I like that String Action Guage, Blooz. I can see where that would be very informative when applied to a lot of things.

Also: measuring instuments, like rules, tapes, other devices, have a range of accuracy that may be unknown to the purchaser. Like anything there are cheap and expensive ones, poorly made and well made ones.

A way to check rulers or tape measures for accuracy is to grab any two of the same models and compare them side by side to each other: do the gradiations match up? Are the spacings equally spread out across the tape or ruler?

Another typical corner to cut by mfg's of cheap rulers and tapes is that they do not measure accurately from the "end" of the rule or tape. The measuring starts at the first gradation, and this often is not at the exact end of the rule or tape. You will find this inaccuracy in many rules and tapes.

Usually drafting rules, precision metal machine ruler used in mfg shops, and more expensive tapes, have accurate flush measuring accuracy. This is something to definitely check for if you are trying to get accurate measurements more accurate than an eigth of an inch overall linerar accuracy or a sixteenth. A lot of cheap rules and tapes will have a sixteenth of an inch of inaccuracy just at the end.

Also check longer rules against the more expensive ones for overall accuracy - do the "inch" markers line up exactly? Is the overall "foot" or other general measure, line up exactly. Check longer measuring devices like tape measures as well. Check five, ten, fifteen, twenty feet and see if they match up. Compare the inches in any given foot to see if the inches line up. Look closely at the sixteenths and see if they line up between each inch and compare the cheap and expensive tape.

Don't be surprised if the more expensive, professional type measuring tool has greater overall accuracy, as well as close accuracy within each foot and inch, as you look along the scale.

Inaccuracy of the measuring tool can cause many measuring related problems when assembling things you are building. Lots of times the innacuracies magnify each other in the designs. A little off at the beginning might end up being way off by the time you get to the end of your project.

You should always individually measure each piece as well. Avoid using the first cut piece as a template for the next and then the second one for the template for the third, etc. By the time you get done doing this a while your overall length of the final piece may differ by a significant amount from the first piece. If you need to use a template, always use the first cut piece as your template for all of the subsequent pieces.

Beware of inaccurate measuring devices, especially of end point accuracy when butting the ruler/tape up against something or measuring from the end of something. Make sure it has accurate end point accuracy or start measuring from the one inch gradation and compensate in your calculation after measuring with the device.

Hope this helps you measure more accurately.

That String Action Guage looks like it is a precision measuring device with good end point accuracy. I want one too.