Dial Indicators

[MWParticipant @mw27036]

Like John said, the words are essentially meaningless without further information so they are largely contextual and synonymous in their relationship. There are tons of words like this. 

The English language is a wild kind of animal and any attempt to constrain the nebulous nature of its words have always failed. We wouldn't want to end up like France where we have a government department to make up new words just to stop "foreign influences" spreading into it, whether its people like it or not. 

This is also reflected in the way England practices law, it is basically revised "as it goes along" on a case by case basis to reflect the opinions of the people at the time. Other nations have a fixed constitution that fights a never ending battle of amendments to keep up with what people want in a rather slow fashion.

 

Michael W

Edited By Michael Walters on 13/02/2016 11:39:39

Edited By Michael Walters on 13/02/2016 11:46:00

[AjohnwParticipant @ajohnw51620]

Standards are a form of documentation. As time goes on these tend to contain more and more words and less useful content for the people who want to make use of them. The same is largely true of books on technical subjects. It seems this is very true of the UK's tax laws. What we have is good for some but not for the people who collect it.

Having run out of things to do or having bods about with nothing useful to do the next step is perhaps we had better define the words we use which masks the fundamental aspects even further. Worse still some one who doesn't fully understand something may be employed to produce the documentation as the person who does understand it costs more or just doesn't want to do it. That's what has happened in the software area. The same will be true in other areas.

Really the fundamental aspect of what this thread has some how now got into was summed up earlier. Given that something needs to be produced to some limit = error there is little point trying to do this with something that inherently has worse errors.

I'm reminded a of a very senior manager who paid some one to do something and report on it. He sent it back because the report didn't contain enough pages. It did contain the needed information.

John

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[KWILParticipant @kwil]

Not only senior managers, I recall being able to write down all the necessary information about a particular geographical feature on a one and one half pages only to be castigated for not taking 10 pages of waffle like the rest of the class!!

I resigned from that subject as soon as could.

[Michael GilliganParticipant @michaelgilligan61133]

Before this discussion descends into farce:

Would those who object so strongly to the use of the word 'precision' in this context PLEASE take a few moments to consider its very simple etymology.

pre … as in before/prior/previously

cision … as in cut/marked

Thus [for example] the pre-cut marks on our measuring scale dictate its precision … and most other technical uses of the word can be traced back to this concept.

In my opinion, it is a very reasonable word to use.

MichaelG.

[CirclipParticipant @circlip]

NASA must be rubbing their hands in anticipation of all the prospective cheap supplier applications.

I fort muddle injineerin was supposed to be a relaxing hobby.

Regards Ian.

[pgk pgkParticipant @pgkpgk17461]

That caused me to look up the etymology which points towards the latin as meaning to 'cut off' as opposed to suggestions of precutting. (my professional life was spent incising and excising but the only pre-cising I did was reading a text book before picking up the scalpel)

But as my English graduate daughter says (mostly to wind me up) – language is organic (heck i hate that.. everything now is 'organic' and that as a word is really bastardised from it's true meaning)

Anyway, rant over, and the term precision will have evolved from meaning 'to cut something off' to 'to cut something off to the correct length' to 'to cut something off to a length of great accuracy' and then twisted as an expression to mean 'of great accuracy'. Doubtless the Romans first use in latin was a happy hack with a Gladius.

edit: or did the romans mean 'measure twice, cut once?'

Edited By pgk pgk on 13/02/2016 13:04:21

[Michael GilliganParticipant @michaelgilligan61133]

Posted by pgk pgk on 13/02/2016 13:01:56:

That caused me to look up the etymology which points towards the latin as meaning to 'cut off' as opposed to suggestions of precutting.

.

I fully accept that 'cut-off' is the more common meaning than 'cut-into' … but the 'pre' sits outside that.

 … the verb praecidere: prae-‘in advance’ + caedere ‘to cut.’

MichaelG.

Edited By Michael Gilligan on 13/02/2016 13:31:31

[Neil WyattModerator @neilwyatt]

This spec for an 'affordable' Mitutoyu digital micrometer is an interesting example of how these ideas can help judge the actual performance of a tool.

The resolution (which will combine with operator technique to give precision) is given as 0.001mm.

The accuracy is given as +/- 2.0 um which sounds awfully good, doesn't it?

Until you convert to mm and see +/- 2.0 um is a window of 0.004mm, which is considerably less fine than the resolution.

Neil

 

P.s. you can pay around ten times as much and get one with the 0.0001mm resolution and an accuracy of +/- 0.5 um

Edited By Neil Wyatt on 13/02/2016 13:19:23

Edited By Neil Wyatt on 13/02/2016 13:23:18

[AjohnwParticipant @ajohnw51620]

I just object to the fallacious pedantic use of some English words especially when there is no need for it. Also inventing words when there is an identical one already available. Not always that simple. I might call some one a dog or I might call them a cur. Both mean dog but they may have different implications. A dog breeder may see the word cur as meaning something entirely different and not take offence. They should though Quote "An aggressive or unkempt dog, especially a mongrel." Another case of a field choosing to use a word incorrectly.

On topic – I wonder if people realise that normal DTI's are more of a comparative rather than a measuring device especially at the resolutions they generally offer. That's down to them having higher levels of accumulated error over distance than some other devices.

Again all that matters is error, precision and accuracy are irrelevant without further qualifications. And the device being used sets limits anyway.

LOL That change of formatting caused by pasting something in seems to have a font size similar to what other forums use – I didn't do it on purpose. Another example. As it's come out like that people might put emphasis on the statement that I didn't intend.

John

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[pgk pgkParticipant @pgkpgk17461]

Posted by Michael Gilligan on 13/02/2016 13:13:01:

I fully accept that 'cut-off' is the more common meaning than 'cut-into' … but the 'pre' sits outside that.

… the verb praecidere: prae-‘in advance’ + caedere ‘to cut.’

MichaelG.

Edited By Michael Gilligan on 13/02/2016 13:31:31

Thinking about that caused me to chuckle… perhaps when our Latin cousins compounded the verb they were sitting on the branch of a tree, saw in hand and thought it better to cut in advance of their position rather than nearer the trunk. Or they looked at the enemy column marching over the hill and thought it a good idea to cut off that advance. Or, as my daughter would insist, that the meaning of words is within their context and contemporary usage. Perhaps a Roman butcher was dicing stewing steak and selling it as precut. That's where science and art fail to meet.

[Roderick JenkinsParticipant @roderickjenkins93242]

I think we just have to accept that words have, as been said, different meanings in their context. Remembering a previous discussion, I don't think we will ever convince the man in the street (or indeed the practising engineer) that an elastic band is tougher than an HT bolt. Words get hijacked: the QA/H&S community have decided, somewhat arbitrarily as far as I can see, that "shall" is mandatory. Reporters have decide that "epicentre" means the centre of the centre (whatever that means) rather than the nearest we can get to the centre of the earthquake on the surface. I like Neil's differentiation between resolution and accuracy – that is how I have understood it. Perhaps the word precision is best left out of it. Mostly, though I'm with Humpty Dumpty:

"When I use word,' Humpty Dumpty said in rather a scornful tone, 'it means just what I chose it to mean – neither more nor less.'

Cheers,

Rod

[SillyOldDufferModerator @sillyoldduffer]

One of my books contains this advice about Dial Indicators. "When using a dial indicator on a surface plate for accurate measurement of gauges and fixtures, it is quite a good plan to tap the table or plate with a hide or rubber mallet when the indicator is set and just before taking the reading. However good an indicator is being used, there is always the possibility of a certain amount of "stiction" (a modern colloquialism) in the movement, and the vibration thus set up tends to make conditions more or less uniform for each reading"

So there you have it: the cure for a sticky dial indicator is to hit it with a hammer.

By the way Sulfer has been the correct UK spelling since 1992. Please don't shoot the messenger!

[Michael GilliganParticipant @michaelgilligan61133]

MichaelGPosted by Ajohnw on 13/02/2016 14:01:36:

On topic – I wonder if people realise that normal DTI's are more of a comparative rather than a measuring device

.

John,

I can't speak for "people", but; for myself … Yes

This was the reason behind my response to Neil, on page_1.

MichaelG.

[AjohnwParticipant @ajohnw51620]

Shall as I understand it came into wide spread use in the world of software first and spread from there. Specifications have long been seen as a must in that particular area. Now there is a tendency to mask what processes are actually needed by use of the two words, verification and validation. That has spread too, see the wiki. Validation seems to have some legal connotations so looking at some definitions of QC/QA maybe the meanings should be reversed. Either way I have seen thick bunches of paper that don't really mention a sensible way of starting and finishing some related task at all. Written by an august body of people who are trying to generate a standard for people to work to. I reckon this happens because the basic processes that should be used are simple and can be covered by simply stating what should be done in respect to specifications. A lot less paper. The problem with those is that in some instances and areas complete specifications are impossible to write – no one could actually state that as it would indicate that they don't know what they are doing. However if some one works in development, many jobs start like that. Just an idea of what is needed. Bull something or the other springs to mind.

John

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[SillyOldDufferModerator @sillyoldduffer]

Posted by Ajohnw on 13/02/2016 19:19:13:

Shall as I understand it came into wide spread use in the world of software first and spread from there. –

I'm no expert but I always thought that the 'shall' wording was just standard commercial contract speak used to express requirements, though like John my experience is software related too.

I used to be in a team that wrote Requirements for hardware, software and services. The form was to specify essential requirements in the form "The widget shall be pink." This would be issued to industry who would reply with a compliance statement like "The widget will be pink". If the price was agreeable a contract would eventually be issued in the form "The widget must be pink." and this would be legally binding.

The purpose of this rigmarole was to allow clarity and agreement to be negotiated before finally committing to contract. The specification of a large IT system can contain thousands of individual requirements and it pays to get good agreement between customer and provider up front especially where sub-contractors are involved too.

Words become seriously important when a contract is in dispute. I once spent over two hours arguing with a supplier's lawyers about the contractual meaning of the word "all" and lost the common sense argument because poor wording in another part of the contract accidentally contradicted the usual meaning of "all".

My feeling is that chaps using machines to make real things have much more fun in their work than us poor s*ds in offices!

[AjohnwParticipant @ajohnw51620]

I'm basically a designer. Might be why I have had some success with certain type of software. I design it rather that write it. Or perhaps it gives me a better understanding of structure. The last time I was sold by the company I worked for the job turned out to be electronics and software. Software was something I had used as a design tool well before PC's were about. Electronics only trivially but as spooky as it might seem 2 years or so before being sold I was put into a job that allowed me to increase my electronic skills markedly. Followed by another 2 to pick up the field I would be working in.

My impression of the contractual world of putting software out to be produced by a 3rd party is that specifications are often used as a get out by the people that actually produce it. It works because specifying things like what software should do functionally and what equipment it must run on can be extremely difficult. I understand that the public services have discovered this to their cost on numerous occasions.

John

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[HopperParticipant @hopper]

There is absolutely no point in getting too pedantic about the meanings of words.

Words have no meaning at all. You can't cut a word open and find its meaning.

The meaning is assigned to the word by the sayer as he/she says it.

The hearer then assigns his/her meaning to the word when they hear it.

And appealing to the Oxford English Dictionary (or any other dictionary) is not a failsafe solution. Dictionaries are descriptive, not prescriptive. They define the common meanings of words based on current and past useage out there in the real world. The useage of words to mean different things is constantly changing. One only needs to read Chaucer or Shakespeare or even Hemingway to see that.

As dictionaries are based on collected spoken and written examples of real world useage, they frequently do not include arcane specialist uses in esoteric fields such as engineering, archery, shooting, rap songs etc.

Old words are assigned new meanings all the time. Some of them make it into common useage, others fade away or stay in their remote specialist corner. If the pedants reigned supreme and we only used the dictionary meanings of words with no exceptions, we would all be still talking like Chaucer's character The Reeve ( a cranky old carpenter.).

Sik lay the maunciple on a maladye;
Men wenden wisly that he sholde dye.
For which this millere stal bothe mele and corn
And hundred tyme moore than biforn;
For therbiforn he stal but curteisly,
But now he was a theef outrageously.

 

Edited By Hopper on 14/02/2016 04:32:51

Edited By Hopper on 14/02/2016 04:37:48

[Neil WyattModerator @neilwyatt]

That BIPL document I linked to explains the coining of a new French word mesurage, meaning 'to measure', because the word mesure was felt to have too may meanings in common use. Engilsh has both 'to measure' and 'measurement' that distinguish the verb from the noun.

Neil

P.S. Thanks for 'maunciple'

[AjohnwParticipant @ajohnw51620]

It's also possible to have a measure of whisky too Neil. Not that this is a problem. Things like the meaning of all as mentioned earlier viewed legally can have dire consequences..

That's the problem with things like deciding what validation and verification means. All sorts might get mentioned to try and cover anything that might crop up. Something may get missed but the result is a big increase in verbosity.

In real term those 2 words can be viewed as meaning there are 2 aspects. A specification for people to work to and the question is that specification correct. Either of these can mean that something or the other has to meet certain legal requirements. In context that can't be misunderstood.

However:

In this sort of area it's often all mind games really. Take the "thing" that popped up before ISO9000. All it meant was that people needed to write down what they do. That causes them to think more about it. It didn't last long and ISO9000 seems to be, well some just don't do things correctly so go a bit further. Terms like stakeholders cause people to think differently about certain aspects as does engineering by numbers, meeting customers expectations and many others. The terms are deliberately introduced into various areas to change peoples behaviour or even opinions. Weapons of mass destruction is an interesting one.

John

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[KWILParticipant @kwil]

The problem with ISO9000 was that it became too prescriptive and a means to its own end. Those that ran the setup became obsessive as if ISO9000 was the only thing that mattered.

I found there was nothing wrong with having a Design/Job/Project requirement that the Customer thought was needed, but the subsequent "Definition" phase was an essential stage in order to set out what was possible/ or to be achieved. Within this stage the Agreed Acceptance Tests to be undertaken to confirm achievement were of necessity to be included, without which argument and disention is inevitable.

[Michael GilliganParticipant @michaelgilligan61133]

'Dial Indicators' to 'Weapons of Mass Destruction' within in four pages.

… What a forum this is !!

MichaelG.

.

P.S. … On the subject of ambiguity;

let's invite Einstein and the Pope to contribute definitions of 'Mass'

[Jerry WrayParticipant @jerrywray14030]

If you look into the general world in which we in the UK have to operate I think you might find that the words 'should' and 'must' are equavalent and that any atempt to differentiate them will eventually lead you an appearance in front of a man or woman garbed in a wig and red coat sitting in judgement on you where formality is the order of the day, where every word you utter is written down and being told to justify yourself.

Jerry

[AjohnwParticipant @ajohnw51620]

I don't know Jerry Should indicates some scope for variation. Shall doesn't. Switching to must later should be pointless but it seems legal people think otherwise – probably because a lot of their income arises from choice of words.

Yes Michael. Having had some involvement in this sort of area it disturbs me as does voting on the EU when people wont have solid facts about what actually goes on.

John

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[Howard LewisParticipant @howardlewis46836]

Since a thread on Dial Test Indicators has become one of semantics, remember the story of the foreign gentleman who fell off a cross channel ferry.

As he floundered in the cold water, he cried "I will drown. No one shall save me".

So the crew took him at his word; and he did!

Howard

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