Converting a Vernier Height Gage to Digital?

[PeteParticipant @pete41194]

I had to think really hard before posting about this since many will disagree with me. But the artical in the July issue of MEW does require some additional information that wasn't properly covered.

It's not my place to say what anyone should or shouldn't do with anything they happen to own or buy. But due to inexperience, People following that artical may end up with far less than they started with. Starret and Mitutoyo to name just 2 manufactures today still produce high quality vernier height gages. And there were litterly dozens more in the past. All those very well made vernier height gages are in fact a lot more accurate (but slower to read) than most high cost and barely affordable dial and digital models built today. There's not enough information around, But it really should be closer to comman knowlege. You should search for what the terms actually mean when buying accurate metrology equipment. Accuracy and resolution are not properly understood and confused by far too many.

If you were to spend less than an hour learning the proper way to read a vernier scale, And a bit of time checking the accuracys obtainable with them against what the much higher priced dial and digital ones are capable of? Then personaly I don't think I'd be all that quick to convert a well made but older vernier gage over to digital. And I'm saying that because I bought a brand new digital height gage built by Mitutoyo. Both Mitutoyo and Starrett built very high quality equipment with the prices to match. So if they build far in excess of $1,000.00 height gages with all the technology they have avalible, Yet they state the repeatable accuracys are only within a couple of .001?

Personaly I fail to see where adapting a rather cheaply made Chinese digital scale will give you anything approaching what the original vernier scale does for repeatable accuracy on a tool that was well made and accurate to begin with. Yes it's faster, But a tape measure is also much faster and much cheaper than a height gage.

If the accuracys avalible from those cheaper built digital height gages are good enough for what your doing? Then I'd just buy one of those and refrain from making irreversable modifications to an old tool that will be mostly worthless to anyone else once your done with it.

Pete

[PeteParticipant @pete41194]

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Pete, to be fair to the author of the article, he hasn't suggested converting an expensive highly accurate height gauge. One advantage as mentioned, is that the digital readout can be zeroed at any point along the scale. The original readout has not been made useless, as it is written in the text that should the battery fail in the digital readout the analogue scale can still be used. As far as I can see, there is no clam that this is of any higher accuracy than a high quality vernier height gauge.

I see this article as taking a relatively cheap height gauge and a reasonable priced digital readout to make an inexpensive height gauge to ones preference, which should have a reasonable amount of accuracy, providing some thought and care is taken during the conversion.

Regards Nick.

[John Stevenson 1Participant @johnstevenson1]

Devils advocate here.

If the vernier ones are so accurate and so reliable why don't they exist in industry any more ?

Two local companies i visit, one an aerospace company and one that actually makes CMM measuring machines only have digital hight gauges in their inspection labs.

??????

John S.

[Ian PParticipant @ianp]

Posted by John Stevenson on 09/06/2012 09:34:40:

Devils advocate here.

If the vernier ones are so accurate and so reliable why don't they exist in industry any more ?

Two local companies i visit, one an aerospace company and one that actually makes CMM measuring machines only have digital hight gauges in their inspection labs.

??????

John S.

Probably several complex reasons,

Because its cheaper to make a digital one

Digital is easier and quicker to read,

It makes the company metrology lab look high tech and up to date.

I think manufacturing cost is the main driving force

Ian

[NJHParticipant @njh]

Well I didn't have a height gauge and a couple of years ago I got a 18" digital version ( from our friends at Machine DRO) as a Christmas present from my wife.   ( How did she know that I would like that I wonder?) It is a very solid, well made and finished item. It does have a couple of advantages over the normal vernier :-

1. It is MUCH easier to read without the need for magnifying glasses (for failing eyes)

2. It reads in either metric or imperial and converts between them at the touch of a button.

3. A zero point can be set at any point. This is very useful as a centre line can be set out at the appropriate distance from the surface plate and scribed, the gauge zeroed then plus and minus dimensions easily entered and scribed.

4. It is relatively cheap – about 1/6 of the cost of a Mitutoyo vernier (which would thus be way out of my league.)

In all I find it very useful.

If I had a good quality vernier would I butcher it to add a digital facility?

NO – I hate messing with good equipment – but I might still buy the digital version for the convenience and flexibility of its operation.

Regards

Norman

 

Edited By NJH on 09/06/2012 10:52:06

Edited By NJH on 09/06/2012 10:52:55

Edited By NJH on 09/06/2012 11:12:08

[Martin WParticipant @martinw]

Hi

While I would not advocate destroying/converting a quality measuring instrument the article does, in my opinion, have merit in showing what can be done to make life easier in the 'Amateur's' workshop.

The comments about the accuracy of the old vernier instruments compared to the modern digital instruments doesn't really hold water. Modern digital measuring instruments are now offering resolutions to 0.001mm, 1 micron, with an accuracy better than + 0.002mm. They also have the capability of setting the '0' at any point, making relative measurements, measure in metric or imperial units, are easily read and come at a reasonable price. No wonder they are finding their way into everyday engineering situations.

No I am not a youngster looking for an easy way out but well into retirement and still ready to accept new ideas when they have merit. That said I still have and treasure my father's vernier calliper made by P Roch, Rolle, Switzerland complete with its purple lined case, circa 1939. Do I use it, no, would I ever butcher it, of course not.

Modern WELL MADE measuring instruments are every bit as good or even better than the items they replace.

Just my penny worth .

Martin W

 PS

Hi Norm

Looks like I was cogitating about my post when you submitted yours, sorry about the repeats but at least we are coming from a similar direction.

Cheers 

Edited By Martin W on 09/06/2012 11:31:11

[NJHParticipant @njh]

Hi Martin

Well having clocked up 68 years a couple of days ago I too do a lot of "cogitating" these days – I guess I am an "Old Cogitater" – or is that Old Codger ??

I do all this for fun and think myself very lucky to have found an interest which is wholly absorbing and seems to offer limitless possibilities for further discovery and enjoyment.

Cheers

Norman

[Tony Pratt 1Participant @tonypratt1]

Digital readouts/calipers/height gauges etc are so much easier to read and extremely convenient. To the unwary they also give the impression of greater accuracy but in reality the machine or instruments precision or otherwise is unchanged.

Tony

[John Stevenson 1Participant @johnstevenson1]

Posted by Ian Phillips on 09/06/2012 09:51:20:

It makes the company metrology lab look high tech and up to date.

Ian

That only works if the fancy gear is up to spec and these places are checked out regulary.

I have two or three vernier high gauges but none have been checked, how do I know 12" is 12" ?

Ok for smaller measurements you could use slip gauges for the crunch is who's checked them ad i mean truthfully ?

John S.

[PeteParticipant @pete41194]

Yes,I do know what the artical says, But it also doesn't say what accuracys you can resonablly expect. And as I mentioned, Far too many think because there's all those zeros after the decimal point, Then anything digital has to be really accurate no matter how cheap it is to buy. And nowhere does it mention or warn against destroying any value that's left on all those finely built Vernier Gages. There's a lot of those older height gages around now at fairly cheap prices, And yes a cheap one was used in that artical. Personaly I'd hate to see that type of work done on some of these old but fine tools due to inexperience and thinking it's a great idea to do so. If you do know your going to destroy a tools value and still chose to do so? That's fine, But a bit illogical to me.

And I'd also agree that very accurate digital equipment can be bought today that is extremly accurate. But not normaly at a price most of us would be happy to pay. I know exactly how much it hurt to buy my 12" digital Mitutoyo, And it's repeatable accuracy. But I also have a very good set of gage blocks that do allow accurate checks to be done. So if and when it's rarely required, I can use my height gage for accurate measurements beyond the inaccuracys of the tool itself.

Industry has gone to digital equipment for many reasons, Less mistakes, speed of measurements, ease of usage would be just 3.That's also why I've bought some digital equipment. LOL, Due to age and not needing that magnifying glass is really nice too.

I guess the main reason I started this thread was it cost me far too much to lean the little I do know the hard way. I wouldn't like to see anyone else have to do the same. Maybe I'm wrong, But I still happen to think forums like these are or should be where the more experienced can help to educate the less experienced. And since this sub forum is for anything in MEW. I figured this was the correct place to add what I thought was missed in that artical. Overall I do think it was well done. It's just that it missed those important points.

And as usual, John Stevenson is 100% correct, But that's another reason I bought good gage blocks. I can calibrate and check my own equipment so they all agree with each other. Maybe not to National recognised standards. But my gage blocks are my standards. Yearly metrology lab recertification probably isn't needed by the vast majority here either. Being within a few thou is more than good enough for almost anything most including myself will normaly need to do.

But If this thread helps even one person to understand the value of some of the older tooling and the difference between resolution and accuracy, Then it will have been worth it IMO.

Pete

[jim bothParticipant @jimboth37830]

just chucking my two penny's worth.

if the technology had been about, digital would have been used years ago.

[Sub MandrelParticipant @submandrel]

I have a mid-price vernier and several digital ones. I never use the manual one, not least because it took me an evening to adjust the vernier so it reads zero at zero and I therefore don't wholly trust it. That said it does now agree with my digitral callipers when applied to the 1" standard test bar supplied with my (digital) 2" mike.

Some years ago, someone wrote an article about restoring an original first-generation Mitutoyo digital micrometer!

 

But I wopuldn't advocate buthchering a nice piece of kit to 'digitise' it. Why not just take the jaw off the end of a digital calliper, grind the other jaw to shape or fit a gauge plate scriber, and fit the whole shebang to a base? It should be easy to get the scale within a fraction of a degree of vertical, and a basic trig will tell you that any remaining error will be vanishingly small.

 

Edit – quick check, if the caliper is a 6" model and its 1 degree out (easily seen to be out by eye) the error at 6" will be just less than 0.001" Half a degree out (still visible to the eye) and the error would be less than a quarter of a thou.

Neil.

Edited By Stub Mandrel on 09/06/2012 21:45:59

[Martin WParticipant @martinw]

Pete

I totally agree with the sentiments of your last post. There is much made of the number of zeros after the decimal point with scant regard or little understanding as to resolution, accuracy and repeatability which can lead the unwary and over eager into problems. That said the price of electronic/digital devices is constantly being reduced and good quality kit is becoming affordable for the non-professional user, even if some of the 'Branded' makes still charge inflated prices probably put down to traceability, inspection, calibration etc which is to a degree valid.

However there are companies that offer what appears to be high specification instruments at reasonable prices as well as their top of the line kit, usual exclusion clause, such as this one.

Keep posting as its good to have new blood on the forums.

Cheers

Martin

[John Stevenson 1Participant @johnstevenson1]

I do agree with some of the sentiment here, just because it's digital doesn't mean to say it's the dogs bollocks.

Some things are best left manual, I bought these some while ago and whilst they work fine I cannot see how they are better that the other manual set i have, both are good for a thou.

John S.

[PeteParticipant @pete41194]

Hi Martin,

Thanks for the encouragement to post more often. Norman will know me and my thoughts, John Stevenson will also know me from the HSM forum.LOL,Then again they may not freely admit to that fact. There's a few others I can place due to their user names.

There is, And thankfully it is very uncomman, The very rare person who gets a weird perverse satisfaction from knowingly posting incorrect information. I'm not the type who tollerates games like that at the expence of the inexperienced. So far I've yet to see one of those on this forum. So I guess I should post or at least spend more time here. Overall there is much less argueing, And it seems much more actual logic used on this forum, So that's a nice refreshing change.

Well except for that last picture of Sir Johns that is. I do have to laugh every time I see it.

Pete

Edited By Pete on 09/06/2012 23:57:05

[Sub MandrelParticipant @submandrel]

I thought it was a CNC machine tool – I know they can round hexagons into cylinders faster than any lathe.

Neil

[jason udallParticipant @jasonudall57142]

Not arguing with the "accuracy vs resolution" warning but the article in MEW shows a , {to me}, sympathetic ADDITION of a digital scale to an existing instrument.

Agreed , strapping a digital scale to a base and using a out of square arm and column will not achieve the expected (or advertised ) level of accuracy , but again that’s not what was done.

Using a height gage (sic) as a marking out tool is more of a "sin" {to me} but then I am new to home engineering.

but hey , I come to this from electronics….component tolerances 0.1 to 20 % ,device parameters (for same device ) of 10 to 1,000 …it all had to work within spec. first to 1000 th off the line.

btw

Always wonder why no tolerances shown on MEW drawings ,It seems in Mechanical engineering that production drawings are often tolerance in "strange" ways ..I have seen features tolerenced such that other features entirely disapear..if dimensions exert to limits. Seems to be getting worst too…are they relying on 3sigma?

Rdgs

[David Clark 13Participant @davidclark13]

Hi Jason U

No tolerences because model engineers make one part to fit the next and so on.

Rarely do they need to be interchangeable.

regards David

[jason udallParticipant @jasonudall57142]

Thanks…Fits might help in some cases….I all ways seem to try for too "nice" a fit…learning that this is not always desirable…friction vs sealing…oh well another engineering comomise compromise….

Edited By jason udall on 11/06/2012 11:36:58

[Jeff DaymanParticipant @jeffdayman43397]

"Some things are best left manual, I bought these some while ago and whilst they work fine I cannot see how they are better that the other manual set i have, both are good for a thou."

John – Your blue digital device looks like a good one. If you ever need more accuracy, you might try one from North America (always identifiable by their red paint and flashing display) – they are accurate to at least a tenth of a thou, especially on rusty fittings.

JD

[Martin WParticipant @martinw]

Jeff & John S

I have a smaller version of this measuring instrument, probably designed for the amateur, and find it very useful for putting calibrated horizontal knurling patterns on a variety of material with cross sectional profiles from round through to square. The big advantage over a normal knurling tool is that these can produce an intermittent pattern which gives an indication of part rotation when making fine adjustments

Martin

[Nicholas FarrParticipant @nicholasfarr14254]

Hi John, I wonder! could such a display be fitted to my old 15" adjustable spanner? It would make it into both a metric and a imperial one then, wouldn't it?

Regards Nick.

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