I'm trying to figure out the best way to calculate the length for 45° trim cuts. I've seen a bunch of tutorials on cutting for 90° joints, but they never explain how to determine the actual length I need. For example, if I'm working with a square box that's 1ft by 1ft and I want to put trim around it, would I cut my pieces to 14 inches and then do the 45° cuts at the ends? I'm also thinking that I might need to add the width of the trim to my total length somehow. Anyone have tips?
3 Answers
Honestly, I just wing it! I don’t really measure much; I prefer to transfer the lengths directly onto the trim pieces and adjust as needed. Just cut a bit longer and slowly sneak up on that fit. It helps me get it just right without stressing about precise measurements.
You definitely need to add twice the width of your trim to the length. See, when you cut at a 45°, you create a triangle at the corners. The two short sides of that triangle are equal and there’s one side that corresponds to the width of the stock. So if you’re trimming each corner, you need to factor in that extra length on both sides. A good rule of thumb is to even start with the trim a bit longer, make one angle cut, then measure for the other end. It's a great way to reduce mistakes!
Remember the good old SOH-CAH-TOA rules when thinking about angles. It’s more a refresher than a detailed guide, but it can help frame your mind for right angle relationships, especially if you’re looking into doing more with angles in your woodworking!
Totally agree! Using a reference from the material rather than just relying on measurements saves you a lot of hassle.