Calipers – Dial v digital

[Brian GParticipant @briang]

Posted by Phil H1 on 26/10/2017 12:34:46:

Does anybody know where to get a small (less than 6" traditional vernier i.e., without the battery or the dial?

I bought a not so cheap digital version a few years ago and it went into the bin quite quickly – completely unreliable. I have exactly the same issue as Duncan i.e., trying to access a component under a milling machine.

My 40 year old Rabone and Chesterman is still going strong but it is just a little bit too long.

Phil H

Oxford and Kennedy both do 5" mm/thou vernier calipers but things seem to get weirder as they get smaller.

Axminster list a 100mm Vernier caliper. Unfortunately, like their 100mm steel rule, it is metric only How much money does it actually save them to give it only one scale? **LINK** M&Ws 70mm caliper similarly is metric only. **LINK**

Farnell list a Hitec 100mm caliper, but the imperial side is in 1/128" – I'm not sure I could cope with that! **LINK**

Brian

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Neil Wyatt on 26/10/2017 08:03:35:The ones that go dodgy generally need the scale cleaned with meths and a new battery.

If that fails it only takes a few minutes to dismantle the reading head and clean the PCB that slides on the scale. Small bits of swarf can get trapped between the tracks. I find a fibreglass pen brush ideal for such jobs.

Russell

[ChrisHParticipant @chrish]

Well, I checked the battery, almost full, adjusted the positive battery contact so it pushed harder against the battery, cleaned the bar with meths (or rather the French equivalent which doesn't have the blue dye in it) and adjusted the two 'gib strip' type wee screws on the top so it slides smoothly with next to no play.

Cheapo must have heard me threatening it with the bin because it's now behaving itself again, but I think I will take Peter's advice in time and get a good dial caliper too.

Peter makes a good point as to the accuracy of the digital calipers in general, I have noticed that there is often a wee bit of variance there compared to the reading on the mic and I tend to believe what the mic is telling me first, especially as whenever the zero is checked on the digital it is often 0.0005-0.001" out after a slide or two up and down the scale. But it was a cheapo!

Chris

[Howard LewisParticipant @howardlewis46836]

+1 for cleaning a misbehaving digital calliper. Sometrimes just wiping the scale with a clean cloth will suffice, at worst a deeper strip down and wip;e has always sufficed. Mine is years old, from Lidl, and gets used more than either the M & W digital, or the Mitutoyo dial one. Resaon? Sheer idleness on my part.

But if it ain't broke, don't fix it!

Howard

[Neil WyattModerator @neilwyatt]

Adjusting the gibs (all but the cheapest have a gib) can help with inconsistent zeroing.

> meths (or rather the French equivalent which doesn't have the blue dye in it)

Eau de vie?

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Neil Wyatt on 26/10/2017 18:34:50:

Adjusting the gibs (all but the cheapest have a gib) can help with inconsistent zeroing.

> meths (or rather the French equivalent which doesn't have the blue dye in it)

Eau de vie?

Alcool à brûler from any supermarket in France. Keep the eau de vie for drinking

Russell

[ChrisHParticipant @chrish]

Non – c'est "Alcool à brûler".

Cheap as chips in most French supermarkets, about 7-8 euros for 5 litres, the winos over there can buy reasonable supermarket plonk for about 2 euros a bottle so presumably there is no need to make it unpleasant and dyed so winos won't drink it, not like over here!

Chris

Russel beat me to it!

Edited By ChrisH on 26/10/2017 19:05:25

[Neil WyattModerator @neilwyatt]

Posted by Neil Wyatt on 26/10/2017 18:34:50:

Adjusting the gibs (all but the cheapest have a gib) can help with inconsistent zeroing.

> meths (or rather the French equivalent which doesn't have the blue dye in it)

Eau de vie?

Il semblait que 'ceci n'est pas une blague…'

[Anonymous]

My answer to the original question would be neither. I prefer to use micrometers, external, and internal, where possible. I have two vernier calipers, a 150mm Mitutoyo and a 600mm Fowler. As an aside neither will actually measure the headline number. I use the Mitutoyo mostly for quick measurement of parts when I am creating 3D CAD models. The Fowler gets used for larger parts, over 450mm where my micrometers run out, and a tape measure doesn't quite cut it. It might be a personal thing, but I don't find vernier calipers particularly easy to use. It is difficult to ensure that readings are taken perpendicular, especial for hole measurement.

Andrew

[ChrisHParticipant @chrish]

Neil – quite!

Andrew – I agree, much prefer to use micrometers myself, maybe it is an age thing (I was taught on micrometers in imperial not calipers in metric) but I also seem to find them more accurate, and always use them when I am chasing thous in preference to calipers; calipers just get used in the sequence tape measure – steel rule – calipers – micrometers as I get to final size, but thats just my way of working.

Chris

[SillyOldDufferModerator @sillyoldduffer]

Posted by ChrisH on 27/10/2017 11:17:29:

… much prefer to use micrometers myself, maybe it is an age thing… but I also seem to find them more accurate …

Chris

Not an age or metric thing. It's because micrometers are more accurate than calipers. They feature:

• A simple reliable working principle
• A highly accurate ground thread
• A stiff U frame that's difficult to bend whilst taking measurements
• Heat proof pads on the frame to minimise temperature changes due to handling. (Usually)
• A ratchet/torque mechanism to ensure that the user applies the right pressure
• Flat anvils that are easier to keep straight on the object being measured than knife jaws

The downside is that micrometers are far more specialised than a caliper, not a direct alternative. Although calipers are inherently less accurate than a micrometer, they can be used for a wider range of measuring tasks. A caliper can measure inside and outside diameters, and depths, and it does so over greater distances than a micrometer. The price paid for the caliper's extra utility is reduced accuracy. As you say, tape/rule/caliper/micrometer. Exactly right. Each has it's place and limitations. Buy all of 'em!

Dave

[Neil WyattModerator @neilwyatt]

Micrometer comes into its own when you a making something to fit a precision part blind.

If I want a shaft to be a tight fit in a hole, I use the hole as a gauge if at all possible, and a vernier is good enough for creeping up on size. This especially true if I made the hole, as even using bore gauges or my bore micrometer I am not 100% confident of measuring the size spot on.

Neil

Edited By Neil Wyatt on 27/10/2017 16:49:45

[Anonymous]

Posted by SillyOldDuffer on 27/10/2017 12:23:25:

The downside is that micrometers are far more specialised than a caliper, not a direct alternative. Although calipers are inherently less accurate than a micrometer, they can be used for a wider range of measuring tasks. A caliper can measure inside and outside diameters, and depths, and it does so over greater distances than a micrometer.

Ah yes, but I've also got a depth micrometer covering 1" to 12" and internal micrometers from 1" to 32". The internal micrometers are not easy to use, but easier than calipers. You can never have too many micrometers; get with the groove (micrometer).

For hole/shaft combinations I usually make the parts separately, sometimes weeks or months apart, and expect them to fit together. Shafts are checked with a micrometer, and for holes I grind a plug gauge, where it is easy to tweak the odd tenth or two.

Andrew

[Phil H1Participant @philh196021]

Not an age or metric thing. It's because micrometers are more accurate than calipers. They feature:

• A simple reliable working principle
• A highly accurate ground thread
• A stiff U frame that's difficult to bend whilst taking measurements
• Heat proof pads on the frame to minimise temperature changes due to handling. (Usually)
• A ratchet/torque mechanism to ensure that the user applies the right pressure
• Flat anvils that are easier to keep straight on the object being measured than knife jaws

Dave,

I was always taught (by more than one) to avoid using the ratchet/ torque mechanism on a micrometer because it was unreliable. In addition, it is very difficult to hold the micrometer properly and use the ratchet.

Phil H

[thaiguzziParticipant @thaiguzzi]

Dial or digital – neither.

Quality vernier calipers. As long as your eyesight is still half decent….

[IanTParticipant @iant]

Whereas I was told to always use the ratchet to ensure a repeatable torque….and I do so without any problems in use… but each to their own…

Regards,

IanT

[ChrisHParticipant @chrish]

Andrew – I like you method of working, very sound, but not all – perhaps very few, I don't know – of us have the grinding facilities to accurately grind hole plug gauges parallel and to size, we have to make do with the measuring tools we have, but as you say, you can't have too many micrometers, inside and out! I need a depth one now too.

thaiguzzi – quality verniers are very good but the problem using them you have identified, eyesight. That doesn't get any better as you get older and a lot of us here are not so young as we like to think! (Think mind making promises the body can't keep anymore. You think you are still 27 but the reality is more like 72!). That is why digital and to a slightly lesser extent dial calipers have their attraction, big figures easy to read.

Chris

[Anonymous]

A ground gauge isn't always needed. For my traction engine rear wheel hubs I simply used a piece of the stock bar I bought for the axles.

All my micrometers have either been inherited, or bought on Ebay. I've only had one complete duffer, a 4"-5" that was about 15 thou out, ie, the frame was sprung. I put it back on Ebay with a note saying it was in error; and it still sold!

Andrew

[SillyOldDufferModerator @sillyoldduffer]

Posted by Phil H1 on 27/10/2017 22:43:06:

Not an age or metric thing. It's because micrometers are more accurate than calipers. They feature:

• A simple reliable working principle
• A highly accurate ground thread
• A stiff U frame that's difficult to bend whilst taking measurements
• Heat proof pads on the frame to minimise temperature changes due to handling. (Usually)
• A ratchet/torque mechanism to ensure that the user applies the right pressure
• Flat anvils that are easier to keep straight on the object being measured than knife jaws

 

Dave,

I was always taught (by more than one) to avoid using the ratchet/ torque mechanism on a micrometer because it was unreliable. In addition, it is very difficult to hold the micrometer properly and use the ratchet.

Phil H

And IanT said:

'Whereas I was told to always use the ratchet to ensure a repeatable torque….and I do so without any problems in use… but each to their own…'

I think you're both right. The reason being it's important to use exactly the same pressure every time you use a micrometer. That's not easy to do and some are better at it than others. The ratchet is a simple way of improving consistency, but imperfect. I reckon a skilled operator develops a 'feel' making him more consistent than the average ratchet.

Being self-taught and cack-handed I always use the ratchet. I get reasonable rather than completely repeatable results. Perhaps one day I'll take better measurements without a ratchet; it'll take a fair bit more practice though!

Dave

Edited By SillyOldDuffer on 28/10/2017 20:25:59

[JonParticipant @jon]

Same here was given an analogue Moore and Wright micrometer (when they were good) at last place. Filed stuff up to the thou, easy to use just feel for the flat then ratchet in.
Rarely use mics nowadays except when want something cock on and thats a Mitutoyo didgi. Have many cased sets of quality English mics thats never seen daylight in 20 odd years, just too slow to use.

Verniers, phew i go through them like no tomorrow but still have a Mitutoyo analogue from 84 long relegated to scribing.
Clock type vernier never ever used horrible, except when over 8" length.
Much prefer the digi verniers but not the cheapies which are always aweful to use, eat batterys and need constant zeroing every time switched on. Yes i do have an Aldi cheapo some where forced to use for 7 days when had some stuff nicked at a show including a coolant proof Mitutoyo £130, never again and several other rock bottom chinese £1.50 to £5 each that are much better than Moore and Wright at £35.
Biggest killer for me is coolant, definately gone through 5 off £80 Mitutoyos and a chinese Moore and Wright £35 horrible annoying thing.
My coolant proof IP66 Mitutoyo vernier is in constant use pro, bought sometime in last decade when they first came out. Dropped dozens of times £46 brand new genuine serial number checks out should be £130, money well spent.

[Neil WyattModerator @neilwyatt]

The National Physical Laboratory says that if your micrometer has a ratchet, you should always use it on the first click.

It's worth downloading the docuiment that link connects to.

It also says a lot of other interesting things, like don't by callipers or micrometers too accurate for your needs as you are just wasting money and time, to make sure everything has stabilised at room temperature, and to be aware that micrometers will give different readings depending onw hether you use them hand held or in a clamp or in different orientations.

Neil.

[Phil H1Participant @philh196021]

Neil,

Right or wrong, anybody caught using the ratchet would be mocked. When everyone calmed down and stopped the chimpanzee noises, the answers were actually quite reasonable.

One reason (and I have definitely come across this problem) is that over time, the ratchet 'wears' and if you try measuring slip gauges, the ratchet fails to achieve the correct 'feel' and hence the correct measurement – and that is using a properly calibrated toolroom micrometer.

The second reason hinted at by Dave's answer is the need to try and train into the apprentice the correct 'feel'. This is important because there are many situations e.g., using slip gauges to measure a precise gap where a ratchet is obviously not available.

Finally, this might not apply anymore but many of the very best mircometers simply did not have a ratchet.

Phil H

[thaiguzziParticipant @thaiguzzi]

Posted by ChrisH on 28/10/2017 10:47:31:

Andrew – I like you method of working, very sound, but not all – perhaps very few, I don't know – of us have the grinding facilities to accurately grind hole plug gauges parallel and to size, we have to make do with the measuring tools we have, but as you say, you can't have too many micrometers, inside and out! I need a depth one now too.

thaiguzzi – quality verniers are very good but the problem using them you have identified, eyesight. That doesn't get any better as you get older and a lot of us here are not so young as we like to think! (Think mind making promises the body can't keep anymore. You think you are still 27 but the reality is more like 72!). That is why digital and to a slightly lesser extent dial calipers have their attraction, big figures easy to read.

Chris

Bump.

Well, 3 years later, just turned 60, and my Mit verniers are finally getting awkward to read on the imperial scale.

Being a Luddite, and refusing to have anything to do with digital, batteries or electronics, i am now looking at dial calipers…..metric and imperial….

[Speedy Builder5Participant @speedybuilder5]

I do like Dial callipers, but of course you would need one in metric and another in imperial – or would one? Has anyone seen a digital dial calliper where the analogue face of the dial could change between the two measurement systems. That would be a neat idea.

Its a bit like the speedo on your car, do you prefer dial or digital ?

[Clive FosterParticipant @clivefoster55965]

My solution to the vernier scale reading problem was to find some with double length verniers, 2" or metric equivalent, rather than the usual 1". The markings are deeper and clearer and the more open scale is easier to read.

Mine are M&W but some other breeds around, Mauser(?). Dont have internal scale knife edges tho' so you have to subtract a correction factor for internal work.

I have apiar of Mitutoyo 8" / 200 mm dial calipers for general work. The extra lenght makes them a little cumbersome at times but is often handy. But I work 12" to the foot scale. Not models.

Clive

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