prferance between digital and manual measuring equipment?
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  1. #1
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    Default prferance between digital and manual measuring equipment?

    Well as of today there is no digital measuring equipment at work Im not exactually sure what brought this about but here is the story. I was called the the bosses office and asked to measure a partiucar compontent that had been machined with a set of mitutoyo digatal vernier it measured 105.01mm
    Then i was asked to measure it with a second pair of mitutoyo vernier and i got 105.03mm then again with starret and i got 105.00 then meausred again with the same three vernier and got the same measurment from each as previously mentioned. then the boss pulled out his personal set of mitutoya manual mics and measured the item at 105.02 spot on.

    I was then asked to take all the digital measuring equipment from the machine shop and R&D and crush them under the 30tonne hydrolic press. except for 2 of which i was to break in to pieces by hand and mount them on a plark saying we dont want this shit in our (specific department name) and then take all the crushed measuring equipment show the boss and dump them.

    As im sure you can imagine this was not a cheap exercise not only did i crush at least 5grand worth of equipment but it then had to be replaced with the manual version.

    I didnt think it was a good time to question his decision on this so i just said no problem and did as i was asked. (but while doing it i thought what a waste i could use a height gauge at home or a set of digital mics and vernier, oh well.)

    So what are your thoughts on my bosses actions and what do you prefer digital or manual measuring devices?

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    Default Wow.....

    Your first post! I would have a hard time believing you, had I not spent
    nearly 10 years working for just such an individual.

    This is more a display of how extreem an individual's nature can be,
    than a test of what is the best means of measure.

    Broken down to the basics, digital is based on the vernier system
    of measurement. It just replaces the human eye with a "see-er or reader"
    that is non-human. From one instrument to another, the
    tiny line in the sand has to be somewhere.

    In using a manual vernier calliper, try having 4 different human readers
    and see if the line of subjectivity isn't also variable. Just the same,
    the Boss is the Boss.

    m1m

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    What an idiot. (Your boss, I mean). Perhaps you might want to find him a copy of "The Fundamentals of Dimensional Metrology". Calipers and micrometers are not in the same class of measuring accuracy/precision/reliability. That goes for digital and vernier. Also, calibration of inspection tools is something that should be done before the job, and periodically.

    It's his money I guess, but thowing away what would have garnered high (local) prices on ebay will have to made up by someone. Maybe your next raise?

    Is he going to give instruction on the possible errors in reading vernier tools? User friendliness=less scrap, hence the advantage of digital.

    I too have worked (in a different industry) for the same kind of guy. I feel your pain.

    Greg

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    Question As long as 2 of you are on this.......

    here in north central US, the sky is falling !!
    survivalism is the game, forsaking ethics and
    yer fellow man in some cases.

    How's tricks down under?
    just curious.

    Cheers
    M1M

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    M1M

    Yes i know what you mean by being my first post i thought twice before posting. I'll see if i can get a pic of the plark and post it (it is quiet amusing). As far as extreme natures my boss is an old die marker who belives that its not good enough unless its perfect and im lead to belive that his temper is one to be reckoned with, altough i have not witnessed it first hand i still see a flicker of it on occasions. Having said this doing an apperentiship under such a person i dont belive is a bad thing, as i think at the end of the day it will make me a better tradsmen. Learning how to things the right way and how to get the perfect finish even if it means hand polishing dies to a mirror finish. (hand polishing hmmm.... i hate doing that so much, but i love standing back when its done and thinking yep thats as close perfect as you can get i made it and im proud of it)

    Anyway i kind of agree with the decission to scrap the digital stuff i personally prefer a dial vernier and manual micromiter i think it is more accurate and definitly more relaible.

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    Quote Originally Posted by machine1medic View Post
    here in north central US, the sky is falling !!
    survivalism is the game, forsaking ethics and
    yer fellow man in some cases.

    How's tricks down under?
    just curious.

    Cheers
    M1M
    The general population is fealling it there business closing down everwhere in my town alone today i heard on the radio there was 700 laid of from some of the larger industries rio tinto included. hoise prices are falling but are still higher then what they should be and i quite often here of and see very cheap things for sale cars bikes boats i guess people are needing the money for other things.

    As for me or my work place the orders keep comming in there expanding ( new bigger buildings more machines etc) and we only have a boput 20 people working there. We make electrial couplers for the mines and export all over the world im sure things will slow down for as well but i dont hink it will be anytime soon.

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    ...And in general we are lagging the U.S. by several months in things like unemployment. The current forecasts range from 7%+ to 9%+ by the end of the year, although job losses seem to be accelerating already. In my industry (airlines) business is off by 25-30%, more when you compare $ volumes. Car sales are down about 20%

    Australia didn't have a sub-prime lending thing, nor did our major banks buy any CDO's or swaps owing to tighter regulation. As a result there has been little downward pressure on house prices apart from the general fear which seems to be now setting in.

    More worrying for us is the huge decrease in volume and prices of iron ore, coal etc. We have enjoyed hefty federal budget surpluses (remember them?) for several years, but now tax revenues are down and stimulus spending is up. Taxes hikes can't be too far behind.

    I was doing my best to stimulate the economy but now it turns out those pesky credit card companies want their money back. Who knew?

    Greg

    (I was in Detroit a coupe of weeks ago, sobered and a little frightened by all the empty/for sale factories in the tool and die/ engineering section of town. We haven't seen anything like that here yet)

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    Hope your boss doesn't catch on that the earth isn't flat and at the center of the universe. That might really piss him off.

    The Mitutoyo digital equipment works just fine and might even help a company that wanted to do work in both metric and English units compete.

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    I think digital is waaaay better than analogue (vernier) as you won't mis-read it.
    The figure is what the figure is!
    However, if you want accuracy, then it's no good using a digital caliper or dial caliper or vernier caliper if you need to measure something to within a couple of thou (50 microns). You then need a mic.
    We have mitutoyo DIGITAL mics and set our diatest bore gauges from them.
    I can't believe the accuracy of the mics, check them with slips and if you set a slip pile of 8.529mm, the bloody mic reads it! Unbelievable.
    So I thinK your boss is mad, as he should have used a mic to check the job with!!!

    Oh, and please post the picture

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    Quote Originally Posted by ian3846 View Post
    So what are your thoughts on my bosses actions and what do you prefer digital or manual measuring devices?
    A relevant point which many fail to realize...

    ALL digital equipment has a ±1 least-significant digit error. This is one of the great universal truths.

    It doesn't make any difference what the quality or accuracy of the equipment is, nor the manufacturer, nor what parameter is being measured. This error is inherent in the way the digital information is accumulated, and it can't be removed.

    Note that this error term reflects the resolution of the instrument. If the readout displays half-thou (inch) increments, then the quantization error is ±0.0005". This must be added to all other errors in the equipment; it's not incorporated in those specs unless expressly stated.

    The Mitutoyo measurements you cited are within this ±1 LSD error, assuming a true value of 150.02 mm. The Starrett is not.

    I prefer high-quality mechanical instruments for precise measurements.

    If I expect comparable accuracy with mechanical and digital equipment, I require the accuracy spec on the digital items to be a factor of 10 tighter than the mechanical. I can read a mechanical display to a needle width or less. Digital instruments don't have needles.

    - Leigh

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    +1 for the arguement of comparing manual mics to digi calipers.


    -------

    Think Snow Eh!
    Ox

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    To my understanding, some high quality digital instruments resolve to an additional place not dispayed on the readout. They then interpolate and provide a bit more accuracy.

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    Quote Originally Posted by Peddler View Post
    To my understanding, some high quality digital instruments resolve to an additional place not dispayed on the readout. They then interpolate and provide a bit more accuracy.
    That's true, though it's not very common. Adding bits in the internal circuitry costs money.

    The number of digits displayed is a major selling point, so they usually display the low-order digit and marginalize it in the specs.

    As an example, I have a product that only needs an accuracy of ±0.1%. In fact, that's tighter than any user would need or expect.

    That's the resolution of a 10-bit ADC (the IC that does the actual conversion to digital). I started out with a 12-bit ADC (±0.025%), but in tracing through the error sources I ended up using an 18-bit (±0.0004%) so I could spec a ±0.1% limit of error with confidence.

    - Leigh

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    Default I need help with this ......

    Way way back I had to put some didgital-read-outs back on some
    Bridgeports and Tree mills.
    It was basicly just trying to get the best read-outs on the best mills.
    One was a "new" magnetic DRO, the others were still glass-scales.
    One of our electronic gu-ru's tryed to help me understand how all this
    digital stuff really works.
    It's been decades so please correct this or add to it as needed.

    He grouped the reading components as follows.
    1, Resolvers.
    2, Encoders.
    3, Pulse-generators
    and then decribed the differences and uses.

    He also spilt these into ?? direct-reading ?? maybe & vernier ??
    saying that in very "ultra"-tiny measurement, vernier is the only way
    it can happen due to the physical limiltations of spaceing.

    He also told me that in ?? either ? or both ??? cases; that
    the smallest increment measured, was half the smallest increment
    displayed. This he explained is because there is polarity?? or something like that,
    from every increment to the next on the scale.
    Other wise the instrument would have no way of "knowing"
    that we stopped moving and measuring, and now are going back
    in the opposite direction.

    Like this sorta {#*#*#*#*#*#*#*#*#*#*#*} one direction-counting.
    this {#*#*#*#*#*#*#*##*#*#*#*#*} is what the reader sees
    when we reverse directions.It rereads a # and so initiates displaying
    a distanse back toward where we came from.

    A digital instrument, by nature and function has no reason to be
    any less accurate than a mechanical instrument.

    As far back as this trade goes, or as far into the future.
    Accuracy is in the hands of the be-measurer.

    The human is either accurate or not.

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    It's really a matter of personal preference, of course. Mitutoyo digital stuff is amazingly good. As said before comparing a caliper to a mike is just nonsense- a caliper is never going to stack up. My Mit caliper routinely reads spot on, but if I want to split .01's of a millimeter then it's gotta be a mike. In cases where only a caliper will do, I check mine against a standard set to the same size roughly as what I'm measuring and check it, using the same portion of the jaws as will hit the work. That way I can gage the feel and pressure; this is especially useful when measuring internal features where only a portion of the tips are making contact.
    As mentioned above a lot has to do with feel and 4 guys with the same tool whether it's a mike or a caliper are likely to come up with 4 different results. I measure a lot of tiny sub 1mm size stuff and need to hit withing a couple of microns. I use regular Mit mikes, but again I check them against good plug gages routinely. A mike that's been calibrated to read correctly against gage blocks might be all over the map when checking little .09mm diameters at the very edge of the spindle and anvil. I've also yet to see a mike that didn't benefit from a little lapping in of the anvil/spindle faces. With my lapped in mikes I can hit +- .001mm but that's really using it as a comparative mike with a good set of gages to help.

    Your boss is nuts, but I like your attitude! Sometimes we can really benefit from crazy yet competent employers. Too bad you couldn't work a deal to salvage the equipment rather than scrapping it.

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    Hi Guys

    Thanks for all your input, its pretty much as i figured and many of your thoughts are the same as mine. I think the reason for the boss using his mics was not to compare the vernier to them but to show the vernier were not accurite. Even though most our work has a tolerance of .05mm which all the vernier tested would be well with in there is the odd part that requires a lot tighter tolerance like +.01 -0.0 and i belive this is where the problem lies. I know your goiong to say a tolerance like that should be measured with a mic and not a vernier and yes i do agree 100% but green button pushers seem to be to lazy to find them or to use them or maybe they dont know how to read them.......? (its not my department and not my business and i really would prefer to keep it that way) there for it seems vernier are being used to measure things they are not designed for. I dont see how going from digital to manual equipment will fix this but once again not kmy dept not my biss.

    (its not my department and not my business and i really would prefer to keep it that way) just thouht i would clarify this a little i was refering to machine shop and i work in the tool room, there fore i have very little to do the main production which is where most the problems are. Im happy in the tool room doing odd jobs and repairs making new dies foundry patterns etc etc a nice varity of work all done to the highest possible standard each day something new and different and with that comes a new challange.

    oh i nearly forgot we got our new measuring equipment today vey nice stuff indeed all mitotoya new mics, new vernier (dial vernier only .01 increments) and height gaugues telscopic gagues etc. Just like christmas but im glad im not paying the bill.

    Ian

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    An expensive way to make a point, even if it does lead to an improved product.
    Should have made an attempt to sell off the digital stuff, IMO, but some bosses just are like that, and want to make a grandiose show of their displeasure.
    I wouldn't want to go golfing with your boss and let him borrow my clubs...

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    That's a scary level of stupidity. I assume you quit the next day? Working with such an impulsive and emotionally uncontrolled boss is not a road you want to take and could be flat out dangerous if you're working with machine tools.

    Having worked with one for many years, his rash, illogical behavior sounds a lot like that of a heavy drinker. I would be careful with this guy...


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