Using paper to verify your PCB design from Eagle

When I design a PCB, I spend a lot of time looking at how the traces are looking, trying to find better routes, and wasting a lot of time because I made some connection wrong somewhere in the schematic… But having passed all that, the next big question is, will it fit in the box? Or maybe you just want to check if the part you designed got the right  pin placement.

Doing that the most cheap and fast way, is to just use your printer, and print the design out on a piece of paper. But doing that might not work right out of the box, here is why.

When you print your design out on the paper, put a dimension in, as large as you can get away with. My caliper goes to 150mm (and a few mm over), so that is what I went with.

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But let’s try to measure what the distance actually is…

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143.5mm! That is absolutely useless when needing to compare sizes. But luckily it is easy to fix. Divide 150 by 143.5 and we get 1.0453 (rounded the number off).

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In Eagle, on the print screen, we can then put that number into “Scale factor”, and let’s try to print it again.

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150.09mm, that is plenty close to what we need, the 0.09 is most likely me not being able to measure this properly anyways. Which is also why we want as big a distance as possible, that way the error gets multiplied, and when we then adjust that, the smaller distances will be closer to what they are set to in the package in Eagle.

All we need to do now is to cut it out, if we want to test it in the box, and here it is!

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Looks like I can easily get away with making the board a bit bigger, so the top and bottom fill will go all the way out to the edges.

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