Foam and posterboard cut with a NEJE E40 diode laser on my LR3 CNC. Original pland from Flite Test in .PDF format, converted to .DXF and simplified to remove extraneous lines. DXF imported into Lightburn, with 3 kinds of cuts for the foam. Cut was supposed tontry to cut the foam (got about 50% through with a lot of melt in the foam) Score was enough to cut the top surface paper only, and Mark to jus t put dark marks on the paper.
I had originally built a needle cutter, but I never liked the cut finish it left. I could have fine-tuned it, but … lasers…
Y’know, I had intended to, but then I didn’t. I tried the wing a couple of times, but it messed up because I had settings wrong, and rhe Inhad only the 2 sheets of the correct foam board left, not quite enough with the 2 sets of wings… so I switched to this, as I thought it might be a learning experience more similar to the Zero kit that I bought. Now that I’ve built this though the short-coupled wing look more intimidating, and maybe a more mild-mannered plane will suit me better. I should still be able to build and repair it, and I can move on to the Sportster before I go to the zero anyway.
Sounds like a real blast. Probably not in the cards for me, but sure fun to watch.
I may try a needle cutter again in the future. The one I made didn’t leave clean edges at all. Guess I can put that one in the “failed” pile of things Ive built.
The undercut Im getting in white is pretty bad. It isn’t near as bad in the black. Pretty much planning to cut these plans in black next time. There is still some melt, but it cuts clean at least.
Doing the material tests, it smells bad, because there are many cuts too slow, too much power. Always ready to blow out flames. But with the dialed in settings, it isn’t bad.
For the white foam, I decided to use settings that just cut the top layer of paper, since cutting through didn’t work. Finish the cut with a knife, and it isn’t much different than transferring the pattern to the foam from printed paper, just more accurate. With the black, I can cut it with only a little melting, so an exhaust fan takes care of it easily. I’d have been cutting today, but it’s -36°outside today, so my basement is cold, and I’m not going to run the vent and make it colder.
And I never took it that way. I took it as thoroughly tounge-in-cheek, and yeah, lasers don’t leave the best edge in the foam… but that’s what you get if you buy the Flite Test kits, so it can’t be that bad.
Speaking of kits… I bought one of their kits, but figured I’m going to crash a lot while learning to fly these things again (I used to fly RC, like 30-35 years ago, and I wasn’t great at it then. ) so I wanted something that I could easily and cheaply replace parts on, so that pretty much means a scratch build, and somce I’ve been putting effort towards the laser on the LR, plus building the new machine, it seemed to be a good test use.
I built one of their Bloody Wonder airframes back in 2015. I crashed mine on the first flight, but I couldn’t remember why. I had to go back and watch the video… Looks like I just did something stupid.
It was running a material test on balsa that I burned the CoreXY laser… Well, I will work that angle again and get it working with balsa. I definitely want to be more confident in my flying skill before then. When I was flying RC 39-35 years ago, balsa was the only way to go, and I’m sure I spent more time repairing than flying for the first few years. My first flight with my trainer was maybe 45 seconds before I hit a bike rack. (Not quie right on balance. Stalled, and on recovery was low and nearly reverse direction downwind.)
On the video you said you were trying an outside loop. Looked like a reasonably successful flight up until then.
Anyway, looking forward to giving it a try, once it warms up some.
Well, I took the Tiny Trainer out for a test flight. Went well for a few minutes, then the rubber bands I used let the wing shift a bit. It started banking left and I couldn’t stop it. Before I could direct it back to me, it went into a cross-control spin.
Power pod destroyed, prop broken, one of the skewer sections is missing in the snow…
The good news is that I just need to re-attach the firewall to the new power pod, and it’ll be all ready to try again… With some new rubber bands… My last balsa R/C plane was in much worse shape. In this case, I kind of wish I’d had ailerons, but it might not have made enough difference. My R/C flying skills are as rusty as a junkyard '72 Chevy Nova.
I was looking at those, too. As something that could be replaced, it has appeal, but those still seem to be heavier than the foam planes, and need to fly faster.
This plane squeaks in under the 250g limit before it needs all kinds of regulatory requirements (Had to strip a lot of paper off of inside surfaces to get there) and I just don’t see how 3D printed could get there.