It's the rainy season here in Singapore. A rainy season in a rainforest is
really rainy, so no flying or painting for the next few weeks. Given that my current project, a Stuka Stunt, is only in need of paint, I figured I'll start something new. And I'll start with a new experience for me—laser cutting. Some of our libraries here have laser cutters that are completely free to use. They do tutorials every weekend and after you do one session, it's yours to use whenever you like.
Given some limitations—namely that the bed on these cutters are only 16 inches long and I've never used these before—I decided to do a small project to learn the ropes. I found a neat .15-sized Ki-61 stunter on Outerzone and started tracing the file in Inkscape to give the laser cutter something to read.
I absolutely love the look of semi-scale stunters, especially planes like the Al Rabe Bearcat and Chris Cox's Hellcat with proper, rounded fuselages. So I made some modifications to the original plan's design. The plan called for octagonal formers that are sheeted with 1/8" balsa and sanded round. That sounds both heavy and not fun. So I redesigned the formers to be round so I can mould a thinner fuselage shell. The formers will fit square rods to ensure they're straight. The process of designing them in Inkscape and lasering them was as time-consuming as making them from scratch, but this way I can make sure I build a straight, symmetrical fuselage.
I am a messy builder. It drives both my dad and my wife crazy! Turns out that my digital working files are no different:
I mentioned earlier that the laser bed is only 16 inches long, so I started by cutting down sheets. It ended up being 17 half-sheets, ranging in width from 1.5mm (ribs, trailing edge, flaps, stab, and elevator) to 5mm (rudder and wing tips) and in weight from 4.5 lbs (rudder and wing tips) to 7.6 lbs (trailing edge). I used contest wood for everything except some structural parts.
Here's the setup at the library. It's pretty fun! I love seeing ribs and formers appear on the screen as the laser works away.
A fresh sheet of ribs.
I did some plywood as well. The doublers are 1.5mm. The half ribs are to brace the landing gear mounts. I made copies in 1/32" and 1.5mm. I don't know which I'll go with. Same for the gear doors. The bellcrank mount, nose ring, and formers are 3mm.
And here's a bunch of balsa too. I had to put masking tape over the sheets for transport as I didn't put the little breaks in the laser path to keep them in the original sheet. I was being lazy. I won't make that mistake next time.
I'm particularly proud of these: 3mm MDF patterns for making moulded blocks. I didn't want to use any of my good balsa or ply, but the library provides you with some MDF material for laser cutting. So I used that. I made notches in the formers and cutouts in the bases so that they slot perfectly into place. Just add foam and sand! I will add some bracing to the underside of the base since MDF isn't exactly diamond-strength. I think I'll also saran swap the finished bucks before molding to keep water from seeping into the MDF.
That's it for now. I guess I need to actually build the thing!
Topic: .15-Size Ki-61 Build (Read 6902 times)