So, I left it aside for a while, cause I had to quickly put together another sword.
(It is my first long sword, so I left it undocumented, mainly because I don’t like to document the experiments, but also because I was pressed for time. Perhaps I will place here it’s second version. We’ll see)
Getting back to it, my next step is gluing the layers together. One thing that I find annoying in my current layer choices (3mm, 10mm, 3mm) is that I trace the silhouette of the sword on the main later (the thick middle one), because I need to mark and cut out the slot for the core. However, when I make the foam sandwich, I need another tracing on one of the sides, so that I can actually cut the silhouette. And both tracings need to match (at least to a reasonably high extent). So… Double work with some chance of mismatch. Sloppy.
Anyways, I got the thin layers cut to the same starting width – 80mm.
Cutting it down to size. The sword will be 90cm total. The foam sheets I’m using are supposed to be 1×2m, but it turns out the short side is actually a bit more (I have not checked the long side). Irrelevant in this case.
Here I am missing a photo. As I mentioned, here I trace the dimensions of the groove on the thick layer. Here’s the tricky part:
The core is being brought up to a thickness of 10mm (by the use of electrical tape), but the sides of it are still rounded. If I cut a straight groove in the foam, the sides of the core would not fit well. The space there would be too large for my peace of mind. I want the groove to be as close as possible to the cross section of the core, so that I can really count on the glue.
So I need a cut with an internal profile. Something like this:
Cut it at an angle along each line, the blade pointing outwards, and you should get what you need. It worked surprisingly well.
(those are test cuts on a leftover piece of foam)
The middle part separates easily after the cuts.
If you are careful (and with some luck), the space left will comfortably accommodate the core.
And… a lot of glue – thin layer, thick layer with a well-covered in glue core, then another thin layer. Then fix in place with weights or clamps and wait for the glue to cure. We’ll see in a while.
What I learned:
Cutting the profiled groove: I estimated that if the groove should be a little more than 20mm at it’s widest (in the middle of the foam), then I should make my cuts a little more than 10mm apart. This needs to be a bit more… calculated. I ended up with a groove that is a bit too tight for my liking. Should have ended up with another 1-2mm. Anyways, it was not a disaster.
Cutting a profiled groove: Using the craft knife is not perfect – the body of the knife gets in the way. I’ll start using a blade only, with a marking for the depth of the cut.