Three Rulers

 

 

This is a random aside. I've seen a number of ruler reviews here and there, so this is just my 2 bits on the topic. Up top are three rulers that I own. Two have been carried extensively.  

The 6" ruler is a Starrett 604RE, that I bought from McMaster. I think it was a Schwarz recommendation, but the part that grabbed me was the end graduations. I used them a LOT in setting up router bits. Because the rest of the ruler registered for a reasonable distance from the bit, I could see pretty easily, depending on the table, if there was a dip in the table, or if the insert wasn't quite flush with the surface. So, I carried it for a long while. 

The 3 incher on the left is a Starrett 603. It's an eBay find, and has a previous owner's name engraved on the other side. It, too, has end graduations, that are on the other side. It's a lot more pocket-friendly than the 6 inch, and I think I used it a couple of times for router table gauging. (If I'd had it back when I had a full time woodshop, I'd have used it a LOT more.) I actually bought it when I was a composite assembly tech at the flying car place, and it was actually more useful in that context, for an unexpected thing: Providing scale in pictures. Whenever I had an engineer who needed feedback on how well something was coming together... or wasn't, more importantly, this was a great thing to drop into the photo to provide a sense of scale. That way they had a reliable reference, in frame, that would give them a pretty reliable sense of what was going on. FOr example, in the photo at right, it was clear that the part in the background is in a parallel plane to the end of the part in the fireground, but per the end graduations, it's offset by about 1/16". And that's actually something I can use in some of my small projects these days, too. Especially if I'm trying to copy a detail of something I see 'in the wild.'

The other 3 incher is a recent find, and is an even older model, the 403. And the differences are interesting. For one, it has both capital and lower-case letters. And while it does have end graduations, they're on both sides of the ruler... but only at the 3 inch end. Lastly, it's beveled on the edge that has 1/64" graduations. I don't really need it, but it grabbed me because of the one beveled edge. And it makes a lot of sense, actually, that it's beveled on the 1/64" scale, because it eliminates a lot of errors in measuring at that scale, that would come as the result of parallax. The ruler itself is (according to my calipers) .405" thick: about 60% of the way from 1/32 to 3/64". Fussing over the exact number is pretty silly, but the point is that, lying flat, the surface with the graduations is 2.5 times higher from the surface, than the resolution of the graduations. So, you really need to be looking from directly 90 degrees over the mark, to see what the measurement is. Any side angle, and the precision of the measurement becomes suspect.

Now, my eyes are getting old, and it would require a good magnifying glass if I had to regularly measure to 64ths. (f I have to do this, I just use my phone as a magnifying glass: Turn on camera, and zoom. Take a snapshot if you really need it to hold still.) This is also ignoring the fact that, at that scale, a set of calipers or a micrometer, or feeler gauges will be a lot easier to use. BUT... as an intellectual exercise, it's one reason I like the beveled ruler better... it gets the graduations closer to the thing being measured, so the measured dimension is more precise. 

But the last odd thing that I've noticed is that, flipped over, it's easier to use with a pointy ball point pen, like the Pilot V5 Precise model. Because the bevel in that position is an overhang, the point can actually tuck in a little bit, so the point isn't pushed out from the ruler edge, and the ink doesn't wick in underneath the ruler. So, when I found a 6" on the 'bay, I picked that one up, too. (It needs a LOT of cleaning up, though.)