My digital calipersseems to give varying readings

[I.M. OUTAHEREParticipant @i-m-outahere]

The consensus from my clock experts and many here is that the way to go for precise work is the micrometer and this probably means a good brand

True but even a cheap set of digital callipers have many uses in the workshop , You can speed up your job by using the callipers to check your work until you get close to the finished dimension then switch over to a micrometer for final sizing -don’t forget to let the part cool down if the dimension is really critical ! This also means your good tools stay safely tucked away from harm until you really need them which will increase their longevity .

If you are going to buy precision measuring tools then buy known brands and i would recommend you buy from a certified retailer as Chinese knock offs are prolific on places like Ebay and are usually marketed as new old stock , you also need to be careful buying used items off those sites as well .

[SillyOldDufferModerator @sillyoldduffer]

Posted by Christopher judd on 14/08/2019 19:46:33:

… The consensus from my clock experts and many here is that the way to go for precise work is the micrometer and this probably means a good brand. A cheaper brand made with softer steel or poor tolerances would not be reliable. …

Chris

Fellow hobbyists often believe expensive tools to be essential to success and there's often a hint the older the tool the better, modern rubbish is no good etc. I disagree. Tools should be matched to the requirement, not bought on recommendation. This is important if you are on a budget because the money might well be spent more effectively on something more useful. As most hobbyists don't work to absolute dimensions, they don't need precision equipment.

How can stuff be made without accurate measuring tools? It's quite easy; a divider, caliper, micrometer, gauge, jig, or another part can all be used as comparators. Fit is achieved by matching parts rather than making them individually to precise dimensions.

Although a digital caliper and micrometer speed work up, it's possible to manage without having them at all. The old guys produced tasty clocks well before high-tech measuring was invented. The marine chronometer was invented before the micrometer.

I manage OK with a cheapo micrometer from MachineMart. Although the locking-lever fell off and had to be repaired by me, it's accuracy is good.

Dave

 

Edited By SillyOldDuffer on 15/08/2019 08:23:45

[roy entwistleParticipant @royentwistle24699]

Dave I was taught as an apprentice never to use the ratchet on a micrometer. You develop a feel for it, as you develop a feel for proper calipers and verniers

Roy

[Mick B1Participant @mickb1]

Posted by SillyOldDuffer on 14/08/2019 19:22:55:

As nobody's mentioned technique yet, I'll mention it takes practice to get accuracy out of calipers. Straightforward enough to get to within 0.05mm with a digital caliper but care is needed to exceed that.

…

Dave

I think that's true too. Using the thumbrest or wheel in a caliper closes the sliding jaw with the force on the beam end, and any rock at all in the fit could cause tilt in the jaw and *potentially* affect the reading. Bringing the jaws together for a zero reading will create a self-paralleling effect that isn't there when you're measuring a diameter or local feature of the workpiece.

Although I couldn't swear I've definitely noticed such a difference, I make it a habit when possible, and especially when measuring a workpiece still in the machine, to pinch the caliper jaws together with thumb and forefinger as near as possible the critical point of measuring, rather than using the wheel.

Now, maybe the stuff I do is coarse compared to what some on here claim, but I don't think I've ever been misled by a digital caliper reading, allowing for its displayed resolution. I only tend to resort to the mic when I'm chasing tenths, which is not very often.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Christopher judd on 14/08/2019 19:46:33:

[ … ] The consensus from my clock experts and many here is that the way to go for precise work is the micrometer and this probably means a good brand. [ … ]

.

With all due respect to your experts: Please pause for a moment to consider the clock and watchmaking work that was being done in the early days.

Unless you are planning to start mass-production of interchangeable spares; most of your horological work will require 'fitting' rather than 'making to size'. … Yes, of course, a decent micrometer is a useful thing to have; but the ability to make a part which properly fits another is paramount.

Many of the old books are available on archive.org

MichaelG.

.

Edit: just realised that Dave has already made this point 

Edited By Michael Gilligan on 15/08/2019 09:45:02

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 15/08/2019 09:41:43:

[ … ]

Please pause for a moment to consider the clock and watchmaking work that was being done in the early days.

[ … ]

Many of the old books are available on archive.org

.

This is a very good place to start: **LINK**

https://archive.org/details/watchmakershand00tripgoog/page/n4

MichaelG.

[Alistair Robertson 1Participant @alistairrobertson1]

I bought a couple of digital verniers from Aldi a couple of years ago. One works perfectly but the other gains 0.200" when I move it in and out, Eventually it goes up to a reading of 9.999" if I persevere.

I took it back to the store but they were sold out and the manager was not prepared to send them back as she said they were working as they should!! I contacted Aldi at the number on the paperwork but they weren't helpful at all and said I had to return them to the store. I tried again but with no luck at getting them to understand the problem and they said they were a special buy and they wouldn't be getting any more. At this point I gave up and as they only cost about £8 it really wasn't worth he hassle. They are still somewhere in my workshop.

[Steve CrowParticipant @stevecrow46066]

If you are going down the horological route, you are probably going to have to make a few tools.

Get yourself a good micrometer. A Mitutoyo 103-137, the entry level model, can be had new for under £50 and will last you forever. Practice using it on known diameters until you get a feel for it. I was taught as an apprentice but I'm sure there are guides on the internet.

Calipers can get in places micrometers can't. They can also measure internal and depth measurements. Technique plays a big part in getting consistent measurements. I use the same method as Mick mentions above.

Cheap digital calipers are hit and miss. About 6 years ago I bought the cheapest one I could find on ebay for rough work. It still works fine with accurate and consistent readings and it doesn't eat batteries. Maybe I was just lucky.

[mechman48Participant @mechman48]

Posted by roy entwistle on 15/08/2019 08:44:53:

Dave I was taught as an apprentice never to use the ratchet on a micrometer. You develop a feel for it, as you develop a feel for proper calipers and verniers

Roy

SNAP! me too, satisfying when you got to know the 'drag' on a micrometer, & the jaws on callipers. All good stuff.

George.

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