Automatic Sugru Casting Mold Script

Hi All,

I have seen a few magic instances online where folks have 3D printed molds to put Sugru (silicon rubber putty) into and then bolt together (allowing to cure overnight) in order to cast custom silicon rubber parts.

Headphone Jack Example: [sugru.com]




Custom Coupling Example: [www.thingiverse.com]
(I like how this was bolted together)






I was wondering if any of you super geniuses out in TV Land might be able to write a script that given the input of an .stl (or .scad) generates a two new .stl files which are two halves of a mold that you can bolt together with Sugru in the middle to make said rubber parts.

This would be magic on Thingiverse A relatively simple script like this would open up all kind of casting opportunities; It would be helpful for materials other than Sugru as well. Sugru molds do not need a hole to pour in fluid; this makes them simpler. Just put Sugru in the middle and mash the halves together!

I don't think this would be TOO CRAZY to pull off, but it is beyond my relatively amateur scad/cad skills right now... But I don't think this would be to difficult for the kinds of folks who browse the RepRap General forum

Considerations might include the ability to choose what axis to cut the "input STL" on; and ensuring that the end result pieces are laying smooth side down, so they can actually be printed on a reprap!

I would love to use M3 nuts and bolts to hold the mold together; maybe this could be a variable for the user to change

Who can do it?

Adam

Idolcrasher Wrote:
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> Who can do it?

You, easily.

1) If you have the openscad file which created the object you could hack that to add at the end the shapes and make a boolean operation (substraction) between the initial result and two new rectangles created to enclose the object (mould sides).

2) If only a stl is available, i dunno what openscad can do with that alone. Try freecad 0.12. Import the stl, create its shell, convert it to solid, boolean substractions, test the outputs. Something like (part module) create shape from mesh -> convert to solid. Then you can use a boolean operation between that object and the two new rectangles that you created to enclose the primary object. Export as stl then open it and -> analyze -> evaluate and repair mesh ... to check your negative mould parts for solidity or faces degeneration.
Also you could try this with some of the programs that deal with meshes directly (e.g. blender, wings, etc), but in my experience those have problems, e.g. after few operations a complex object is no longer solid and lots of mesh errors pop up. Programs which deal with objects tend to have cleaner output, because the final stl/mesh is only created at the moment of export, and hence its optimized for its shape and not for previous operations, so it does not suffer from those at all. For this reason IMHO freecad doing the boolean substraction at a "reconstructed object" level is better than pure mesh programs. Freecad also can analyze itself the final output mesh part for solidity and faces issues (analyze menu in mesh module), and is in Python and scriptable/macro-able. I think the reason why its not wider used, is just because is sort of fresh development (in terms of years lol coz its that slow), and although is still far from being fully developed, at least now it reached a stage from where it can be somewhat useful like this.