First mold making - 3d printed buck

[thenated0g]

Yeah this was more a situation of i had a bunch of grey primer that i had purchased and decided to just use it up.

 

[Doc James Hammond]

Yeah this was more a situation of i had a bunch of grey primer that i had purchased and decided to just use it up.

Sounds a but like Microballoons - Find someone you really don't like, then give it to them.

Doc.

 

[thenated0g]

Calling it done
Will do the tail after I pull it from the mold.

 

[Wayne]

Looks very nice! Hurry up, I'm going to keep my fingers crossed for good luck!

 

[Doc James Hammond]

Calling it done
Will do the tail after I pull it from the mold.
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Plug(s) look good.

Looking at it from these perspectives, I wonder is the aspect ratio ideal? I'm sure its going to fly OK (As long as the aerofoil selction is suitable) but possibly could be a little sensitive as the MAC and the CG will be quite close together. I might have suggested maybe a teeny bit wider chord or a little sweepback?

Anyway its a fait accompli now, so like Wayne - I'm crossing my digits for a succesful moulding.

Good luck.

Doc.

 

[thenated0g]

@Doc James Hammond It's a scaled down version of my larger planks I've been building and flying. Not saying you're not correct but this is mainly to just get through the process of mold making in a miniature faster less materials way.

 

[Doc James Hammond]

@Doc James Hammond It's a scaled down version of my larger planks I've been building and flying. Not saying you're not correct but this is mainly to just get through the process of mold making in a miniature faster less materials way.

I'm absolutely sure you will learn a lot.

Doc.

 

[Wayne]

Is it done yet?

 

[thenated0g]

Lol no i have 3 projects going right now plus one waiting so going back and forth.
I need an entire day to get going on this mold so i can keep doing each layer on top of the other without sanding. waiting until it hardens but will still accept the next layer of epoxy.

 

[rcsoar4fun]

Looking good, I am curious to see the results.

I have built a bunch of molds with glass. I have shifted to epoxy and a graphite surface coat, a bit more expensive than polyester. However, better results and just easier to use.

Having said that, the last molds I made for a fuse were with Ultracal 30. Quick, cheap, easy. The best part? It doesn't stick to anything, including the plug.

Just remember to wax until you are tired of waxing, then wax some more.

 

[Doc James Hammond]

Schwing moulds I made at home.

Doc.

 

[thenated0g]

@rcsoar4fun I had considered using the ultracal stuff but i dont have anywhere locally and with shipping (its heavy!) it was cheaper to get some epoxy. Thanks for the thumbs up on the ultracal though! I will try that when i use up my epoxy.

 

[thenated0g]

3d printed some alignment keys




Also started looking on amazon and found that ultracal30 is actually not expensive and free shipping. Will have to grab some to try it out at some point.

 

[thenated0g]

I decided to make a quick first form using coroplast and ultracal 30. Almost done with it, needs some reinforcement too.

 

[Wayne]

My fingers are still crossed for you.

 

[thenated0g]

This will tell me pretty quickly if my form is going to work. Like an hour after i pour it ill know. Vs if i do the epoxy and chopmatt were talking an all day project, every 2 hours more layers, and than find out if it wont work ?? I have found a lot of threads in the composite section about guys switching to ultracal 30 as their preferred medium so i guess we will see. Ill definitely have a bunch of rags around incase it starts leaking lol. I should beable to turn around and do the other side that same day, but ill probably let it finish drying out over a week before i try putting in the vacuum bag. I think once set its got like a 6500psi pressure rating. Hardest part is figuring out how much i need to mix. 100 to 38 mix of sand to water. But how do i figure out how much is going to fill my volume i have? must be some calculators on line some where.

 

[thenated0g]

Used about 11lb dry material. Guess we will see in 30 minutes if I mixed it right

 

[thenated0g]

Came out great! Super smooth. Part actually fell out when flipping over.

 

[Hank GB Z]

Looking good Nate.

Hank

 

[Doc James Hammond]

When I used to make a lot of carbon racing propellors, I used to use a trick I learned from the Russians:

Engineering cement mixed with epoxy.

Its super hard, and if you vibrate it a bit it comes out bubble free.

Cheap and effective.

Cheers,

Doc.