Hi Robin,

The scale is capacitive. Most cases of varying readings I have seen can be resolved by cleaning the scale carefully with meths or changing the battery.

Zero readings can drift overnight on the calipers, but I haven't found this with DROs. The heads are identical, so I think it may be something to do with leaving calipers closed when the temperature cycles overnight? It is also possible to tap the zero button when closing the caliper if I'm a little careless.

For the price I consider them disposable, but I've never had to throw one out and some of mine are well over twelve years old old.

It's worth making sure you don't have the real cheapies – go for stainless steel reading to 0.0005"/0.01mm and loom for the thumbscrew at the top for adjusting the gib.

If you have a duff one, try again, I have five or six calipers (including a couple of plastic 'hacks&#39 and three DROs, only one (a DRO on the mill) has totally failed (I got a new read head for very little from Machine DRO). I remember using my vernier caliper once, but it was a long time ago.

Neil

Hi Robin

This applies to all of us not just Myfordians; As you say to have a decent readout you have to 'pays your money' i.e. Mitutoyo, all these digi callipers are made for the mass market in PRC & sold under many brand names inc. Starret, M&W etc. I have a 8" Mitutoyo digi vernier, & 0 – 25 mic that I use as masters, I use a 3" & 4" digi verniers for general use ( from Machine-DRO UK, usual disc. ) again made in PRC, but I also have a couple of 'older' analogue mic's inc. one I bought when I served my apprenticeship so its over 45 yrs old, & still accurate, some of which I use to double check a final reading on stuff I am doing ( not a lot lately ) .

What I find is that for consistent readings I leave my mic's / verniers to 'acclimatise' to my workshop temperature once I have had the heaters on for about an hr, or I have a vernier in my top pocket where it reaches body temp so as I use it it maintains repeatability, & yes I still check 'zero' occasionally. The trouble with batteries is that when cold they tend to have a voltage drop until warmed up so keep them at a constant temp if you can.

George.

Digicals are all the rage now. Half the people at work cant even read a mic.

I have many on my calibration system and I wouldnt trust them to within a thou let alone 0,01mm. The cheap ones certainly do "drift" very easily. Most of the time the cause is swarf or dirt on the tracks and they all need regular cleaning with meths to flush out the tracks. Even a tiny amount can throw the reading out of accuracy (not just at zero either) and the cheaper the caliper = the more sensetive to it they are. It is a case of you get what you pay for here and Mitutoyo make by a long way the best and most reliable. Not totally proofed againt drift but much much better. Someone here recently bought a cheap one from SPI and it couldnt even hold a zero out the box. I flushed that and it was dirty from manufacture. Even after that it wasnt great and is now marked with a 'do not use'.

I use mics or verniers and dont trust them in general, much prefer my eye. Buy a Mitutoyo. They are worth the money.

Am I being cynical to think that having to clean digital calipers carefully is a 'design flaw' but when it come to the rack type, it's 'good care'?

Neil

Regardless of whether the label says Mutitoyo or Xmas Cracker, I habitually check the zero reading before and after critical measurements and periodically check a known reference piece. This will certainly show up any significant inconsistencies, without needing any fancy calibration equipment. My generic digital calipers seem to be pretty reliable but there again, if they hadn't been, I would have kept looking until I found some that were.

When I took one of my glass DRO scales apart to shorten it, I found nice finger prints all over it from when it was manufactured – obviously I took the opportunity to clean it, although it hadn't been causing a problem. They need to be able to tolerate a certain amount of contamination but like any tool you depend on it pays to periodically clean, check and inspect them.

Murray

My cheapo cross slide vernier DRO has been fine for a year or two so far, one battery change to date

Just got a 12inch one for the lathe bed, 22quid

I reckon that the location where I mount it will be the most critical factor in it's longevity and usefulness

I've got several cheap ones in the shop in case I drop them. None of them are anywhere near as good as the Mitutoyo ones that stay warm and dry in doors!

I have a cheapo digital caliper (from Lidl IIRC) which in recent weeks would, without warning, change reading by 5.08mm (always this amount). This has not happened since renewing the battery.

Trevor

Two tenths of an inch

I did an experiment with my usual caliper – not Mitutoyo, it's Proops, circa 2000

Left set at 0.01 on the bench for several hours, it crept up to 0.01mm.

I then opened and closed it as fast as I could (as in literally snapping it closed). i could not get an error.

Put it on a windowsill about 5" above a heater, left it there for about two hours until it was very warm. To my surprise it read 0.10mm, quite a change!. It's back on the bench now, and in the time it's taken me to type this the display has dropped to 0.08mm.

<Interruption while one of the lads comes in and says 'have you ever heard of a band called 'Wishbone Ash'?>

It's flickering between 0.06 and 0.05mm now.

I just tested it on a 25mm test bar, and it reads 25.05mm.

My immediate conclusion is that these cheap units are highly temperature sensitive but that the error is a zero error, so that the issue is keeping them at the same temperature your zeroed them at.

Neil

P.S. it's flicking between 0.04 and 0.03 now, and doesn't feel warm anymore.

It's only a fair test and criticism if you repeat the experiment with your mitutoyo's. Of course if they creep….