Author Topic: digital vernier callipers  (Read 4177 times)

Re: digital vernier callipers
« Reply #50 on: July 25, 2019, 01:26:54 pm »
@Randy: AVE has a turn of phrase, doesn't he?

He's really funny. I've been following him for a while. I wonder what he does for a living? Some kind of engineering I think.
I think you'll find it's a bit more complicated than that.

T42

  • Tea tank
Re: digital vernier callipers
« Reply #51 on: July 25, 2019, 04:41:59 pm »
If it's not been wet and the battery's okay, it's probably the usual LCD zebra strip or hot-bar connection problems, which are somewhere between a pain in the arse to troubleshoot and impossible to fix.  I bet there are important mechanical pingfuckits that will break if you attempt to get inside, too.

Par for the course with el cheapos.  Well, for < 10€ I'm not crying.
I've dusted all those old bottles and set them up straight.

Re: digital vernier callipers
« Reply #52 on: July 25, 2019, 04:57:10 pm »

I checked my battery and it's down from 1.5v to 1.0, which should still be functional....


try a new battery; 1V (with no load) means the battery has had it.

cheers

Re: digital vernier callipers
« Reply #53 on: August 11, 2019, 08:34:26 am »
Lidl have got their digital calipers in at the moment, £8.

I was tempted, but didn't buy.

T42

  • Tea tank
Re: digital vernier callipers
« Reply #54 on: August 11, 2019, 10:40:38 am »

I checked my battery and it's down from 1.5v to 1.0, which should still be functional....


try a new battery; 1V (with no load) means the battery has had it.

cheers

Aha! Cheers indeed. Will do.
I've dusted all those old bottles and set them up straight.

T42

  • Tea tank
Re: digital vernier callipers
« Reply #55 on: August 20, 2019, 09:02:50 am »

I checked my battery and it's down from 1.5v to 1.0, which should still be functional....


try a new battery; 1V (with no load) means the battery has had it.

cheers

Well, it took me this long to scare up a new battery*, and the result is...

Thank you very much! It worked!


* after two shopping trips with LR44 on the list we came home empty-handed. Finally I found a card of them in a drawer in the kitchen: "best before 2012". They still develop >1.5v on no load and the calliper works. I'm still getting new ones, though.
I've dusted all those old bottles and set them up straight.

Re: digital vernier callipers
« Reply #56 on: August 20, 2019, 09:38:16 am »
eBay is your friend for such things, interestingly most seem to be in the UK

https://www.ebay.fr/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR11.TRC1.A0.H0.XLR44.TRS0&_nkw=LR44&_sacat=0

Re: digital vernier callipers
« Reply #57 on: August 20, 2019, 10:12:43 am »
Well, it took me this long to scare up a new battery*, and the result is...

Thank you very much! It worked!


* after two shopping trips with LR44 on the list we came home empty-handed. Finally I found a card of them in a drawer in the kitchen: "best before 2012". They still develop >1.5v on no load and the calliper works. I'm still getting new ones, though.

good work fella!

FWIW a long time ago I bought some cheap digital verniers and these showed 'low battery' with a flashing display whenever the thing wasn't 100% happy with the battery voltage. This seemed to happen very quickly even with a brand new battery installed.  Turns out there are several types of battery that are slightly different chemistry and have the same dimensions/polarity and often these are sold as 'equivalent' when this is not exactly true.   IIRC the thing is set up with Silver Oxide chemistry in mind, which is slightly higher voltage than an alternative (but much more commonplace)  alkaline chemistry.   If you fit the latter type of battery in these calipers the low battery indication starts flashing after just a few hours use, which is annoying. However I came to realise that the calipers would still work for a very long time with an alkaline cell (and  the low battery indication on), before they would finally conk out.  So with these calipers/batteries it turns out that they work fine @ ~1.25V (but with a flashing display) but if the battery gets down to ~1.1V then they really do clap out.

Knowing what voltage a device will work at, and what the symptoms are of (true) low battery voltage seems very useful to me.

cheers

T42

  • Tea tank
Re: digital vernier callipers
« Reply #58 on: August 20, 2019, 11:00:32 am »
eBay is your friend for such things, interestingly most seem to be in the UK

https://www.ebay.fr/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR11.TRC1.A0.H0.XLR44.TRS0&_nkw=LR44&_sacat=0

They're available in the supermarkets here all right, but first trip they were all gone and they didn't get put back on the list for the second one.  :facepalm:


Well, it took me this long to scare up a new battery*, and the result is...

Thank you very much! It worked!


* after two shopping trips with LR44 on the list we came home empty-handed. Finally I found a card of them in a drawer in the kitchen: "best before 2012". They still develop >1.5v on no load and the calliper works. I'm still getting new ones, though.

good work fella!

FWIW a long time ago I bought some cheap digital verniers and these showed 'low battery' with a flashing display whenever the thing wasn't 100% happy with the battery voltage. This seemed to happen very quickly even with a brand new battery installed.  Turns out there are several types of battery that are slightly different chemistry and have the same dimensions/polarity and often these are sold as 'equivalent' when this is not exactly true.   IIRC the thing is set up with Silver Oxide chemistry in mind, which is slightly higher voltage than an alternative (but much more commonplace)  alkaline chemistry.   If you fit the latter type of battery in these calipers the low battery indication starts flashing after just a few hours use, which is annoying. However I came to realise that the calipers would still work for a very long time with an alkaline cell (and  the low battery indication on), before they would finally conk out.  So with these calipers/batteries it turns out that they work fine @ ~1.25V (but with a flashing display) but if the battery gets down to ~1.1V then they really do clap out.

Knowing what voltage a device will work at, and what the symptoms are of (true) low battery voltage seems very useful to me.

cheers


Well, I know now.

My calliper came with a couple of batteries. When the first one began to die the display just got a bit fainter, but with the second one it went bonkers and the buttons didn't work.  I hadn't used the thing for a while, so I suppose the 2nd battery had run down a bit further.  I suppose such devices don't really switch off.
I've dusted all those old bottles and set them up straight.

Feanor

  • It's mostly downhill from here.
Re: digital vernier callipers
« Reply #59 on: August 24, 2019, 09:59:23 am »
Yes, my bike power meter is similar in that it never truly goes off. It goes into some standby and is woken by spinning the cranks.

The instrustions are very specific about using Renata brand cells, and it does make a difference. Other brand cells will show low battery very quickly. Must be a different chemistry.

TheLurker

  • Goes well with magnolia.
Re: digital vernier callipers
« Reply #60 on: August 24, 2019, 02:50:40 pm »
Quote from: T42
...  I suppose such devices don't really switch off.
One wonders (idly) if this is a cheap way (for the manufacturer, not the owner) to retain device calibration settings between periods of use.  Maintain the calibration info. in cheapo DRAM and keep refreshing* it rather than having to muck about including some more expensive non-volatile storage and the associated gubbins to update it.



*One understands some whizzy new DRAM even has its own refresh circuitry which I assume makes designing the circuitry for such kit even easier and probably even cheaper to assemble.
Τα πιο όμορφα ταξίδια γίνονται με τις δικές μας δυνάμεις - Φίλοι του Ποδήλατου

Kim

  • Timelord
Re: digital vernier callipers
« Reply #61 on: August 24, 2019, 03:01:33 pm »
Quote from: T42
...  I suppose such devices don't really switch off.
One wonders (idly) if this is a cheap way (for the manufacturer, not the owner) to retain device calibration settings between periods of use.  Maintain the calibration info. in cheapo DRAM and keep refreshing* it rather than having to muck about including some more expensive non-volatile storage and the associated gubbins to update it.

Unlikely.  It'll be some bog standard generic off the shelf microcontroller.  The cheap off-the-shelf microcontrollers are the ones made in huge quantities, generally because they're engineered to be suitable for a zillion applications, including battery-powered ones where low power is important.

Expect SRAM and EEPROM, and a sleep mode that gets the current consumption down to a few nano-amps.  That can be less than the self-discharge of many battery chemistries (though probably not the sort of primary lithium cells that tend to get used in tools like these).  The main issue becomes how often the software wakes from sleep to see if a button's been pressed.
Careful, Kim. Your sarcasm's showing...

Re: digital vernier callipers
« Reply #62 on: August 24, 2019, 06:34:40 pm »
Quote from: T42
...  I suppose such devices don't really switch off.
One wonders (idly) if this is a cheap way (for the manufacturer, not the owner) to retain device calibration settings between periods of use.  Maintain the calibration info. in cheapo DRAM and keep refreshing* it rather than having to muck about including some more expensive non-volatile storage and the associated gubbins to update it.

Unlikely.  It'll be some bog standard generic off the shelf microcontroller.  The cheap off-the-shelf microcontrollers are the ones made in huge quantities, generally because they're engineered to be suitable for a zillion applications, including battery-powered ones where low power is important.

Expect SRAM and EEPROM, and a sleep mode that gets the current consumption down to a few nano-amps.  That can be less than the self-discharge of many battery chemistries (though probably not the sort of primary lithium cells that tend to get used in tools like these).  The main issue becomes how often the software wakes from sleep to see if a button's been pressed.

My understanding is that it is to do with maintaining calibration. Something to do with the cheaper units only being able to measure relative movement, so that if they truly switched off you'd have to re-zero them every time.

The more expensive ones apparently work in a different way and know where they are in absolute terms.

Kim

  • Timelord
Re: digital vernier callipers
« Reply #63 on: August 24, 2019, 07:32:22 pm »
Sure, but why would anyone use DRAM when you can use SRAM, EEPROM or flash memory?

Design considerations such as the cheapness of membrane pushbuttons vs physical on/off switches may be as important as the ability to retain calibration.
Careful, Kim. Your sarcasm's showing...

Vince

  • Can't climb; won't climb
Re: digital vernier callipers
« Reply #64 on: August 24, 2019, 10:03:41 pm »
Is it just me for whom "Digital vernier caliper" grates? Surely the caliper is either digital or vernier.

Having both types, once I had learned how to read a vernier scale, it has become my go to measuring tool.
216km from Marsh Gibbon

Re: digital vernier callipers
« Reply #65 on: August 24, 2019, 10:19:33 pm »
Sure, but why would anyone use DRAM when you can use SRAM, EEPROM or flash memory?

Design considerations such as the cheapness of membrane pushbuttons vs physical on/off switches may be as important as the ability to retain calibration.

I'm not sure I'm following you. If you are suggesting a lower power way of retaining memory I can't see how that would help.

The cheaper calipers aren't always-on to retain memory, they are always-on so that they can constantly track their opening and closing. Otherwise if you switched one off, opened it up a bit, then switched it on the zero would be incorrect. You could just zero it every time you turned it on of course but that's not how they are made.

I believe the better calipers have some difference in the track that lets the electronics know exactly how it's set, even from a proper power-off.

Re: digital vernier callipers
« Reply #66 on: August 24, 2019, 10:20:52 pm »
Is it just me for whom "Digital vernier caliper" grates? Surely the caliper is either digital or vernier.

It's not just you  ;)

T42

  • Tea tank
Re: digital vernier callipers
« Reply #67 on: August 25, 2019, 08:47:41 am »
Yeah, ditto. Trouble is that calliper denotes a whole class of devices, and unless you add vernier the sliding-scale variety doesn't come to mind. E.g. I could imagine a digital version of hinged callipers (which would be very useful, too).
I've dusted all those old bottles and set them up straight.

mattc

  • n.b. have grown beard since photo taken
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Re: digital vernier callipers
« Reply #68 on: November 24, 2019, 07:02:04 pm »
<slight thread reheating ...>

Draper do a CF version of their 6" product which is way cheaper than the normal one:
https://www.drapertools.com/product/24816/150mm-or-6inch-Carbon-Fibre-Digital-Caliper-Gauge

I'd never heard of CF being used for jaws/parts before - there MUST be a drawback if they are so much cheaper. Surely??
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

Re: digital vernier callipers
« Reply #69 on: November 24, 2019, 07:09:21 pm »
If they're like the cheap "carbon fibre" ones on eBay, it's just bendy plastic and they flex so much you're mostly measuring your finger pressure.

Kim

  • Timelord
Re: digital vernier callipers
« Reply #70 on: November 24, 2019, 07:15:17 pm »
Probably useful for measuring magnets...
Careful, Kim. Your sarcasm's showing...

Re: digital vernier callipers
« Reply #71 on: November 24, 2019, 07:18:40 pm »
And for delicate easily scratched stuff.

Re: digital vernier callipers
« Reply #72 on: November 24, 2019, 07:35:20 pm »
FWIW I have more than one set of digital verniers which are either used very intermittently or where the battery only lasts six months or so.  I have used cheap batteries (eg from the pound shop) but it still irks me that the batteries clap out so quickly.  It also irks me that I end up with various batteries that I don't need when I buy a card of them from the pound shop.

So my latest wheeze is to use some of the thinner batteries (which are otherwise the correct diameter, voltage and polarity) together with a spacer such as an 'O' ring to make up the thickness difference. If I am not going to use the calipers for a week or so, I'll take the O ring out (which usually moves the battery off its seat and turns the thing off) and I then stow the O ring somewhere convenient like over the locking screw knob.  Hopefully if I do this I won't be having to change the battery so often, and I won't be left with so many batteries that I'm never going to use.

Of course I'd be even happier with a proper 'off' switch but I suppose that would cost money....

cheers

cheers

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: digital vernier callipers
« Reply #73 on: November 24, 2019, 07:36:44 pm »
And for delicate easily scratched stuff.
... and cells*

(*batteries for some of you plebs :P )

If they're like the cheap "carbon fibre" ones on eBay, it's just bendy plastic and they flex so much you're mostly measuring your finger pressure.
Yeah, I did stumble on some comments about such things! But Draper are a pukka company ... aren't they?  :-\
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

Re: digital vernier callipers
« Reply #74 on: November 24, 2019, 07:52:51 pm »
They might have been once but there main business these days is sticking their logo on imported TSOs.