The interest of calibration

[Stupid]

[Stupid]

Calibration is a standard by which all other measurements are set, and verified....from the weight of precious metals, to the time set by the sun.
In the US, this is NIST
The National Institute of Standards and Technology.
As an electronic DIY'er....I have tried to replicate the 1volt standard. It is a goal I have entertained, and enjoy.
This accuracy of data bleeds over to other elements, where other scientific results can make sense....and the scientific method is of the utmost concern.

[Stupid]

Posted by a member of the "General Radio (genrad)" yahoo group.

I took a look at the film and it evoked several feelings. Some of them were:

a) If the Navy need to show this 60 years old instruction film to their new recruits,
maybe they need to do something about the material they chose them from.

b) If measurements are so important (and I am sure they are) why keep the so
called "Imperial system"? The rest of the world (but for Burma and Belize I think)
are using the SI units for good reasons. Then their Mars probes may even work,
if they launch any! I better not dig too deep in this...

c) The film hints at the use of primary, secondary and tertiary standards. With modern

instruments, that is not necessary the way it is done any more. You buy one meter
(for the unit) and it is good enough by itself to measure up the devices to be tested.

All the best,

Carl/KQ6AX

http://tech.groups.yahoo.com/group/GenRad/message/1660

[MikeC]

I worked alongside an accredited calibration facility up until about 14 years ago - I used to internal QA check them.

As of then Primary, secondary and tertiary standards were certainly still in use - there is a lot more to calibration than electronic instruments - this place overhauled aircraft propellors, and had a lot of physical measuring deviced - micrometers, vernier callipers and the like - which were tested against slip guages - highly accurate pieces of steel. They also did hardness testing using mechanical techniques that have changed little since the 1900's - using known weights to see how large an indentation would be made in a surface. Also strength testing of materials that had undergone heat treatment, testing the effectiveness of materials at the end of their shelf lives, pressure gauges, etc.