Balsa/3D print hybrid builds?

[Turbojoe]

OK, so I'm absolutely bored to death right now and I'll be rambling on incoherently for a paragraph or three.......

For the last few weeks winds have been too high to fly any of my lightweight planes. To top it off our Arizona governor just put the state on total lock down last night. Just about everything including parks are closed. Can't even get a haircut. I trimmed my beard but my hair is fast approaching 1970 hippie status again. Cue the New Riders of the Purple Sage music......

I think there are a few Mountain Models aficionados here. I know for certain Joker is one. If I have my count right I've built at least 13 SwitchBack's. I've only destroyed one and sold off a few more than I wanted to. I'd have to take a head count to see how many I still have ready to fly. I've built them with retracts, as a twin, I even hung a pair of the old brushed motor GWS 75 mm ducted fans on one. I went completely nuts and built a 75% scale version too. Now I'm scratch building the easy to scratch build V-1 version and I'm making as many fuselage parts as possible with the 3D printer. I scratch built a V-1 wing many years ago and it will get no mods other than separate aileron servos. Servo mounts 3D printed of course. The fuse sides were likely cut out at the same time as the wing and I'm working with them as is but nose is lengthened 3/4".

I haven't a clue what I'm doing as far as 3D print design goes but I'm having more success than I ever expected making the fuselage bulkheads for this build. After a few failures I now have 5 of the 7 bulkheads printed and fitting perfectly. Now I need to decide on the last two motor area bulkheads. B2 and B3. I have to decide if I want to use an outrunner motor or a stick mounted geared inrunner setup. That will determine those bulkhead designs. I have many inrunner/outrunner motors/geared setups to choose from. I'm leaning toward a stick mounted geared inrunner Himax 2015 setup as I have several and they work fantastic in this plane. Bulkhead design may be tricky for me though. As soon as I have ALL of the bulkheads done to where I'm happy I'll post up pictures of the progress.

In the meantime I'd love to see what others have conjured up on their 3D printers to use in their balsa builds.

I agree with what so many are thinking, it's SO MUCH MORE work than just carving the part from balsa in mere seconds. BUT! There's a certain satisfaction of actually creating the part that you need no matter how much time you may have to invest in it.........

Joe

 

[speedbirdted]

Most I've ever done with a 3D printer on a balsa build was printing VGs to stick on the wing of my Senior Telemaster. Mostly this is because I don't have a 3D printer and the one at my old high school was limited to 2 hour print times per person so there wasn't exactly a whole lot I could do anyway. Someday though, I want to get my own printer. As for 3D printing I have no idea how to do it. Pretty much the way it worked at school was you gave the teacher an STL and the next day he gave you your print (I think it had something to do with the printer being expensive and the school understandably not wanting students to screw around with it) so I never learned any of the maintenance or troubleshooting aspects of it.

 

[rockyboy]

I've done a little bit of 3D printing for planes, but mostly models I downloaded from Thingiverse. Haven't done much 3D design work at all - but I'm really interested in watching your progress on this project

On a side note, was talking to a friend today (over Zoom) and he just got a Switchback kit from Brian back in November. He's also got another order in right now that he got a shipping notice for, and fingers crossed it'll get delivered soon!

 

[Turbojoe]

I've downloaded and printed a few things from Thingiverse and uploaded a few of my own designs there as well. I'm painfully slowly coming to grips with TinkerCad to the point that I can make complicated (for me) prototypes and tweak the final design to actually fit my needs. I still have a very long way to go but it's kinda fun. It's adding an interesting new dimension to the hobby for me. Now I have to hope my daughter doesn't decide she wants to take HER 3D printer to her house almost 40 miles away. It's been here for 15 months now. I think she may have forgotten about it......

On the SwitchBack: He'll find like just about everyone else that has ever built and flown one there's a reason most call it the original and best ever "park flyer". That's why I've built and modified so many and have a couple of NIB kits in my secret stash. It just can't be beat. So glad to hear Brian is actually shipping again.

Joe

 

[Turbojoe]

OK, so the pictures of the parts I created won't impress anyone with even a smidgen of CAD ability but I at least impressed myself. It took many prints to get some of the formers just right but I'm almost there now. Only after taking pictures of them all on the fuse side did I notice no "dome" on former F-3. Not sure why it's not there. It's a direct copy of the former from the kit. I'll re-do it and add the dome. On Former F-5 I added a lip and hole for a blind nut as I'll be modding the wing to be bolt on instead of rubber bands. Wing will also be modded for dual hidden aileron servos. I've already created and printed the servo mounts.

Instead of taking the easy route and hanging an outrunner on it I'm going old school and will use the stick mounted Himax 2015 geared setup. That means formers F-2 and F-3 determine down and right thrust so I'll probably have to make several reprints to get them just perfect.

It's coming right along but because this is a 100% scratch build using kit parts as nothing but a guide I'm adding length and width here and there to suit my needs. That means adjusting each and every part I print. It's time consuming but it's helping me get better at using TinkerCad so I think it's time well spent.

Joe

 

[rockyboy]

Those are looking great! I wonder if there are ways to design the formers that would take more advantage of the manufacturing technique - i.e. making the sides thinner to reduce weight and introducing thin buttresses or cross webbing that couldn't easily be done with balsa... all beyond me on the CAD modeling perspective, but fun to think about and watch!

 

[Turbojoe]

Weight so far is a non issue for me. All 7 formers weigh a whopping total of 20 grams. They're 3 mm thick with 10% infill. They could easily be adjusted for any need. My el cheapo scale shows a 3.7 gram servo to weigh 5.1 grams so those formers likely weigh even less than the scale reports. I'm guessing true weight of around 15 grams.

Adding webbing strength (infill) is easy. So are extra support angles. Hey, post up a picture with dimensions of what you need. I'd love to try to create an .stl file for you. If I can't do it you know there are many others here that can.

Joe

 

[Turbojoe]

Well.............I got all of the formers AND a few different motor mount firewalls designed and final 3D printed for the SwitchBack. Then I got a little bored. Like most of my projects I'll finish it "soon".

I'm guessing well over 10 years ago I did a maiden for guy and I "THINK" it was a Firebird? It was a very popular at the time pod and boom bARF. It flew great and I thought it was "cute". I kinda liked the look and It has stuck with me all this time. I refuse to fly a bARF but I've always wanted to build a pod and boom plane for some strange reason.

I took a shop inventory and I have a 3D printer, a forest of balsa, Already cut out ribs for a Mountain Models SwitchBack scratch built Sport wing. I also have a built and covered SwitchBack rudder for some reason. I've already scratch built the V-stab. I can scratch build the H-stab in no time. I've also got (and will use) a helicopter tail boom and I have electronic parts out the wazoo. That's all it took.....I've already designed and printed several 3D versions for things like pushrod guides and tail feather mounting. The hardest part was spending many hours designing, printing, reprinting and perfecting the intricacies of the fuselage boom mount and it's an absolute work of art if I do say so myself.

For "pod" inspiration I looked around at some of the planes I have. The Mountain Models Tom-E-Boy 150 jumped out and said pick me! I went to OuterZone and downloaded the old Vic Smeed Tom-E-Boy plans. I'm only using the fuselage from former F-5 forward. Main boom mount will be at former F-4. I have a box of 200 3/16" x 24 balsa sticks so I got busy a cuttin' and a gluin". The fuse sides are now done in balsa. Now I have to decide if I want to use plywood or to 3D print the formers. I know it takes longer but I love learning more about TinkerCad with each project so I may go the 3D route. I have to change filament spools so new parts will be black instead of white that everything is now.

I just started taking pictures of my progress. I won't post any up until I know everything fits together properly. Then I'll start a new thread on the build. I NEVER throw away ANYTHING R/C so because I'm not buying anything and I'm using only scrapped bits and pieces stashed away for years in deep dark places I think I'm going to do something I've never done before. I'm gonna name it...... JunkYard Dawg!

Joe