Poly carbonate digital calipers

Look,you can have .0005 resolution. it means nothing if the accuracy is .008.
end of story. The unit is just .008... posting .0005 is a trap. what's the point of having that resolution if you only have .008 accuracy.
I don't need to read it... having .0005 on accuracy of .001 is fine, you are now +- .0005, having a resolution of .0005 on a .008 means you are now +- .004 since you can't rely on the accuracy of .001 to begin with...
Yes/No?
You are correct. It is misleading advertising. Nothing new about that, whatever you are looking for. The only way to make it through the mine field is to understand well enough to know how to see through the spin...
 
Actually the accuracy in the KBC ad is +/- .008'' for a total dispersion of .016'' but that might include hysteresis. :)

It is what it is.
 
The resolution versus accuracy thing is like having a hawk's vision to look at the car in your driveway.
 
Look,you can have .0005 resolution. it means nothing if the accuracy is .008.
end of story. The unit is just .008... posting .0005 is a trap. what's the point of having that resolution if you only have .008 accuracy.
I don't need to read it... having .0005 on accuracy of .001 is fine, you are now +- .0005, having a resolution of .0005 on a .008 means you are now +- .004 since you can't rely on the accuracy of .001 to begin with...
Yes/No?

I think you are right. The problem with the KBC ad is that the word resolution actually refers to what Mitutoyo calls graduation;
http://ecatalog.mitutoyo.com/Dial-Calipers-Series-505-C1387.aspx
 
Look,you can have .0005 resolution. it means nothing if the accuracy is .008
Oh, yes, it DOES mean something; a simple pair-of-points divider has
very fine resolution, and no accuracy at all (there's no distance markings on
a divider). It's useful because it holds a setting. The inaccurate
calipers also hold a setting, and might be able to repeat it from
the numeric readout.

The metal points on a divider are a better choice for scratch-marking on
sheet metal, though, than the plastic.
 
Wouldn't a pair-of-points divider be very accurate once it was set, locked and handled consistently?
Wouldn't its resolution depend on the width of the points (i.e. how pointed they are).
 
Wouldn't a pair-of-points divider be very accurate once it was set, locked and handled consistently?
Wouldn't its resolution depend on the width of the points (i.e. how pointed they are).

I'm uncertain how 'resolution' applies; the blunt points get a touch-up every once in
a while, but it's the scratchmark they make that holds the real precision of
interest. Rounded tips still make a narrow line in the Dykem.
Resolution should be high, if you think all settings in the opening range
are distinct and spaced according to the mark width.

The reason to use dividers, is to achieve symmetry. Same distance, on
all the scribed arcs... That characteristic, symmetry, is the virtue of that
instrument.

I think the 'resolution' and 'precision' concepts relate to the measurement marks
(resolution comes from the multiplicity of marks, measured in bits
as the logarithm base two...) and to the dimension that separates the marks
('precision' is the temperature difference that separates adjacent marks on,
for instance, a thermometer).
After a thermometer calibration, there is accuracy (in degrees C or F)
up to the level of the precision, in that the absolute numeric temperature
is well-known after consulting the calibration (table or curve).

There is also accuracy (lesser accuracy) in an uncalibrated thermometer,
and (if you read the data sheet) sometimes you know that the ice point
or triple point are maximally accurate because the factory did calibrate there.
 
Oh, yes, it DOES mean something; a simple pair-of-points divider has
very fine resolution, and no accuracy at all (there's no distance markings on
a divider). It's useful because it holds a setting. The inaccurate
calipers also hold a setting, and might be able to repeat it from
the numeric readout.
Not sure I understand. A divider is not measuring to a number, it either transfers , or it divides (arc), so it is not measuring like a caliper , mic, etc. So it's an apples to orange comparison. Let's stick to measuring units.
Take a scale for instance. A scale marked in 8ths cannot measure to the 1 and 6/32nds yes I know it's 1 3/16 I'm trying to make a point. So this is the opposite of having a high resolution but low accuracy. If we determine that this scale is really accurate to the 8th. This scale is highly accurate to the 8ths but has a low resolution.

The ad in question has something measuring to 5 tenths, but the claim is we are only accurate to the side of the barn. So who cares about the 5 tenths, when this thing is measuring the barn rather than the your piece of steel.. :) I am sure you care about being close to the .001 and this measuring tool is only giving you really .01 so why would I care that it has fine graduations / resolution.. I missed the spec.. The customer wants 3.151 and I delivered 3.161... I lose. But I had a device that had .0005 resolution.. uh.. ok..

I am not making fun, but it's a serious issue. Having a high resolution, is garbage if you have no accuracy. Having accuracy is important. Because when you make parts for a friend , customer, yourself, you are basing it on a drawing, telephone call, whatever. You need to be accurate. Your .001 has to be matching their .001.. and thats all. If you have .0005 capability, but you are accurate .01 you cannot deliver.

The Harbor Fright unit has a resolution of .01, to me that unit is better than this .0005 unit. Why , because you really know what you are getting with it. That .0005 says I am more than I really am. It's a poser.
 
Back
Top