Making a small mold for an experiment.  Planning on using expanded foam construction for

(André Roy) #1

Making a small mold for an experiment. Planning on using expanded foam construction for a new project (will make a formal project announcement shortly). Picked up Fusion 360 as my main CAD tool for this project.

(Brook Drumm) #2

Awesome! Are you going to use expanding foam? Let’s agree on the foam to use… We should invite any takers to join us in the mold making part of the effort.

(André Roy) #3

Yeah, I have no ideas what exact foam to use. Seems some research is in order. Anyone have experience with this?

(André Roy) #4

We can make public some of the geometries being worked on.

(André Roy) #5

Gonna make a trip to the local composites and plastics shop in town to see what they have for expanding foams. I read online that a wax type mold release is commonly used for expanding foam.

(Thomas Cox) #6

Use carnauba wax with PVA over top. You can get PVA from

(André Roy) #7

I’m still learning how to use Fusion 360. This is my first attempt at sharing a model so others can help experiment with mold making. I took this model and scaled it up to fit my build plate. Check out and download the mold model here:

(Brook Drumm) #8

Cool, loading the model know on my phone :wink:

I have pva :wink:

I wonder how ninjaflex works as a mold release-- when printing dual material prints, it’s hard to get PLA to stick to it

(Anthony White) #9

Foam-it 10 slow is pretty good stuff with wax coated silicon

(Anthony White) #10

“Slow” 7 minute pot life, 6x volume expansion, fast version is a couple minutes, other densities available. Think line is made by smooth-on. This an airfoil of some sort?

(Anthony White) #11

Your probably best off printing the positive if your desired part, sanding and possibly chemically smoothing it (if not an sla print) and masking a silicon mold from it to them cast the part. More steps but mold can pump out at least 30 parts instead of?

(Toby Robb) #12

@Brook_Drumm Thats an interesting thought…

(Brook Drumm) #13

I want to try both, but printing the negative sounds fun. Perhaps we could incorporate all three- positive, negative and finished parts that are neither but appropriate to use in the overall design.

(André Roy) #14

Considering the size of the plane we are thinking of producing (currently dreaming of 2.5m wingspan), and the cost of the associated hardware, I dont see a need for producing more than one unit. If/when we produce a scaled down version, accessible to most, that’s when producing multiple copies will become important.

(André Roy) #15

A large part of this project is about figuring out what works and solving problems.

(Brook Drumm) #16

I agree. We focus on the mold making to see if we can learn and provide a viable solution for larger molds. Let’s continue to clarify the vision here so we don’t frustrate each other or others with what we are doing.

I do think if a 3D printed mold helps hobbyists create a little commerce to support the habit, I mean, passion… Then that’s good

(André Roy) #17

@anthony_white2 , I picked up some Foam-it 3 and some wax mold release on the weekend to experiment with (Foam-it is a 2 part polyurethane foam). I started to print the mold, but I need to tune some of my slicer settings to get faster prints at this scale.

(Anthony White) #18

I really think you’ll have best results with a silicone rather than printed mold. Interested to see your results though!

(Toby Robb) #19

Not sure whether you can cast expanded foam, but with the correct release agent i’d say yes.

There have been lots of moulds cast using pla. Direct pla moulds poured with silicones, powdered metal and glues, epoxies etc. metal casting which you bury the pla model in a fire proof material, like sand or plaster, then burn out the pla and pour molten metals…

(André Roy) #20

@Toby_Robb , I’m aware of one fellow who successfully made foam castings. He was working on a micro scale RC Jet. He has a Youtube channel documenting his work: @Steve_Johnstone1

He was using an SLA printer though, we’ll be doing thickly layered FDM.