Digital calipers

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Mr Ron
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Digital calipers

Post by Mr Ron »

Ok, before you say, "I told you time and time again about the inaccuracies of digital calipers", I want to say that I agree 100% with what you say. I understand it, I get it. But one thing doesn't make sense. If digital calipers are not what they say, why are the well-known manufacturers like Mitutoyo, Starrett and Brown and Sharp selling digital calipers. They all have them 0-6" for around $150 and Mitutoyo has a 40" digital for $1800+. Are they catering to a certain group of people just to make a buck? Being precision merchants for many years with a faithful following, they must be aware to the faults of using a digital caliper where precise measurements must be had. Based on what I have heard about the inaccuracy of using a digital caliper, I question the purchasing of such tools in the future. If one must have a digital caliper, then a HF or other cheap caliper is good enough for an amateur like myself and even for a professional machinist like yourself.

We all know that China makes cheap junk, but that is because we don't demand the best from them. They will only produce what are paid for and not a penny more. If they are capable to be in the space race, they are capable of producing precision tools. I wonder what precision tools they use; are they China made, or do they use Starrett, Mitutoyo, etc. The same goes for their plant machines. I would think they are capable of producing world class machines, or do they copy the best tools from Japan, Europe or the U.S.
Mr.Ron from South Mississippi
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Harold_V
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Re: Digital calipers

Post by Harold_V »

My opinion.
The problem with calipers isn't restricted to digital. How they are applied is part of the problem of less than acceptable measurements, plus their fragile construction, of necessity, lends itself to the problem of reliable readings. There's just too many ways that improper measurements can be accomplished, so even though a measurement may be repeatable doesn't necessarily equate to one that is proper.

An additional problem with calipers is that both internal and external measurements can be taken, each of which must relate to the same display. The slightest misalignment of the jaws translates into a multiplying of the error between them, and that doesn't address the fact that the jaws may be made with an appreciable error (as to how the internal jaws relate to the external jaws). I've had that experience with a new caliper, right out of the box.

All said, I have no qualms with the idea that calipers can be made that are precise and can yield meaningful results under perfect conditions, including the proper temperature and orientation to the part being measured and exact pressure applied to the instrument when taking the reading. It's pretty easy to see why they are looked upon by people like me with considerable doubt, though, because those conditions can be difficult to produce reliably in the shop.

Do they (calipers) work? Of course they do! Would you stake your life on the resulting readings? That's a choice you have to make. I, personally, would not. I've seen how they can yield errors that are far greater than one might imagine, and I'm all too aware of the FACT that if one can't make proper measurements, achieving the goal is by chance instead of by choice. For tight tolerance work, they're simply not up to the task, regardless of what anyone says, or hopes to have you believe.

I don't have the slightest idea if the Chinese use measuring instruments made outside of their own country, but, like you, I agree that they are certainly capable of making instruments that are reliable. I also don't think that they are any different from many outside of China. They are also not exempt from the shortcomings of calipers.

It would be unusual for any industry engaged in critical work to rely on measurements accomplished strictly from the use of calipers of any description. No one is exempt from the potential errors of their measurements, which can be far beyond the tolerance range of tight tolerance work.

There is no real answer to this dilemma. Those who favor the use of calipers often offer their thoughts of support. Those who have been burned by their use do the same. I'm inclined to agree with the YouTube presentation I saw long ago whereby the video showed how to properly "adjust" a caliper, which was accomplished by holding the one in question in a large vise, then giving it a smack with a large hammer, bending it over at a 90° angle. That's how I feel about calipers unless they are used for rough measurements, much the same as one would use a ruler.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
Rich_Carlstedt
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Re: Digital calipers

Post by Rich_Carlstedt »

Just as Harold started his comment and had some good points :
My opinion
For years working in a Die shop , I tried to change the habits of my machinists, and did with most.
Before you get your knickers in a twist, we mostly used micrometers in the shop, but my "caliper" concern is :
Most everyone uses calipers incorrectly !
EVEN the manufacturers have instructions showing the wrong method application !!
"Holy Mackerel Batman, are you serious ?"
Yes !
They are the same as " Ham Fisted" mic reading ! GEEEZ , is anyone paying attention ?
If you use the thumb wheel ---you are wrong ! Yet every picture /video shows it that way
No wonder calipers get a bad wrap !
Now lets separate Caliper use from Mic Use....There is a difference AND need
How many machinists do you know that carry around 6 micrometers in their shop apron ? ( 0-1, 1-2, etc)
None, zero, nada !....Why ? :D :D
having a caliper however allows quick readings..
So what do you want ? a quick reading or a dead nuts accurate reading ?
Well, that goes with the job you are doing !
Just like a shotgun is different than a rifle for mountain sheep hunting , so too are calipers different in applications

you can read more at a recent posting on the subject
http://www.chaski.org/homemachinist/vie ... se#p454273

Rich
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Bill Shields
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Re: Digital calipers

Post by Bill Shields »

:mrgreen: but but but...if it shows 4 decimal places and it is DIGITAL -> IT HAS TO BE BETTER
Too many things going on to bother listing them.
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Harold_V
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Re: Digital calipers

Post by Harold_V »

Bill Shields wrote: Mon Sep 26, 2022 12:51 pm :mrgreen: but but but...if it shows 4 decimal places and it is DIGITAL -> IT HAS TO BE BETTER
Snicker!

H
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Bill Shields
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Re: Digital calipers

Post by Bill Shields »

I LIKE MY DIALs because they are quick to read from a distance and never need batteries...
Too many things going on to bother listing them.
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Steggy
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Re: Digital calipers

Post by Steggy »

Bill Shields wrote: Mon Sep 26, 2022 12:51 pm:mrgreen: but but but...if it shows 4 decimal places and it is DIGITAL -> IT HAS TO BE BETTER

“New technology isn’t necessarily better technology.” —Navy instructor from long ago
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Bill Shields
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Re: Digital calipers

Post by Bill Shields »

Unless you are aiming 16" naval cannons in which case...well it is moot point since nobody shoots Volkswagens off of battleships anymore.
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Harold_V
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Re: Digital calipers

Post by Harold_V »

Bill Shields wrote: Mon Sep 26, 2022 3:33 pm I LIKE MY DIALs because they are quick to read from a distance and never need batteries...
Yep! And they're much easier to read than verniers. Can't say that either is better than the other in the way of reliable readings.

H
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Steggy
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Re: Digital calipers

Post by Steggy »

Bill Shields wrote: Mon Sep 26, 2022 7:56 pm...nobody shoots Volkswagens off of battleships anymore.

Shame, isn't it? :D
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Bill Shields
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Re: Digital calipers

Post by Bill Shields »

easier to drop them from airplanes...
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seal killer
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Re: Digital calipers

Post by seal killer »

All--

I have one of those name brand calipers. I've had it for years and I've read everything that Harold and others have said about calipers. Twice.

I use mine to measure the diameter of hemp rope.

--Bill
You are what you write.
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