Verifying a speed square via the paper line test

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Tart

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Afternoon all

I'm a newbie woodworker wanting to make stands for my synthesisers and maybe a cajon or two if i can. I enjoy working with my hands so i decided to delve into some big-boy/girl Lego.

I recently bought a pair of Swanson speed squares and performed the lined paper test to test their squareness, after hearing how un-square a lot of tools can be. I also purchased a Faithfull FAIES6 Engineers Steel Try Square 150 mm (6 Inch) to verify it's squareness.

The lines that i drew using the speed squares were dead on so i was happy with that. However, when i used the engineering square, on the side of the speed square that i drew the lines with, i can see little bits of light peaking through when holding it up to a light. No big gaps, very slight.

Can anyone explain the logic of this and if it even matters?

Cheers

(note that i also did line test with the engineers try square and that was also spot on).
 

CStanford

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Slight, local inaccuracies along the edge don't affect total squareness of the entire edge, and/or the slivers of light you saw were less than the width of a pencil line -- very likely the case.

Proceed with the build. Your squares are apparently square enough.
 

D_W

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Agree with charlie - as much as I like to get really accurate measuring stuff when I can find it used or cheap, I can maybe thing of one thing where it really makes a difference. Fitting infills in infill planes.

Building accurately and measuring accurately aren't really the same thing. IT's better to gain some experience and see where you actually end up with missed fits - and maybe the whole of woodworking is a lot like that. Get some experience first, and then solve only the problems you identify - if the issues are real, they'll cause you enough hassle in building to solve them.

In most cases, you'll find if you jump first to solve something, it wouldn't materially affect outcome in the first place. You'll appreciate not solving problems that don't exist as you get further along.
 

Sideways

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Gaps that let plenty of light through can still be very small.
There's an interesting note somewhere on the Lie Nielsen planes website saying that checking the sole for flat with a straightedge and looking for light is far too demanding a test. Straightedge and a fine feeler gauge is their standard. You get a huge amount of light through the gap needed for even a very fine feeler gauge.
 

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