Vernier vs Micrometer

[Steve GarnettParticipant @stevegarnett62550]

Posted by Nicholas Farr on 27/01/2012 02:08:02:

 

Not wanting to put anyone down, but isn’t the term “digital vernier” incorrect? A vernier being an graduated scale which is read against a different graduated scale, so that sub devisions can be easyly read. Claipers sould be refered to as; claipers, vernier calipers or digital clipers. Micrometers should be refered to as; micrometers, vernier micrometers or digital micrometers, I know they can be prefixed with metric/imperial/fractional, and/or a specific type, or am I wrong, or being pedantic.

 

 

Er, sort-of wrong I’m afraid. The term ‘digital Vernier’ does describe, at least basically, how they work. If you want to see exactly what I mean, probably the best thing to look at is the original patent from 1983, although being worded in patent jargonese doesn’t exactly help one’s understanding… Looking at some of the illustrations may though, although the concept has been refined somewhat. But the basic idea that what amounts to the rotor and the stator being of different lengths, running against each other and providing a differing positional output proportional to incremental positioning stands – in other words, yes it is a Vernier-derived output, and it’s displayed digitally.

 

If I was going to be pedantic about it though, I’d say that it was a capacitive Vernier system with a digital display…

[The Merry MillerParticipant @themerrymiller]

I use the micrometer as a rule.

 

Len P.

 

 

[Anonymous]

Terry: ….which rather neatly illustrates my point.

 

Regards,

 

Andrew

 

PS: It’s for measuring lan-thanides.

[TerrydParticipant @terryd72465]

Hi Andrew,

 

My comment was, of course, tongue in cheek, pity there’s no such ‘Smiley’

 

Best regards

 

Terry

[TerrydParticipant @terryd72465]

Posted by Steve Garnett on 27/01/2012 12:24:15:

…………………………………… But the basic idea that what amounts to the rotor and the stator being of different lengths…………………………

 

If I was going to be pedantic about it though, I’d say that it was a capacitive Vernier system with a digital display…

Hi Steve,

 

I’m not sure what you mean by a ‘rotor’ and ‘stator’ in this context. Having read the petition several times now (my old brain takes it’s time to wake up these days). The petitioner describes a ‘scale’ and a ‘slider’. There is no rotation involved.

 

Confused regards,

 

Terry

[Peter HallParticipant @peterhall61789]

Posted by The Merry Miller on 27/01/2012 13:04:13:

I use the micrometer as a rule.

 

Len P.

 

 

You would probably find a ruler easier for that

 

Pete

[blowlampParticipant @blowlamp]

Posted by Peter Hall on 27/01/2012 15:27:35:

Posted by The Merry Miller on 27/01/2012 13:04:13:

I use the micrometer as a rule.

 

Len P.

 

 

You would probably find a ruler easier for that

 

Pete

 

 

OMG, Pete!

You don’t know what you’ve started now

 

 

Martin.

[Peter HallParticipant @peterhall61789]

Posted by blowlamp on 27/01/2012 15:31:06:

Posted by Peter Hall on 27/01/2012 15:27:35:

Posted by The Merry Miller on 27/01/2012 13:04:13:

I use the micrometer as a rule.

 

Len P.

 

 

You would probably find a ruler easier for that

 

Pete

 

 

OMG, Pete!

You don’t know what you’ve started now

 

 

Martin.

 

 

I think I do. I’m outta here…

 

Pete

[Anonymous]

Posted by Terryd on 27/01/2012 14:18:02:

 

My comment was, of course, tongue in cheek, pity there’s no such ‘Smiley’

 

Quite so, and taken as such. So was my reply!

 

Andrew

 

PS: I thought the original digital calipers, from pre-1983 used a Moire fringing effect?

[TerrydParticipant @terryd72465]

Posted by Andrew Johnston on 27/01/2012 15:56:52:

Posted by Terryd on 27/01/2012 14:18:02:

 

My comment was, of course, tongue in cheek, pity there’s no such ‘Smiley’

 

Quite so, and taken as such. So was my reply!

 

Andrew

 

PS: I thought the original digital calipers, from pre-1983 used a Moire fringing effect?

 

Hi Andrew,

 

What a coincidence! After reading the patent petition several times and sort of understanding it, it seems to me that the caliper output is provided basically by reading the resultant from overlapping, interfering sinusoidal inputs. I saw that as being a Moire effect.

 

The fact that there are two parallel but differential scales to give the fine readings I saw a second Moire effect overlapping the first. I had never heard of using Moire interference in that way before but that was the picture as I saw it. I think that the patent is concentrating not on the method but on the ability to carry all of the electronics, generating as well as processing on the slider itself.

 

I don’t think that it is really a Vernier scale, but differential scales generating a Moire pattern in the capacitance fields.

 

Regards

 

Terry

[The Merry MillerParticipant @themerrymiller]

My thoughts exactly Terry.

 

Len. P.

 

 

[Major DisasterParticipant @majordisaster]

I thought that we in the UK all used the Queen as a ruler.

Edited By Major Disaster on 27/01/2012 16:13:39

[Steve GarnettParticipant @stevegarnett62550]

Posted by Terryd on 27/01/2012 14:22:23:

Hi Steve,

 

I’m not sure what you mean by a ‘rotor’ and ‘stator’ in this context. Having read the petition several times now (my old brain takes it’s time to wake up these days). The petitioner describes a ‘scale’ and a ‘slider’. There is no rotation involved.

 

Confused regards,

 

I did say ‘what amounts to’ – because I couldn’t at that immediate time think of a suitable analogy. For me, scale and slider don’t really explain the relationship, even though I’ll freely admit that rotor and stator aren’t ideal. If you want to know why I thought of it though, it’s because this is the usual way that linear motor operation is explained – in terms of an unrolled rotor and stator.

 

No I’m not saying that a linear motor works the same way – it doesn’t. It’s just that there has to be a direct relationship between the parts, as there does with a capacitive sensor system, in the way that there clearly (to me) isn’t with a scale and a slider, which have no implied relationship at all.

 

I hope that’s a little clearer!

 

 

Edited By Steve Garnett on 27/01/2012 16:16:09

[SteveWParticipant @stevew54046]

Isn’t a mic a fancy G cramp and a vernier an adjustable spanner??

 

We all use what’s easiest I guess and gives repeatable measurements.

 

I’m never sure how accurate they are but a digial vernier is a lot easier to read to a degree of precision!

 

Steve W

[Steve GarnettParticipant @stevegarnett62550]

Posted by Terryd on 27/01/2012 16:07:04:

 

I don’t think that it is really a Vernier scale, but differential scales generating a Moire pattern in the capacitance fields.

 

So a Vernier system doesn’t rely on an interference effect? It may not be Moire patterning as it stands, but the principle is the same.

[Peter G. ShawParticipant @peterg-shaw75338]

Going back to the original question, I have owned/do own the following:

Imperial 0-1″ micrometer, 0.001 thou

Metric 0-25mm micrometer, resolution 0.01 mm

Metric 25-50mm micrometer, resolution 0.01 mm

0-150mm Vernier caliper, resolution 0.05mm

0-150mm dial caliper, resolution 0.02mm

0-150mm/0-6″ digital caliper, resolution 0.01mm/0.0005 thou (Digical 1)

0-150mm/0-6″ digital caliper, resolution 0.01mm/0.0005 thou (Digical 2)

0-150mm dial caliper, resolution 0.01mm

 

When I realised that there were various discrepancies, I bought the 25, 50 & 75mm Mitutoyo micrometer standards and set about checking everything. Obviously I am aware that touch can vary, as can temperature & dirt, so I attempted to eliminate as much as possible, eg by taking multiple readings.

Of these, digical 2 was found to be inaccurate whilst digical 1 always read slightly high. Or was it low? In any case, with a reading tolerance of ± 1 digit and 0.01mm, I did not think much of them. And then when I found the rate at which they ate batteries, I stopped using them.

 

The 0.02mm dial caliper was found to be consistently reading low, so was given away.

The 0.05mm Vernier caliper was found to be dead on. As was the 0.01 dial caliper by Starrett which was bought to replace the 0.02mm dial caliper and the two digital calipers.

The metric micrometers were found to be either dead on or reading +0.005 mm at maximum reading. Even the imperial was reasonably accurate. With these, knowing the maximum variation, I compensate as necessary, eg at 12.5mm I add 0.0025mm. Ok, I know it may not be correct, but it is the best I can do.

 

As has been said, there is the problem of taking accurate readings with the narrow jaws of the calipers: in fact, it was this difficulty which caused me to get out the micrometer and thus discover the various discrepancies. I now use, firstly the 0.05 vernier for general purpose measurements followed by either the micrometers or the Starrett dial caliper as seems most appropriate.

 

I still have the digital calipers, and do occasionally use the better of the two, but only when the measurement is not required to be particularly accurate.

 

Anybody want an inaccurate Workzone caliper from Aldi?

 

Regards,

 

Peter G. Shaw

[WolfieParticipant @wolfie]

Oh man don’t any of you lot give up the day job

Anyway I spent this aft cleaning the old thing up and its come up OK. Its a Moore and Wright and my mam reckons it was my granddads. And being as he’s been dead for nearly 30 years its probably laid there all that time. Looking at Terrys handy photos I have a 1″ micrometer in 0.001 increments.

It cleaned up OK but its stiff-ish especially in the lower half inch and I can’t use the little ratchet thing to turn it. The faces look ok and square.  Also it has some kind of deposits on the outer barrel which make it a bit difficult to read. You can see them in the pic, a sort of dark mottling.

 

Incidentally I checked it out against my digital vernier and the vernier was within half a thou every time.

Edited By Wolfie on 27/01/2012 16:55:57

[Billy MillsParticipant @billymills]

Peter what do you want for £8.00 a NPL certificate as well? Electronic calipers use mass produced printed circuits to produce the two electrode patterns so you can knock them out cheaply. Some makers select the best and junk the rest. Rework is not going to happen at the low cost end of the market.

 

The capacitance sensing and counting circuits often run all of the time that the battery is installed, the on/off switch may only disable the display so there is a small battery drain with some types. The cheaper models seem to have a higher drain than some high end models.

If that is a worry pop out the coin cell between uses. The batteries are worth buying at MEX, last year you could buy 5 silver oxide cells for £1.99.

 

Wolfie- try unscrewing the barrel and a drop of light oil on the thread.

 

[Brian Dickinson 2Participant @briandickinson2]

I just love how everybody tries to outdo the last post.

 

Keep em coming.

 

Bri

[Speedy Builder5Participant @speedybuilder5]

I have a fraction marked vernier calliper measuring to the nearest 1/128″ (0.0078″) on one side and mm on the other side. Sometimes helps with the old imperial fractional inch drawings.

[Anonymous]

I was under the impression that the early Mitutoyo digital calipers used two optical gratings at a slight angle to each other. So the Moire fringes were a true optical effect and nothing to do with verniers. Of course I could be wrong.

The reason I rarely use vernier calipers is because I have a full set of micrometers from 1″ to 16″ and nearly a full set of the metric equivalents. Where’s the smiley for a smug bar steward?

 

Regards,

 

Andrew

 

On a bit of a swerve I do use a vernier protractor occasionally, although I don’t find it that easy to use for measuring, as opposed to marking out.

 

[Sub MandrelParticipant @submandrel]

Referring WAAAAY back to my comment about .250″ and .251″ is that you really need something reading to ten times better than that (micrometer) to be sure…

 

That said all my vernier calipers (including a Workzone one) read 1.000 on the 1″ test bar for my 1-2″ micrometer.

 

Finally I think the correct description for the digital spanners is not “moire” but “quadrature” – generating an ouput through the comparison of two signals 90 degrees out of phase.

 

Neil

[Ian AbbottParticipant @ianabbott31222]

“…interfering sinusoidal inputs…”

 

Isn’t that when you stick your nose in where it ‘aint wanted?

 

And

 

Over the years, I’ve accumulated digital, vernier, dial and fractional callipers in metric and Imperial, and inside and outside mics. up to 6″.

 

Now, I can’t read any of them without a x10 loupe!

 

Ian

[Steve GarnettParticipant @stevegarnett62550]

Posted by Andrew Johnston on 27/01/2012 19:26:46:

 

 

I was under the impression that the early Mitutoyo digital calipers used two optical gratings at a slight angle to each other. So the Moire fringes were a true optical effect and nothing to do with verniers. Of course I could be wrong.

 

I don’t know – I’ve never been able to justify buying any of Mitutoyo’s calipers!

 

But along those lines, there’s one more interesting patent from 1987, which uses the word Vernier in the title, and works on both rotary and linear scales. Much clearer to understand, too.

 

US Patent 4,654,524

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Versaboss on 27/01/2012 10:02:12:

Hmm, I wonder what the subtle differences are between

– clalipers

– claipers

– clipers and

– calipers.

(N. Farr; 27. 1., 02:08 (too late or too early???) )

I only own the last type I believe, but I’m sure Wolfie would like to know also

Greetings, Hansrudolf

Hi Hansrudolf, opps! A bit of a late night after a long day I’m afraid, and at present I’m having to use my netbook with a mobile connection divice, which seemed to be dragging its heels a bit and losing conection at the time, but I was determined to finish my posting before retiring. They should all read calipers of course.

 

Regards Nick.

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