Yet Another Cycling Forum

General Category => The Knowledge => OT Knowledge => Topic started by: canny colin on May 20, 2019, 09:15:02 am

Title: digital vernier callipers
Post by: canny colin on May 20, 2019, 09:15:02 am
Looking for recommendations for above , mainly for measuring bearing sizes on bikes ect .  Close up vision is not what it was . Are cheaper £15  / £ 25  callipers worth having Thanks colin   
Title: Re: digital vernier callipers
Post by: Brucey on May 20, 2019, 09:20:41 am
the ones from Aldi are very good for the money. They are not super-smooth when they are new but free up with use/fettling. BTW I have owned and used posher ones (e.g. Mitutoyo) and I wouldn't bother with anything like that for bicycle work.

[edit; they are obviously not available all year round but (in last year's version) they  do have big numbers in the display, and have a good (battery saving) auto on/off facility.]

(https://www.aldi.us/fileadmin/fm-dam/Weekly_Assets/2014/SB-3-26/032614_91074_DigitalCaliper_D.jpg)

cheers
Title: Re: digital vernier callipers
Post by: grams on May 20, 2019, 09:23:30 am
Get one with a metal body. The black plastic ones are too bendy to measure anything even mildly accurately.

Otherwise they’re all pretty much the same.
Title: Re: digital vernier callipers
Post by: T42 on May 20, 2019, 09:27:49 am
I'm happy with my 9€ eBay calliper, e.g. it measures drill shank diameters to within 0.03 of a mm from the stated value, which is probably inaccurate anyway.

Main issue with such callipers is manufacturing tolerances, which you can judge by seeing how consistently they measure the same thing.  I use mine for everything bikish plus luthiery and I've no complaints.

Get one with a metal body. The black plastic ones are too bendy to measure anything even mildly accurately.

Otherwise they’re all pretty much the same.

Not with a bargepole.
Title: Re: digital vernier callipers
Post by: fuaran on May 20, 2019, 09:42:12 am
I've got one from Lidl, cost about £9 I think. Works fine for me.
Title: Re: digital vernier callipers
Post by: Ham on May 20, 2019, 10:55:46 am
I have a "Powerfix" branded one from Lidldi, I'm amazed how well machined the jaws are, to within .02mm by all accounts. Dated 2010, still 100% OK.
Title: Re: digital vernier callipers
Post by: Wobbly John on May 20, 2019, 11:10:57 am
the ones from Aldi are very good for the money. They are not super-smooth when they are new but free up with use/fettling. BTW I have owned and used posher ones (e.g. Mitutoyo) and I wouldn't bother with anything like that for bicycle work.

[edit; they are obviously not available all year round but (in last year's version) they  do have big numbers in the display, and have a good (battery saving) auto on/off facility.]

(https://www.aldi.us/fileadmin/fm-dam/Weekly_Assets/2014/SB-3-26/032614_91074_DigitalCaliper_D.jpg)

cheers

The ones I bought from Aldi this year were crap, and I took them back because they were unusable due to poor contact problems.
Title: Re: digital vernier callipers
Post by: Brucey on May 20, 2019, 11:21:29 am

The ones I bought from Aldi this year were crap, and I took them back because they were unusable due to poor contact problems.

that is unfortunate, I wonder how common such problems are/were?

FWIW I bought four sets in 2018 and they were all the same; a bit too stiff when new but eased up with use/fettling. I gave one set away and the others I've used/abused in various ways. At that price I don't mind grinding the jaws weird shapes so that I can use them to measure odd things.

One thing that I didn't mention is that IME all basic digital verniers are not at all tolerant of moisture; if they get wet they are usually no good at all, sometimes permanently.  One of the few uses where I'd spend the money on a posh set might be if I were doing more lathe work (with water-based coolant) where a waterproof set would be a significant advantage.

cheers
Title: Re: digital vernier callipers
Post by: Kim on May 20, 2019, 11:32:13 am
My Aldi ones from some years ago arse still going strong (though the hinge of the box has snapped).  They've had at least one fresh battery in that time.
Title: Re: digital vernier callipers
Post by: Jurek on May 20, 2019, 11:58:32 am
I'm surprised as to how long the battery lasts in my Mitutoyo callipers, given that more often than not they go back in the box still switched on. I've probably had them the best part of 25 years, and cannot remember replacing the battery more than twice.
Title: Re: digital vernier callipers
Post by: T42 on May 20, 2019, 12:58:16 pm
I just compared my 9€ callipers against true vernier callipers I bought for Frs.lots away back and they agree in the second decimal place of mm. And the digital ones can be switched to imperial, which is useful at times.

I've already gone through one battery in 2 years, but IIRC they came with the battery installed.  A second one was included - nice.
Title: Re: digital vernier callipers
Post by: andytheflyer on May 20, 2019, 04:29:29 pm
I had one of the £10-15 ones that infest fleabay.  It worked for a while, then got increasingly stroppy I think due to poor battery contacts, which I couldn't molish.

Binned them in frustration and bought a set with a dial gauge to 0.01mm. Old tech, works perfectly.  This cheap Chinesium stuff made to a low price is crap.  No surprise there then, but I didn't want to pay £50 or more for something I used occasionally.  Having said that I use my dial gauge calipers several times a week.  They are perfect.
Title: Re: digital vernier callipers
Post by: T42 on May 20, 2019, 04:57:28 pm
No probs with mine, used a dozen times a day on some builds.
Title: Re: digital vernier callipers
Post by: canny colin on May 20, 2019, 09:15:44 pm
Thanks for all the replies , lots of food for thought colin
Title: Re: digital vernier callipers
Post by: gibbo on May 21, 2019, 07:52:12 am
I believe that you get what you pay for, mostly...

I have a few sets of Mitutoyo calipers with the oldest probably being almost 30 years old (OMG, I just worked that out) that I've used every working day of my life and I've never had an issue with them.

Quick search on eBay yielded this, which does seem to be quite cheap for Mitutoyo: https://www.ebay.co.uk/itm/Mitutoyo-Absolute-Digital-Digimatic-Vernier-Caliper-500-196-20-30-150-200-300mm-/253773449198

Regards,
Gibbo.
Title: Re: digital vernier callipers
Post by: Jurek on May 21, 2019, 08:38:15 am
I believe that you get what you pay for, mostly...

I have a few sets of Mitutoyo calipers with the oldest probably being almost 30 years old (OMG, I just worked that out) that I've used every working day of my life and I've never had an issue with them.

Quick search on eBay yielded this, which does seem to be quite cheap for Mitutoyo: https://www.ebay.co.uk/itm/Mitutoyo-Absolute-Digital-Digimatic-Vernier-Caliper-500-196-20-30-150-200-300mm-/253773449198

Regards,
Gibbo.

That does seem extraordinarily cheap, if they really are Mitutoyo. 
The Dengzhoushi, China location of the item has all of the red lights on the wall behind me flashing.
Title: Re: digital vernier callipers
Post by: canny colin on May 21, 2019, 08:48:16 am
 gibbo RE - Mitutoyo absolute digital vernier calipers .Chinese knock off lots of chat about them on engineering forums .  RRP for a 500-196-30  is £ 136.80 . Cheapest I can see from a reputable  uk dealer is £ 73.87. Best solution for a reasonably priced reliable "named "digital caliper off a uk dealer with back up and  a decent guarantee  I think, is the More & wright mw 110 -15dbl from machine dro off ebay for £ 26.47. still undecided if its worth the extra over a aldi / lidl or  ebay cheaper lnstruments   yours in confusion colin
Title: Re: digital vernier callipers
Post by: Brucey on May 21, 2019, 09:43:25 am
aldi ones have a (three year?) warranty.

cheers
Title: Re: digital vernier callipers
Post by: gibbo on May 21, 2019, 11:38:24 am
I believe that you get what you pay for, mostly...

I have a few sets of Mitutoyo calipers with the oldest probably being almost 30 years old (OMG, I just worked that out) that I've used every working day of my life and I've never had an issue with them.

Quick search on eBay yielded this, which does seem to be quite cheap for Mitutoyo: https://www.ebay.co.uk/itm/Mitutoyo-Absolute-Digital-Digimatic-Vernier-Caliper-500-196-20-30-150-200-300mm-/253773449198

Regards,
Gibbo.

That does seem extraordinarily cheap, if they really are Mitutoyo. 
The Dengzhoushi, China location of the item has all of the red lights on the wall behind me flashing.

Hmm, didn't look that closely at the location. Agree with your sentiment.

I have a non-digi Moore and Wright at home which I use quite frequently. It's good but of course you have to read the scales rather than a screen. These are obviously cheaper than the digi versions but they never run out of power!
Title: Re: digital vernier callipers
Post by: Valiant on May 23, 2019, 01:14:45 am
Happy with my 6 year old Lidls special, seems accurate compared to the super duper ones of engineering mates. If only it was a little stiffer.
Title: Re: digital vernier callipers
Post by: igauk on May 27, 2019, 12:01:39 am
I got some Moore & Wright ones off ebay last year like this: https://www.ebay.co.uk/i/254217866036?chn=ps (https://www.ebay.co.uk/i/254217866036?chn=ps). I'm sure they're pretty much the same as the other Chinese made versions but feel nicely machined, decent case, spare battery etc. and appear accurate enough for bike work.
Title: Re: digital vernier callipers
Post by: mattc on May 27, 2019, 09:47:30 am
Binned them in frustration and bought a set with a dial gauge to 0.01mm. Old tech, works perfectly.  This cheap Chinesium stuff made to a low price is crap.  No surprise there then, but I didn't want to pay £50 or more for something I used occasionally.  Having said that I use my dial gauge calipers several times a week.  They are perfect.
Being an old fart, I.m quiote ahppy using non-digital - what brand hve you got andy?

Can anyone else recommend an "affordable" good quality mechanical caliper?
Title: Re: digital vernier callipers
Post by: Ham on May 27, 2019, 10:15:51 am
...old fart...happy using non-digital

Really? then you are in the minority of old farts that can effectively use a vernier scale by eyesight, trouble free. Given the quality of even the cheap digital micrometers, it's hard to see the benefit, especially when the guaranteed lifetime of use for the mechanicals now has diminished value.
Title: Re: digital vernier callipers
Post by: Brucey on May 27, 2019, 11:37:33 am
I think he means the second sort

(http://www.wonkeedonkeetools.co.uk/media/wysiwyg/CM-Calipers-Micrometers-Katherine/CM-1-4.jpg)

All three are commonly referred to as 'Vernier calipers' even though strictly speaking only one of them is correctly described thusly.

cheers

Title: Re: digital vernier callipers
Post by: hubner on May 27, 2019, 11:51:53 am
I've got a few £5 Wilko mechanical vernier callipers but they don't seem to sell them anymore. And are accurate enough (certainly to 0.1mm) for musical instrument work which is my main use for them.

I prefer them because they don't need batteries, are reliable, are easier to read than dial calipers, and are simple with less bits to go wrong.
Title: Re: digital vernier callipers
Post by: mattc on May 27, 2019, 01:09:08 pm
I confess I've never seen a dial set in the flesh! They LOOK like they'd be a lot easier to read than "normal" verniers. I can imagine my eyesight quite soon struggling with such things.

I don't like stuff with batteries in if there's an equally good alternative. (Adding electronics is generally a wasteful exercise if they're not adding much benefit.)
Title: Re: digital vernier callipers
Post by: hatler on May 27, 2019, 01:58:09 pm
I've got a few £5 Wilko mechanical vernier callipers but they don't seem to sell them anymore. And are accurate enough (certainly to 0.1mm) for musical instrument work which is my main use for them.

I prefer them because they don't need batteries, reliable, are easier to read than dial calipers, and are simple with less bits to go wrong.
'Real' vernier callipers are exquisitely simple and ingenious, in equal measure, and they never go wrong.
Analogue dial callipers take a little longer to parse the reading, and there's a whole bunch of extra stuff in the way.
Electronic digital are always bloody flat when I need them. Why on earth complicate something so elegant with electronics ?
Title: Re: digital vernier callipers
Post by: Kim on May 27, 2019, 02:40:40 pm
Electronic digital are always bloody flat when I need them. Why on earth complicate something so elegant with electronics ?

Not had that problem with mine.  The only real advantage the electronic version gives you over a mechanical dial is that you can switch it to firkin/furlong/fortnight/farenheit units when necessary.

(Unless it's a high-end one with Bluetooth, which would presumably be useful if you're making large numbers of measurements to enter into a spreadsheet for quality control purposes, or something.)
Title: Re: digital vernier callipers
Post by: hatler on May 27, 2019, 02:59:27 pm
That's more an indication of how often I've used electronic callipers. But, when you need them, you need them, and if the battery's flat, they're NBU.
Title: Re: digital vernier callipers
Post by: Kim on May 27, 2019, 03:24:56 pm
TBH, if you've got this far into the 21st century, you've probably worked out how to manage batteries.  One more's hardly a big deal, given the shelf life of primary lithium cells.  Shame they don't use CR2032s like everything else, though.
Title: Re: digital vernier callipers
Post by: Jurek on May 27, 2019, 04:14:56 pm
Also, see my post upthread about how often I put mine back in the box when still switched on.
Title: Re: digital vernier callipers
Post by: mattc on May 27, 2019, 05:15:13 pm
Also, see my post upthread about how often I put mine back in the box when still switched on.
Exactly! I've had battery powered toys since before I was allowed a house-key - I don't seem to be getting any better at avoiding this particular form of human error  ::-)
Title: Re: digital vernier callipers
Post by: andytheflyer on May 27, 2019, 05:18:18 pm
Binned them in frustration and bought a set with a dial gauge to 0.01mm. Old tech, works perfectly.  This cheap Chinesium stuff made to a low price is crap.  No surprise there then, but I didn't want to pay £50 or more for something I used occasionally.  Having said that I use my dial gauge calipers several times a week.  They are perfect.
Being an old fart, I.m quiote ahppy using non-digital - what brand hve you got andy?

Can anyone else recommend an "affordable" good quality mechanical caliper?

These: https://www.ebay.co.uk/itm/RDGTOOLS-0-4-DIAL-VERNIER-CALIPER-MECHANIST-STEEL-SHOCK-PROOF-GEARING/370793223906?hash=item5654ff96e2:g:npkAAOSwXRxaw01G

Except mine are 150mm not 100mm, and metric not imperial - but it's the same supplier.  I'm very pleased with them.
Title: Re: digital vernier callipers
Post by: Jurek on May 27, 2019, 05:18:55 pm
Also, see my post upthread about how often I put mine back in the box when still switched on.
Exactly! I've had battery powered toys since before I was allowed a house-key - I don't seem to be getting any better at avoiding this particular form of human error  ::-)
A clear argument that you should return the house key to a responsible person, forthwith.
Title: Re: digital vernier callipers
Post by: mattc on May 27, 2019, 06:04:41 pm
thank-you both  :thumbsup:
Title: Re: digital vernier callipers
Post by: Brucey on May 27, 2019, 06:36:25 pm
FWIW the better electronic calipers (including the recent Aldi ones) have an auto-off feature so they don't run the battery down (which lasts longer anyway because the electronics have moved on too). They also hold the previous zero value when turned off. This is different from how such calipers used to be (which can do either or both); I occasionally use a friend's older Mitutoyo digital ones and they are not like the newer ones which is a source of irritation; to me because they don't hold the zero when turned off and to him because (he says) 50% of the time I put them back in the box without turning them off first..ahem... ::-)

Digital calipers are much easier on ageing eyeballs than any other sort and being able to zero the calipers and take easy negative readings, easy readings that would otherwise be several turns of a twirly dial , easy readings in metric or imperial etc are features that are not to be sniffed at.

FWIW I speak as someone who has almost zero tolerance of pointless battery powered gadgets; it is a very long time since I have felt it at all worthwhile to have anything attached to my bike that is powered by batteries.....  but even so digital calipers are one area where the advantages outweigh the shortcomings.

For example I have figured out a way of using such calipers for measuring chain wear (without the measurement  being influenced by roller wear) and it simply wouldn't be anything like as easy or even practical with non-digital calipers.

cheers
Title: Re: digital vernier callipers
Post by: Wobbly John on May 27, 2019, 07:52:29 pm
If you search t'internet, many digital calipers do not switch off completely, but can be adapted to do so...  ;)
Title: Re: digital vernier callipers
Post by: TheLurker on May 27, 2019, 08:01:31 pm
Quote from: mattc
Can anyone else recommend an "affordable" good quality mechanical caliper?

For fine work I use one of these...

- https://www.drapertools.com/product/50605/Expert-0-140mm-Vernier-Caliper-with-Fine-Adjustment

For quick and dirty I use one of these...

- https://www.drapertools.com/category-products/4900/Vernier-Calipers

... and it's also convenient for sticking in a pocket checking balsa in the increasingly rare "proper" model shops and for taking rough measurements off stick and tissue models without bashing them to bits.

Draper seem to have a goodish range of both electronic and mechanical in the 30 quid price range.

https://www.drapertools.com/category-products/4900/Vernier-Calipers
Title: Re: digital vernier callipers
Post by: pcolbeck on May 27, 2019, 09:54:33 pm
Wiha do a dial caliper that is glass reinforced plastic rather than metal for a reasonable price:

https://uk.rs-online.com/web/p/calipers/4982013/

Could be useful if you dont want to mark stuff like a steel one might. I don't own one but Wiha kit is usually top quality.
Title: Re: digital vernier callipers
Post by: Tim Hall on May 28, 2019, 08:08:00 pm

For example I have figured out a way of using such calipers for measuring chain wear (without the measurement  being influenced by roller wear) and it simply wouldn't be anything like as easy or even practical with non-digital calipers.

cheers
Now that sounds interesting. Care to share?
Title: Re: digital vernier callipers
Post by: Brucey on May 28, 2019, 10:13:46 pm

For example I have figured out a way of using such calipers for measuring chain wear (without the measurement  being influenced by roller wear) and it simply wouldn't be anything like as easy or even practical with non-digital calipers.

cheers
Now that sounds interesting. Care to share?

see https://forum.cyclinguk.org/viewtopic.php?f=5&t=115336 (https://forum.cyclinguk.org/viewtopic.php?f=5&t=115336)

cheers
Title: Re: digital vernier callipers
Post by: Tim Hall on May 28, 2019, 10:23:00 pm

For example I have figured out a way of using such calipers for measuring chain wear (without the measurement  being influenced by roller wear) and it simply wouldn't be anything like as easy or even practical with non-digital calipers.

cheers
Now that sounds interesting. Care to share?

see https://forum.cyclinguk.org/viewtopic.php?f=5&t=115336 (https://forum.cyclinguk.org/viewtopic.php?f=5&t=115336)

cheers
Nice. Elegant. Thanks.
Title: Re: digital vernier callipers
Post by: Brucey on May 29, 2019, 08:24:12 am
rare event; went into halfords yesterday... I found out three things

1) they have revised their tool range and they appear not to sell their ratchet spanners individually any more. Presumably they will have to break a set up to fulfil warranty claims...?

2) they don't stock 'finish line' lubes

3) they have for £19.99 a 'laser' branded digital caliper.  However the caliper is (all?) plastic and is supplied in a blister pack i.e. without a case I think.

I worry about plastic caliper jaws wearing out of spec and giving erratic readings sooner than they should. But the halfords caliper might fit the bill for "a sunday afternoon distress purchase" I suppose.

cheers
Title: Re: digital vernier callipers
Post by: pcolbeck on June 03, 2019, 06:33:31 pm
Here is a good video showing the workings of a dial gauge:

https://youtu.be/e5i0r0-dd7I

Title: Re: digital vernier callipers
Post by: Plug1n on June 06, 2019, 02:40:55 pm
Received some Mitutoyo digital calipers today from the Amazon link upthread.

I had been lusting after these for some time and they complement the Mitutoyo interior dial calipers that I picked up in Tokyo maybe 30 years ago.  This all for checking dimensions of clarinets rather than cycling gear.

I have a pair of Aldi/Lidl digital calipers that are pretty good for the price but the battery quickly goes flat if I leave it in.

The Mitutoyo is lovely to hold and fondle......
Title: Re: digital vernier callipers
Post by: T42 on July 24, 2019, 01:57:40 pm
My no-name digital just gave up the ghost - display all to cock and buttons ineffective.
Title: Re: digital vernier callipers
Post by: Brucey on July 24, 2019, 02:29:13 pm
did it get damp?

FWIW if you suspect damp (even sweat can do it), wipe down the outside with WD40, dry it out, leave it without a battery inside for a few hours at least, and try again, preferably with a new battery.

Sometimes they get their digital knickers in a digital twist and then come back to life after a period of time without a battery in. If the buttons don't work persistently it may mean that the insides of the caliper have become contaminated. Like TV remotes, if the thing is dismantled and the  buttons are cleaned, often this restores function.

cheers
Title: Re: digital vernier callipers
Post by: Randy_Butternubs on July 25, 2019, 10:13:31 am
AVE did a good video on cheap digital calipers: https://www.youtube.com/watch?v=KnDype-j3hk

Upshot: Cheap calipers can be perfectly accurate (especially for bike use) but they never really switch off, even when the display is off, so the batteries run flat even when unused. They also don't have brownout protection\a low battery warning and when the batteries start to run down they give erroneous readings.

Solution: store them with the batteries out or buy a bunch of cheap coin cells off the internet in preparation. Keep something of known dimensions around to test if you are getting suspect readings.

His findings mesh with my observations. I have several sets of calipers, cheap and expensive, and they are all accurate enough. Everyone I know with (cheap) digital calipers finds they eat batteries.

Re: dial calipers:
I bough some nice Starrett ones a while ago but I don't like them. In use the dial isn't as easy to mentally parse as I expected and the whole-millimeter reading is not as clear as it could be. The incredibly fine rack and pinion mechanism needs only the tiniest just-visible speck of sawdust to skip.

Dial calipers lack the useful features (zeroing, units etc) and easy readability of digital ones. Vernier calipers are simpler and are easier to read once you are used to them in my opinion.
Title: Re: digital vernier callipers
Post by: T42 on July 25, 2019, 12:47:44 pm
@Brucey: It didn't get damp that I know of, it lives on a bench that is woodwork-only. There's a freebie digital calc beside it that has been in the workshop for 30 years, no problem.   Bike stuff is 3 or 4 metres away.

I'll take the batteries out and let it sit for a while - I have a good-quality trad one and I'm told that mental exercise is good for the brain.

@Randy: AVE has a turn of phrase, doesn't he?

I checked my battery and it's down from 1.5v to 1.0, which should still be functional.  It looks as if the display contacts are fuxxorzed.

I forget who made my steam calipers, they date from ~1995 - probably German. Got a nice wooden box somewhere. They're very clear.
Title: Re: digital vernier callipers
Post by: Kim on July 25, 2019, 12:51:29 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.
Title: Re: digital vernier callipers
Post by: pcolbeck 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.
Title: Re: digital vernier callipers
Post by: T42 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.
Title: Re: digital vernier callipers
Post by: Brucey 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
Title: Re: digital vernier callipers
Post by: hubner 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.
Title: Re: digital vernier callipers
Post by: T42 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.
Title: Re: digital vernier callipers
Post by: T42 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.
Title: Re: digital vernier callipers
Post by: Ham 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
Title: Re: digital vernier callipers
Post by: Brucey 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
Title: Re: digital vernier callipers
Post by: T42 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.
Title: Re: digital vernier callipers
Post by: Feanor 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.
Title: Re: digital vernier callipers
Post by: TheLurker 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.
Title: Re: digital vernier callipers
Post by: Kim 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.
Title: Re: digital vernier callipers
Post by: Randy_Butternubs 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.
Title: Re: digital vernier callipers
Post by: Kim 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.
Title: Re: digital vernier callipers
Post by: Vince 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.
Title: Re: digital vernier callipers
Post by: Randy_Butternubs 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.
Title: Re: digital vernier callipers
Post by: Randy_Butternubs 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  ;)
Title: Re: digital vernier callipers
Post by: T42 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).