Tl;Dr: making precise miter cuts in wood takes skill that is not obvious when coming from the virtual world. Mostly because nothing is square
I like making physical things (ok, mostly food). But a lot of what I’ve made in the world is digital. When I tell my friends I’m doing wood working, those that work primarily in the digital world ask what’s hard about it?
Having just made my first-in-100-years-frame – let me tell you.
The idea is simple: cut 4 lengths of wood at 45 degree angles, and you can arrange them to make a rectangular box.
First off: the surfaces of your lengths of wood – are they square to each other? Probably not. If you purchased smooth wood (sanded 4 sides), it could be close. But the longer your lengths of wood are the less likely it is that the surfaces are square to eachother, let along consistently square across the length of the material. For example, one end might have 90 corners, and the other end might also have 90 degree corners, but if you were to transpose them against eachother, one would be at 3-to-48 degrees and the other might be at negative 5 to 48 degrees. So first: make your lengths square along the faces you want to join.
Second off: your saw is not square. The base is not flat, the fence is not at 90, and the blade angle is not at 45 degrees. Unless you check and adjust each of those. There are times you can assume things like flatness – many table saw tables are flat, some table saw fences are square. But your miter saw, your skill saw, your plastic miter box… probably not. You will need to check, then adjust your material or tools to make up for any discrepancy.
3rd off: Despite all your hard work, unless you gang-cut your miters (and even if you do), the cuts are likely inconsistent. Simple changes like the amount of pressure you apply to the material while cutting, or even internal stressses in the wood can cause the cut to be off in fairly subtle way.
4th off: You didn’t really want to cut 45 degree angles. You wanted to cut 44.9 degree angles. Sure, if the world were square, we would just cut 45. But it ain’t so you cut your angles slightly more accute, so that the exterior edges push against eachother (even if the interior edges are slightly off). This is because the exterior edges are thin and flexible. You can slightly fudge them to give a flush appearance – something you cannot do with the thick end of the joint.
5th off – your material needs to be the same length, at least in pairs (for rectangles – all sides for squares). And as silly as it sounds: measuring the correct lenght can be tricky. If your material has any thickness to it, you have to decide: measure the inside or the outside? I made a 3 dimensional frame with a ‘shadow reveal’ (a small gap between the frame and the art) which means no only do I have to add a small value to the exterior measurements, but I also have to decide where on the 3 dimensional piece to measure. Admission: I correctly measured the right distance on my slats, but measured to the wrong point on the material. And now my frame is just slightly too tall.
Keeping all these measurements correct in a 3d piece is really challenging. I glued 2 strips of material together to for a L shape. Keep the short end of the L facing towards the interior of the art turns out to be tricky (careful labeling is needed or you’ll end up with the glued side facing out which is less lovely looking that the unglued end).
Needless to say: Wisdom is the knowledge you gain from experience right after you need it. I’ve made many if not all of the mistakes. Next time I I may make fewer. We’ll see…
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