Building a Pretty One™
From there, if you’re making a pretty one, you’ve got another step. Using your miter saw, set it to cut a 45 degree angle and make two cuts, one on each end of each board such that the length of the board doesn’t change, but both ends have a 45 degree slope inward. After cutting all 4 this way, you can set then all up on their sides and they should fit together like a box. Neat.
Use some of your painters tape to tape the corners together and see how they fit together. If you cut well, they should all fit together neatly and you’ll have minimal gaps. If any of it is rough, that’s ok, but if you have significant cracks or gaps, they may be salvageable. If it’s horrible, remove the board you think is the offender and re-cut another. Try again until it’s kinda sort not awful.
Cutting things with a miter saw is dangerous! Be careful and get someone who is comfortable doing it if you’re not.
Also, save the saw dust from when you cut all the wood! If you’re a clean freak, put it in a bowl and save it – it will come in handy to fix some some stuff in a little bit.
Ok, so you’ve got 4 sides that fit together relatively well and any cracks or gaps in the seams are pretty small. Groovy. Take your wood glue and smatter it on the angles of two of the boards. Using your finger, smooth it out so it covers the entire area and press the boards together. Grab your angle clap and clamp the top so it’s nice and tight. Then, put it on a flat surface so the side without the clamp is side-down. Press down on the sides and make sure that it’s all flat. Just make sure. Flat is good.
Once flat, check the inside corner with your speed square to make doubly sure it’s nice and square. It should be but double check. Next, very carefully use a wet rag to wipe away any excess wood glue from the outside or inside. Try to get rid of any stray wood glue as sanding it off later sucks.
Do this whole again with two more boards and then let the whole thing dry. I mean, technically most wood glue dries enough so you can unclamp everything after about 30 minutes, but wait an hour or two for good measure.
3 hours later.
Ok, time to take those clamps off. Yay two things that make right angles! They should fit together and make a box now, just like when you taped it together earlier. You may have some small gaps in the joints, but small is ok. Big is not. Fiddle until it’s flat and any gaps or cracks are not significant. You shouldn’t have any if you already checked earlier in the process.
Like before, lather some wood glue on the angles/joints, press them together and clap. Put it on a flat surface, press down, make sure everything is flat. Check with a speed square. Wipe off excess glue, tape the edges, and let it sit.
3 hours later.
Remove the claps and tape and you should have a square box and is nice and flat! Wood glue is very strong and the whole thing should be very sturdy. Check that your metal sheet can fit in the middle right now. If it’s off by a few millimeters, that’s ok. Too big, we can work with that, too small, we can file stuff down. If anything is off by more than a few millimeters, then you may have just learned something and get to try again! Yay DIY audio!