Vernier Caliper - cheap!

[samjmann]

Aldi are selling a digital caliper for £8.99. For DIY use it seems OK. Comes with a spare battery, case and a 3yr warranty. It's in the so called centre Isle stock!

SJM.

[ex 2 Base]

I have a Mitutoyo digital caliper and an Aldi one which is about 5 years old, both are in regular use and i can't find one more accurate than the other. Actually the display on the Aldi is much clearer than the Mitutoyo. The Mitutoyo cost £80 15/20 years ago and the Aldi £6 or£7. Ted

[fetteler]

The difference won't be in the accuracy it is in the fact that your Mitutoyo caliper is 20 years old and still working properly

Steve.

[Station X]

I had a cheap digital vernier caliper bought from Maplin which was excellent until I dropped it! I bought two more of the same design and they were useless refusing to zero at the same point on successive closures. Probably perfectly good for vintage radio work measuring screw sizes, shaft diameters etc.

I then bought a Mitutoyo which I can't fault.

[Bazz4CQJ]

I bought one from Lidl about a year ago, which may well be the same. Some advice I found on a another forum was to give it a really good clean, and sure enough, there was a lot of what I think were particles of grindstone trapped inside. Took a few minutes to get it all out, but the action was much improved.

B

[fetteler]

Originally Posted by Station X

I had a cheap digital vernier caliper bought from Maplin which was excellent until I dropped it! I bought two more of the same design and they were useless refusing to zero at the same point on successive closures. Probably perfectly good for vintage radio work measuring screw sizes, shaft diameters etc.

I then bought a Mitutoyo which I can't fault.

My point exactly. I too have a Mitutoyo, I also have a cheap set for rough and tumble use. The cheap ones last a few years but then start playing up. Horses for courses.

Steve.

[David G4EBT]

The callipers may be cheap, but they're not cheap tat.

There have been threads and discussions about the merits or otherwise of cheap callipers over the years and it might be worth highlighting again, the importance of using 1.55V silver oxide cells - not 1.5V alkaline ones. People often complain of the short battery life and malfunction of the digits of cheap digital callipers, but (apart from dirt in the sensor head), the most likely cause is using the wrong LR44 cells. (alkaline instead of silver oxide). The same issue will arise with expensive callipers. I guess that the callipers are so evidently simple to use that few of us bother to refer to the instructions, so when batteries are needed, head straight for Poundland. Big mistake.

I've got three digital callipers of various makes - all of them budget types.

Thee oldest pair I bought were from a discount shop ('Kijkshop') in Breda, Holland, in 1999. They're still used several times a week and are doing fine. Another is a Machine Mart ('Clarke' brand), and a third one was from Aldi, maybe five years ago. They all work fine and the readings compare very closely. The instructions state that the battery must be a 1.55V silver oxide battery - the ones that the likes of Poundland et al sell are Alkaline, with an initial Voltage of 1.5V, probably have a lower capacity and certainly an inferior discharge curve as compared to silver oxide. If the voltage falls below 1.45V in use, (which I dare say won't take long), the callipers will malfunction, usually flashing continuously.

I've only got one set of instructions (for a Clarke Brand/Machine Mart instrument) and here's what they state:

Quote:

8-<

Power Source: One silver oxide 1.55V LR44, capacity 180 mAh. Current <20uA

'Troubleshooting': Digits flash randomly or all five digits flash simultaneously: Battery Voltage below 1.45V.

Unquote.

8-<


When I bought the callipers, in all three sets, the LR44 silver oxide cell was stored in the little round hole in the foam till fitted. I keep a spare one in the hole in each one for when needed. The only problems I've had with one of the callipers is that I use it when I'm woodturning and fine dust to can get drawn into the slide, so I have to remove the slide assembly and clean it with a sable artists brush from time to time. To remove the assembly, there are two tiny grub screws, one either side of the locking screw on the top side of the slide.

Of my three callipers only the Clarke one has an on/off switch - the other two auto switch off when left alone for a few seconds, so I suspect that they go into 'sleep mode' and draw a minute current till next operated, because they 'wake up' the second that the slider is moved. (It would take a long time to reduce the battery Voltage of a 180mAh silver oxide cell from 1.55V to 1.45V at only <20µA).

I’ve attached two data sheets which show the difference in capacity and discharge curves for alkaline and silver oxide cells which might be of interest.

I have never had a problem with plain LR44's, OK they do go flat eventually but are so cheap by the dozen I keep a good stock.

[bigfathairyvika]

Just looking at the darasheets, would it matter that discharge curve for the silver oxide is at less than a 1/4 of the current of the alkaline.
Other than that, I can see that the voltage drop of the alkaline is seriously more than the silver oxide.

I bought my Mitutoyo calipers nearly 30 years ago and they are still perfect. Only changed the battery twice.

[mark_in_manc]

I find expensive ones are coolant proof, cheap ones not - but not many electronics workshops have cutting fluid flying around!

[G6Tanuki]

May be cheap, but do they come with any sort of credibly-traceable calibration?

I remember a friend used some calipers-of-unknown-provenance to measure the journals on an engine he was rebuilding, and ordered bearings on the basis of what-he-read.

When fitted, the engine could not be rotated.

His calipers turned out to be reading 25 thou oversize!

[Bazz4CQJ]

Originally Posted by G6Tanuki

May be cheap, but do they come with any sort of credibly-traceable calibration?

Absolutely not, but neither do inexpensive DVM's, which are often impressively accurate. People should know to do at least some initial checks on budget price kit.

As for accuracy, the definition of "Quality" that I was brought up with is "adequacy for purpose", and for many of us, the £10 verniers are adequate.

B

[fetteler]

Yes, and on the basis of that definition you have to say that nine quid for some digital calipers is a good buy: if you haven't got any and want/need some then what are you waiting for?

Steve.

[wireman]

the specifications don't claim any accuracy which is a bit annoying. Does look like a bargain and for a stainless model as well.

[samjmann]

Thanks for all the replies everyone.

The batteries supplied with this one are LR44, but no mention of being silver oxide or alkaline. For me, I'll only use this occasionally and then on things where absolute accuracy won't be required.

I suppose it's the same as buying a budget soldering iron, compared to having a Pace/Metcal/Weller etc. It's down to long term use, spare parts availability and durability and the demands made on the product.

What did surprise me is that there is a slip inside the case to return the unit to a service company in Germany (Sertronics) during the 3yr warranty period!!

SJM.

[duncanlowe]

Interesting about batteries. I have two cheap ones, different brands. I use the same batteries in both. They don't get daily or weekly use, perhaps monthly. But one of the two almost always has a low battery problem when I come to use it though the other does not.

[fetteler]

Originally Posted by wireman

the specifications don't claim any accuracy which is a bit annoying. Does look like a bargain and for a stainless model as well.

Have you ever seen a set of calipers which were not stainless?
I certainly haven't!

Steve.

[Herald1360]

Yes. Back in the '80s I was given a freebie blue plastic caliper by a component supplier's rep. It survived for years in my toolbox. You could read it to about a quarter of a millimetre which was good enough for most requirements in an electronics lab.

[Refugee]

I have found that calipers use a very small amount of power from the battery all the time.
I use the 1.5 volt pound shop batteries but remove them when the caliper is not in use.
I find that the battery recovers enough terminal voltage over several weeks that I get enough time to measure up an electric motor bearing before the voltage drops.
With pound shop batteries I can afford to put a new one in each time I use the caliper as it is perhaps only monthly. With all batteries the bistable that switches the caliper on and off still slowly uses the battery up to hold it in the off state. At the end of the day the hold off current has to be above the static on clothing people are wearing as they walk past the bench the caliper is laying on when not in use.

My advice is use an expensive battery if the caliper is used more than two or three times per day and remove it at weekends. It is not worth removing the battery that many times in one day in a work place.
For occasional home use always take the battery out when not in use and it will work out cheaper with pound shop batteries even though you only get 10% of there capacity.

[Electronpusher0]

I bought one on SJM's recomendation, I already have a mitutoyo non digital vernier caliper and a digital micrometer but thought this would be handy for quick check use.
I will try giving it a clean as it seems a bit rough right on the zero point, also the plastic scale is coming unstuck.

While I was in there I also spotted a set of 8 long reach screwdirivers, I grabbed them as well.

Peter