How to Mold this..

[JDM Ninja]

Hi, I 3d printed a destiny Ghost, and am molding the parts, all of the other parts are pretty straight forward to mold, but I'm trying to think of the best way to mold this part. I was hoping someone on here could help. I'm using oomoo 30

 

[ultraman]

wow that's making my head hurt trying to think about it.
seems like even if you did a 2 part mold, horizontally or vertically one half gets buried and stuck in the mold.

i wonder if there would be a way to glove mold it....or block mold it and have 3 different cuts to get it out....
man i'm gonna have to think on this one lol

 

[ultraman]

well i guess if i had to do this i would cut that in half vertically and mold the 2 halves then glue them together after casting......you may want the 3d printer to reprint 2 halves so it lines up since you will lose some material from cutting it and it may not line up right.

just a thought

 

[JDM Ninja]

Thanks for that! ill try that, but I think it may just be easier to print multiples of this part instead to make copies.

 

[cavx]

Is it possible to make the mold 3 parts instead of 2? Maybe have a rod up the middle that once removed allows that section to bend or fold to get it out?

 

[Irken Tech]

You can cover the narrow opening with a thin film (like sheet wax) and do a two part mold. After casting, the thin resin covering the opening can be easily removed and cleaned up. I think you should be able to pull the center plug of rubber out of the larger end if your silicone isn't too stiff.

 

[BrundelFly]

Do you need to make it hallow?

If so...you need a plug that has a cavity so it an be removed.

 

[robn1]

I'd make the pattern in two halves, split along the equator. And make a two part mold of each half.

 

[Scotophor]

Is it possible to make the mold 3 parts instead of 2? Maybe have a rod up the middle that once removed allows that section to bend or fold to get it out?

You can cover the narrow opening with a thin film (like sheet wax) and do a two part mold. After casting, the thin resin covering the opening can be easily removed and cleaned up. I think you should be able to pull the center plug of rubber out of the larger end if your silicone isn't too stiff.

I think combining these two methods to make a 2-part mold will work well--
Stage 1: Apply a film across the smaller of the two openings, and mold the outside/bottom half of the part (considering the end with the small opening as the "bottom"). There are a few ways this can be done, such as: A) suspend the part securely above the bottom of the mold box and simply pour the bottom half of the mold around the outside of it, or B) put the part into a box which is made so one end can be removed without destroying the box, with the large opening of the part against the removable end, then embed the part halfway in clay so that the half with the covered small opening is exposed. Pour the mold half, then when cured remove the end of the box and clean out the clay before molding the other half.
Stage 2: After the bottom half of the mold has cured, suspend a cylindrical plug somewhat smaller in diameter than the larger opening, inside the part as shown below, being sure it doesn't touch the part, then apply mold release and mold the top half of the part including the outside and inside. If the plug is a material that might get stuck to the mold, apply mold release to its bottom end before suspending it in the part.

When the mold has cured, you first remove the plug and it will no longer be needed. Then the top part of the 2-part mold will be easy to remove, since there is now space for the interior portion to be squished into so it can easily fit through the opening in the part. As Irken Tech wrote, your castings from this 2-part mold will probably have a resin skin across the small opening where the film was separating the mold parts, but this will easily be trimmed away.

 

[CB2001]

What about a one piece mold? Basically put the piece in a mold box with the curve going down, pour the mold. Then flip it over, pull it out, so that way when you go to pour the resin, it flows down the curve? I'm just tossing that idea out there as a possibility. What do I know. I haven't even molded anything myself yet.

 

[Anders]

+1 collapsible plug, 2 part mold is the best way, and should be seamless as the seam line will be on a raw edge

 

[JPH]

have you thought about using a doorknob or something similar?

 

[teragon]

What about filling it with clay, make a standard 2 parts mold and then just rotocast the resin inside ? You'd have a hollow piece once you cut the two openings ?

 

[CB2001]

Hey, Tested (a YouTube channel ran by Jamie and Adam from the Mythbusters, Adam being a long time member of the RPF), has recently posted this tutorial and breaks down the types of molding that can be done while showing a tutorial for a two-part mold. They actually explain that the molds should be determined by the complexity of the object being molded. Though I still think maybe a one piece mold would be good, I'm sure I could very well be wrong.

 

[Kevin Gossett]

With a one piece mold, you wouldn't be able to get the piece out because of the shape. That's why a collapsible plug is necessary