Wow! Rulers Are Not the Same! Recommend An Accurate Straight-Edge?

[Brian Evans]

I have a 24" flexible ruler that I use a lot. I use it to see what the scale length of a guitar is - that's about the measuring I do with it. I recently used it to center a neck I was installing - flexible is good when you need to bend the thing. When I carve archtops I use it all the time to judge the arch of the plate. When I lay out fretboards I use a 12" dial caliper. Accurate to .002 or so probably, so I lay out frets 1 - 11 and then start over. My straight edge - actually I have two - is actually round. I use a piece of 1/2" "Thomson Linear Bearing" rod around 15" long, it's designed for use in machines with linear bearing races, and is straight and round to less than .001" per foot. My short one is a piston pin from a car engine. I have a neat little 6" ruler, probably a Starret, in a nice leather case that seems to live by my chair. It's graduated in 32's, 64's, 50's and 100's. I can almost read the 1/64's but the 1/100's scale is a pure blur...

[Bob Gramann]

My first PEC ruler arrived yesterday. A couple of my printed rulers failed the comparison. The one I had thought was most likely to be accurate, the Ibex fret rule, was off. Dang! The little 6” ones I use most often, one a General, the other an Empire (metric), were right on (easy for that short length). Thank you to Blake for pointing this out. Fortunately, for most of the stuff I do, relative accuracy is good enough.

[Barry Daniels]

Ibex rules are notoriously inaccurate and not straight.

[Bob Hammond]

My One Rule to Rule Them All is an 8 foot Starrett layout rule that I bought an estate sale for $20. Every other tape or ruler that comes through the door is comparted to it and marked as accurate or not.