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Discussion Starter · #1 ·
Been getting back into the hobby pretty heavily recently and stumbled upon the youtuber Ramy RC. He builds giant scale composite models, mostly airliners and other passenger planes. Planes I have 0 interest in, cause they don't hoover very well lol. What's interesting is he does all of the layup directly in prepped 3D printed molds usually without even vacuum bagging. He's doing mostly hollow core stuff with traditional internal built up structures, albeit fewer since the composite skins adds tremendous strength. I was completely fascinated by the process since it really opens up the world of high end composite planes to the average Joe.

I am an average Joe, and my favorite slab of all time was my beloved Primo 60/120ax with a BCM...until Zamfir ran it over :p. So I downloaded Swany's .dxf and opened it in Fusion 360 and got to work. I designed it as a fatty, just to piss everyone off. I shortened to wing cord to make it fly like crap. And I made about 1000 other changes for no reason since the original was already perfect. Finally I named it the Full Fat Primo 60ish. For obvious reasons.

I got tired of staring at the PC, even though I still have tons of design work to finish, and I started printing the molds. My printers have been running for 24hrs straight and all I have to show for it is the mold for one side of the horizontal stab. I fully intend to fail a few times before I pull a workable piece but I figured now would be a good time to start documenting the build.

Here is the design

Font Rectangle Screenshot Line Slope

Screenshot Font Aircraft Aerospace manufacturer Aviation

Font Screenshot Line Rectangle Automotive mirror

Rectangle Font Screenshot Automotive mirror Operating system

Line Font Rectangle Screenshot Parallel
 

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You da man, AD! Following with interest :)
 

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Discussion Starter · #4 ·
Thanks Jeffe, we will see if I finish, its a pretty big undertaking but I am pretty motivated at the moment.

The top side mold is printing now. This one is out of wood fiber PLA while the first one was just generic PLA. My thoughts were it would sand a little easier and translate to less time knocking down high spots and less filler primer needed. But, this stuff is super stringy, no sure if its just how this filament is or if its just a bit wet, the package was not sealed too well when it showed up. I played with temps and it didn't go away, might need to tune retraction a bit. Either way its easy to sand down so I'll let the print finish.
Bumper Wood Automotive exterior Gas Machine
 

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Do you plan to use carbon fiber? If so what are going to use as the epoxy to glue/cure the layers together? Will you apply pressure to the parts somehow instead of vacuum bagging? Will follow, this is interesting.
 

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Discussion Starter · #7 ·
While I am still undecided on material weight, I will doing a fiber glass cloth and carbon fiber weave layup. I also plan to run strips of kevlar along the control surface lines to act as live hinges. Carbon tow will also be used to reinforce specific areas ie trailing edges, mounting points, spars, etc.

I will be using a 2 part laminating epoxy resin. My goal in this project is to do all of this without the use of a vacuum or plug. I will just lay the material into the mold and work in the resin with a roller, then leave to harden.
 

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So cool!! Great to see you posting A.D.3D (y) (y) :D :D
 
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Discussion Starter · #13 ·
Joined the mold pieces during lunch break, will start the initial sanding this evening. Hope to get the first of many coats of primer filler on too. I need these parts to have a near perfect surface finish since any imperfection will be transfered the finished part
Bumper Gas Engineering Automotive exterior Automotive tire
 

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Discussion Starter · #14 ·
I filled in the gap on each side of the mold with some bondo then did an rough sand to knock down the strings and other print imperfections. The wood fiber PLA is far easier to sand and seems to have a little better surface finish after only one go with some 400 grit. Its worth noting the wood PLA was printed with 5% infill and the generic at 10%. Those infill lines show through to the surface so that might be why the wood seems smoother, simply because there is less material/intersections behind the skin.

One concern I have is the sharp trailing edge, I think it might get lost during the upcoming sanding sessions. I may need to go back to the drawing board and redesign it to have a more blunt edge. That is a major redraw plus I would need to print new molds, so I am going to stick with it for now.

Anyways I got the first coat of filler primer sprayed and the wood definitely looks nicer. Wood PLA from here on out.
Wood Rectangle Hardwood Flooring Wood stain

Wood Rectangle Flooring Composite material Tin can

Wood Rectangle Flooring Composite material Gas

Hood Rectangle Wood Table Automotive exterior
 

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Discussion Starter · #15 ·
Also I found this video of a guy cutting bondo glazing putty with acetone and spraying it on with an airbrush. You get a thicker faster drying layer than filler primer. I think I will try that on the next set of molds
 

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Nice work AD. Glad to see another Fusion user. Currently working on a design myself.
Computer Personal computer Output device Computer monitor Gadget

Wood Rectangle Art House Tints and shades

Vehicle Aircraft Propeller Propeller-driven aircraft Propeller

Rectangle Font Triangle Parallel Electronic device

Rectangle Wood Art Font Electronic device

Computer Rectangle Font Urban design Screenshot

Computer Personal computer Rectangle Font Office equipment

Rectangle Aircraft Font Screenshot Display device

Circuit component Lighting Font Rectangle Hardware programmer
 

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That stringing on you print look like what I was getting when printing PETG I dropped my extrusion multiplier to 85 and shortened my retracts. Most all went away. Also make sure the nozzle is clean, I use a small wire brush after heating the end.
 

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Discussion Starter · #18 · (Edited)
Looks good Chris, very clean work!

Thanks Nutz, it doesn't string with fresh generic PLA or PETG. Only with this wood stuff. Did some research and evidently wood PLA is pretty notorious for picking up moisture and stringing like crazy. Drying the filament should solve the issue. I always wipe my nozzle but will definitely try to play with retraction if drying doesn't help. It's my first direct drive and the tiny retraction amount is sort of trippy, but is working great for most filament.

While that mold may not have looked very pretty initially it did sand out really nice. I've done two rounds of priming and sanding and the wood one is really starting to show it's benefits. Super smooth! The generic one is still pretty wavy but getting there.
Wood Rectangle Flooring Floor Font

Wood Audio equipment Gadget Rectangle Gas

Wood Rectangle Font Typesetting Pattern
 

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Discussion Starter · #20 ·
We can only hope it flies as bad as it looks :poop:

Still more of the same, spray primer, wet sand, rinse, repeat. The wood PLA mold is ready for wax, the other one still needs one more coat.

I am pretty happy with the results so I designed the molds for the wing and started printing since they are going to take a minimum of 80 hours. Unfortunately my brand new Ender 5 S1 (early Christmas gift from the wife) blew a hotend, so I moved over to the old printer. Its slower but has a 0.6 nozzle installed and is printing fatter/taller lines. Drying the filament did fix my stringing issue by the way.

Also set up my laser cutter and designed/printed some parts for fume extraction. This little 10w diode laser is pretty cool. Its cutting 1/4" ply with two passes, no problem. Should be able to handle most of the wood parts for this project.

Wood Rectangle Flooring Composite material Font

Gas Audio equipment Wood Electronic instrument Automotive design

Motor vehicle Hood Automotive tire Automotive exterior Gas

Hood Trunk Vehicle Motor vehicle Bumper
 
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