, etc)

[T4P]

You mean leak as in leaking fluid or self discharge? Either way I'm rather pleased with the (random brand) cheapo LR44s (/AG13) and I'm using them for uh, probably "tens of years" would be correct (man I'm old). I have a small clock+thermometer, a portable clock/alarm/calculator and probably some more things and they just go on forever (well not like a simple CR2032 watch for 10+ years, but enough not to matter, like 1-3 years). I have some more random crap (scientific calculators and such) but nothing else that I regularly use. So probably self-discharge won't be a problem, but just parasitic drain would (for my calipers mentioned).

Fluid discharge

I just read up that alkaline 44's discharge faster (lower capacity) but also because the voltage drops more then the sliver oxide equivalents
(Alkaline's internal resistance rises very quickly)