Acoustic Guitar Construction

Trying to lay out a scale and being frustrated the entire morning. Should have calibrated my ruler. You can see that the yellow one is off at least 2mm. I verified the other one is correct. I kept measuring the KMG bridge-setter and it was OFF!! could not believe it. Finally realized the measuring device itself was off, not the jig.

Woodpeckers have a pretty good sale on their woodworking rulers - the 600mm is $26, which is more than I thought I'd pay for a ruler, - but I've been using that yellow one in the pic for a couple of years, just trusting that a ruler would be accurate, or why even sell it??
And I do find myself using metric for more and more things.
http://www.woodpeck.com/woodworkingrules.html

edited to change 'pretty good scale' to 'pretty good sale'. Which is a major difference in meaning..

That is alarming Dave. I have a couple of long rulers, including a yellow one. I've resisted spending the dough for a good one, but I think it would be a very good investment. I believe Incra has precision reasonably priced rulers too.
I'm putting one on my Christmas list

I should have pointed out in the picture - it's not that the 6" mark on the yellow ruler is not lined up with the 150mm mark on the yellow ruler, the problem is that the small ruler which is accurate, is lined up at 0 mm with the yellow ruler, so should line up at 150mm which it obviously doesn't.
Actually, as well, the 6" mark on the yellow ruler should line up with the 150mm on the yellow ruler, that's just sloppy production.

Hm Dave, 6" is 152,4 mm (not 150 mm) Or do I miss the point?
Herman

Holy Crap, you're absolutely right!! Thanks for that. I had never actually known that 25.4 mm figure - I'd been using 25.0.

Herman you're a peach, you're a prince among men, may your camels thrive and your pomegranates prosper, and the cedars of Lebanon be an oasis for......dang, I'm running out of metaphors....

Thank goodness that, to this point, I have not actually cut or glued any wood based on my faulty understanding of the metric system.

Thanks again dude...

It's not your fault Dave, lots of countries don't use the metric system. See? ;)
Actually, for most things other than the speed limit I still use imperial units. I can't conceive of building cabinets with millimeter measurements.