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First mold making - 3d printed buck

thenated0g

thenated0g

Moderator
I've been researching two-part mold making for several years now, but at some point I realized I just got to stop reading RC group threads and just get to it and I'll make whatever mistakes I make.

I also wanted to incorporate 3D printing into this to get a better shape than something I would do by hand. So there was two options now. Do you 3D print the negative molds like rammyrc or do you 3D print the positive buck and then make molds off of that. After reading some of the troubles people have had with printing out full molds and the fact they would take a ton of plastic. I decided to go the positive buck, 3D printing and sand and finish that and then make two-part molds the old fashioned way off of that piece.

Now because I knew I could make any number of mistakes and have to start over from scratch either in the 3D printing phase or on the mold making phase, I decided to take one of my designs that I knew already flew well and then size it down much smaller, 900mm wingspan, to use less plastic and materials if it's a total waste and I have to just start over from scratch.

One thing that became immediately apparent is that my ideas for plane design drastically outpace my current fusion 360 skills. In particular, I couldn't figure out how to get my wingtips how I wanted them and so once again I just said well. This is the way it's going to be. I don't want anyone thing to start hanging me up. I want to keep going so I just made the wing tips blend over into a point. I was actually pretty happy with how they turned out once I 3D printed them.
Screenshot_20220506-090511.png

PXL_20220507_165502079.MP.jpgPXL_20220508_190503234.MP.jpgPXL_20220507_232707385.MP.jpgPXL_20220507_232715704.MP.jpgPXL_20220506_160335343.MP.jpg
Using my hotwire cutter, I designed up a foam version as well and cut it out of some nice rigid foam, basically just to get access to the bottom beds to have a nice perfectly shaped working area when I'm gluing and sanding and that type of stuff.

This morning I glued all the pieces together and sanded any large overhangs and then took some thick epoxy and gave a nice coating across all the top surface. This epoxy has a set time of several hours so it'll have time to ooze out and self-level and fill in some of those grooves and low spots from the 3D printing.

To be continued.
 
Sweet!! Don't be afraid to bug @RafaelAvila for some help with Fusion. He is getting pretty good with it now.

Go for simple fiberglass molds. Don't worry about using exotic materials and this expensive mold making stuff. Keep it cheap for now, this is just experimenting at this point. Don't shoot for a lunar landing on the first mold. My first molds were just polyester resin and fiberglass scraps. Maybe 4 layers of 6 or 8 oz S-glass. CHEAP! and they were good for 20 or 30 parts. The molds were mounted to some wood and blocks to pickup the flanges. Dirt simple. No filler materials, no exotic this and that, and no scarry chemical reactions that kill everything. Later on I got into tooling gel coats etc.

Keep it simple and ignore most of the stuff the plastic companies try to sell you. LOL

A wing will be a harder first project. Most people start with something like a fuselage. Yep, they are much easier.
 
thenated0g said:
I've been researching two-part mold making for several years now, but at some point I realized I just got to stop reading RC group threads and just get to it and I'll make whatever mistakes I make.

I also wanted to incorporate 3D printing into this to get a better shape than something I would do by hand. So there was two options now. Do you 3D print the negative molds like rammyrc or do you 3D print the positive buck and then make molds off of that. After reading some of the troubles people have had with printing out full molds and the fact they would take a ton of plastic. I decided to go the positive buck, 3D printing and sand and finish that and then make two-part molds the old fashioned way off of that piece.

Now because I knew I could make any number of mistakes and have to start over from scratch either in the 3D printing phase or on the mold making phase, I decided to take one of my designs that I knew already flew well and then size it down much smaller, 900mm wingspan, to use less plastic and materials if it's a total waste and I have to just start over from scratch.

One thing that became immediately apparent is that my ideas for plane design drastically outpace my current fusion 360 skills. In particular, I couldn't figure out how to get my wingtips how I wanted them and so once again I just said well. This is the way it's going to be. I don't want anyone thing to start hanging me up. I want to keep going so I just made the wing tips blend over into a point. I was actually pretty happy with how they turned out once I 3D printed them.
View attachment 11110

View attachment 11105View attachment 11106View attachment 11107View attachment 11108View attachment 11109
Using my hotwire cutter, I designed up a foam version as well and cut it out of some nice rigid foam, basically just to get access to the bottom beds to have a nice perfectly shaped working area when I'm gluing and sanding and that type of stuff.

This morning I glued all the pieces together and sanded any large overhangs and then took some thick epoxy and gave a nice coating across all the top surface. This epoxy has a set time of several hours so it'll have time to ooze out and self-level and fill in some of those grooves and low spots from the 3D printing.

To be continued.
Click to expand...
have you try the loft tool for the wing tips?
 
Last edited:
@Wayne yes im going to use epoxy and cabosil as my tooling coats (2) and than multiple layers of some chop strand fiberglass. Possibly back filling with quickcrete or similar. Im not going to go crazy on any one step. I will sand/fill a little bit, but not going to worry about the finish too much on this first one. I like to get thru all the steps on a project and than know what i care about the next time.

for the actual parts i think im going to start off with 2x layers of 4oz S-glass, possibly with a 5x10mm strip of foam wingtip to wingtip between layers as an extra spar. 2 open molds, vacuum bag them down and than later glue them together by mating the two molds together.

@RafaelAvila yes i did a loft. I was trying to do rounded edges that also matched the leading edge as the rest of the plane. I ended up extending the trailing edge of the elevons out and than lofting that to the wingtip to get that triangle shape it has now. I need to keep learning and playing around with it.
 
Sweet. I never did try a molded wing. But fir fuselages we never knew about the backfilling and never had any issues. I liked to use a fine weave glass really close to the mold as it would sit closer into the corners and avoid bubbles decently. Then start adding thicker layers ontop of that. I almost always used woven glass instead of the chop.

Thayercraft is selling glass pretty cheap right now:
www.thayercraft.com

Fiberglass cloth from Thayercraft Inc

Save money and time buying the perfect fiberglass cloth you need with free and fast shipping from thayercraft.com
www.thayercraft.com

They sold one or two of their buildings and need to sell stuff fast. Sounds like he is letting stuff go pretty cheap. Send him an email..

S glass is probably a good choice for you (strong and stiff). I liked Volan glass for fuselages as it took curves a lot better and for me was WAY less itchy.

I'm excited to watch you master this new discipline. :)
 
Wayne said:
Hmm, interesting. I contacted him asking how much for it all. Told him you would get to pick anything you need for free if we made a deal. :)
Click to expand...

@Wayne Better hurry up and make the deal! My F350 Dually is for sale, but it might be big enough for this. With diesel at $6.50/gal, and climbing, you will have to trade some nice gliders for for this delivery! 🙃
 
lol thanks guys. I did see that sale on thayercraft. I think i have enough at the moment to play around. even some 12oz carbon. But ill go check those out. always nice to have a stock of stuff when you feel like making something.
 
Both sides have first coat of thick epoxy. Its been cold up here in lake county so going to give it a few more days to harden so it sands nice instead of gumming up.
The backlight is showing the internal 3d structure.
1652395736189.png
 
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