Author Topic: Digital Vernier is now suddenly a POS  (Read 14042 times)

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Offline saturation

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Re: Digital Vernier is now suddenly a POS
« Reply #25 on: June 19, 2012, 02:27:17 pm »
Thanks seanB and robrenz for those calibration tips.  On checking the Mitutoyo and US Starett brand calipers, one can see the huge difference in cost for those requiring highest grade tools versus the common ones found in eBay or stores.

FWIW due to interest in this thread, I found low cost Chinese vernier calipers down to 0.05mm resolution.  There are many brands.  Easier to read scale and no worries with batteries.  Don't know inevitably how accurate they are, but for general purposes, them seem better made than the run-of-the-mill calipers in the hardware store, for the same money.

http://www.ebay.com/itm/6-150MM-STAINLESS-STEEL-VERNIER-CALIPER-GAUGE-MEASURING-LAYOUT-EQUIPMENT-D52-/110884971962?pt=UK_Measuring_Tools_Levels&hash=item19d14265ba

CTC in Hong Kong specialize in measuring tools, and low cost.  They are the only one's I know who provide super sized images of their wares, which suggest they know what people need to see when looking at venier scales.
Best Wishes,

 Saturation
 

Offline icon

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Re: Digital Vernier is now suddenly a POS
« Reply #26 on: June 19, 2012, 02:42:26 pm »
Gage blocks are the general standard that you would use for calibration.

I picked these sets up for virtually nothing. They enabled me to confirm that a 6" Mitutoyo caliper I had was wrong. It caught me out a couple of times, when things I'd made didn't fit - it didn't occur to me to doubt the caliper! Turned out it was reading just slightly wrong. Very annoying.









John
« Last Edit: June 19, 2012, 02:45:36 pm by icon »
 

Offline robrenz

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Re: Digital Vernier is now suddenly a POS
« Reply #27 on: June 19, 2012, 03:09:24 pm »
That is where the terminology "Jo blocks" came from, C.E. Johansson.

Offline SeanB

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Re: Digital Vernier is now suddenly a POS
« Reply #28 on: June 19, 2012, 03:28:31 pm »
Note also the very important spec with these, they are only accurate at a specific temperature. 20C in this case.

If it is warmer then they will be slightly bigger, and the measurement will be out. The only times you really notice thermal effects, they are that precisely made.

Pity they are imperial sizes though, I would have to keep a conversion table with them if I was using them, along with a metrology cert to be sure they have not worn over the years from use.
 

Offline T4P

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Re: Digital Vernier is now suddenly a POS
« Reply #29 on: August 29, 2012, 09:37:38 am »
*Thread Revival!

Well Dave got the same one with a smashed screen in his mailbag...

Copper plate came out and in the process of placing it back i lost a grub screw :(

Buying a metal housed version next, anyone used the metal housing version before?
 

Online TheWelly888

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Re: Digital Vernier is now suddenly a POS
« Reply #30 on: August 30, 2012, 07:43:19 pm »
I had a cheap digital caliper once, it failed so I got myself one of these dial calipers which I find much easier to read than vernier calipers. The resolution of mine is 0.02mm.
You can do anything with the right attitude and a hammer.
 

Offline Rick Law

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Re: Digital Vernier is now suddenly a POS
« Reply #31 on: February 11, 2013, 10:24:20 pm »
You would be surprised ... the LSB is actually the 4th digit, it's every bit accurate

Be very carefull with that "accurate" word.  Consistent or repeatable might be more appropriate in this case. Traceable accuracy is the same principle in mechanical measurement as in electronic. :)

This is where the words PRECISE or PRECISION is useful.  Perhaps Dave means to say it is very PRECISE, but not necessarily very ACCURATE.

I expect (based on reviews I have seen) the UT61E to be more ACCURATE than my very precise $10 radioshack DMM.  With my RadioShack DMM, except for the last digit jitters, my 5% resistors is almost always reading the exactly the same value but >5% off the color code.  Precise? Yes.  Accurate? I don't know.

This is bad, I am waiting for my UT61E still enroute to me.  So, not being able to get my hands on it yet, I am loitering here to read about it.  I should get back to doing something I need doing. 

 

Offline T4P

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Re: Digital Vernier is now suddenly a POS
« Reply #32 on: February 11, 2013, 11:14:43 pm »
Ahh, for that it's not accurate but inaccurately precise  :P and perhaps why did you did you revive a half year old topic?
 

Offline Mechatrommer

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Re: Digital Vernier is now suddenly a POS
« Reply #33 on: February 12, 2013, 12:36:57 am »
semantics 101: precision tool must be "accurate and repeatable", if not then it is not precise :-\
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline Rick Law

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Re: Digital Vernier is now suddenly a POS
« Reply #34 on: February 12, 2013, 12:55:49 am »
Ahh, for that it's not accurate but inaccurately precise  :P and perhaps why did you did you revive a half year old topic?

As I said, I was expecting my UT61E which was touring San Francisco and taking its time in its eastward journey.  Not being able to get my hands on the toy, I was loitering on a forum where I can read about the UT61e.

And, as I said, I better get back to doing something I should do.
 

Offline Rick Law

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Re: Digital Vernier is now suddenly a POS
« Reply #35 on: February 13, 2013, 06:28:08 pm »
semantics 101: precision tool must be "accurate and repeatable", if not then it is not precise :-\

Silly, I know, but it interests me.  From a movie character played by Peter O’Toole: “If you don’t know the word means, you cannot possibly mean what you’ve said.”  Something like that.

This is a forum and forum is for communication, words are therefore important.  It is worth a flipping a few more bits to get some clarity here.  Since this forum is rather international, I also like to highlight the issue that we are already aware of.
 
In this case, we both could be right.  Meaning of words may change across time, across geographic regions, and across culture.  It could change even within the subculture of different disciplines.

Gay: used to mean joy and happy and now it refers to sexual preference

Chemist: In Europe, I go to a Chemist to fill my medical prescription whereas I would go to a Pharmacist in the USA.

CALORIES (all upper case for a reason):  Ask a Physicist for a calorie of heat and you get enough heat to warm a *gram* of water by one degree Celsius.  Ask a Nutritionist for a Calorie (typically upper case C) of heat and you can warm a whole *kilogram* of water by one degree C.

Metal:  Ask a Chemical scientist for a list of “metal” and ask an Astronomist for a list of “metal”, you will get a much longer list from an Astronomist.

I know in this particular case it is not change of meaning “across time”.  Searching for “precision” in Google and under “images for precision”, the “Arrow and Target” is still frequently used.  In this explanation, the closeness between arrow impact points defines “precision” whereas the closeness of impact points to bulls-eye defines “accuracy.”  So I know in this particular instance, out difference in interpretation it is likely not “across time” but “across disciplines” or “across geographic regions.”

So I do have a serious question here – what do EE folks generally define as “precision”? Since this is the EEvBlog, I must therefore defer to the EE meaning of things while here.
 
 

Offline T4P

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Re: Digital Vernier is now suddenly a POS
« Reply #36 on: February 13, 2013, 07:32:00 pm »
Precision? What's precision to me you ask.
How precise a test instrument means basically how accurate it MIGHT be
Accurate on the other hand is how close it is compared to a standard or another verified test instrument
 

Offline robrenz

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Re: Digital Vernier is now suddenly a POS
« Reply #37 on: February 13, 2013, 07:32:34 pm »
IMO  Repeatability coupled with resolution are the "precision" as in how small is the circle that all the arrows of a group fit in. Resolution comes into play in being able to define repeatability to a finer value. (higher resolution does NOT imply higher repeatability) Accuracy is how close to being concentric with the bulls eye that circle is.
« Last Edit: February 13, 2013, 07:34:14 pm by robrenz »
 

Offline Mechatrommer

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Re: Digital Vernier is now suddenly a POS
« Reply #38 on: February 14, 2013, 12:11:42 am »
Gay: used to mean joy and happy and now it refers to sexual preference
or means... happy time? we must come down to a "resolution" to avoid "repeatable" "confusion'ness". ;D
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 


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