Week 6 - Molding and Casting

Task: design a 3D mold, machine it, and cast parts from it

Hyperbolic Paraboloid

I really like mathematical objects, and this is one of the simplist but interesting 3D form. I want to have my own cast Hyperbolic Paraboloid.


I used Grasshopper again this week to help make a geometrically accurate form. The process we're going through this week is positive wax mold to negative silicon mold to final positive hydrostone form. Since the hyperbolic paraboloid has overhangs, I had to be creative. Here's the original positive object

And my final 6 part mold (with many duplicate pieces).

To get the model to usable form, I exported as an .stl and uploaded to the fab module. Here's the stl in the fab module:

and the calculated height map:

Milling on the Modella

I had a ridiculous amount of struggle in trying to mill out my wax mold. The first time I tried I didn't let the fab module finish computing the path for the mill and it would only go ~20% of the way through.

The next night I went back and tried again, this time letting it completely compute. Unfortunately, I must've not screwed the bit in well enough and it kept falling out. The modella crashes when, after pausing to view, instead of continuing the job sending another task of moving to xyz0 (which I did to try and refit the bit in to the correct height). Once continuing, it goes on the proper path but stops the drilling motion for some reason. I tried restarting the whole job but soon the bit was falling out again. Finally, I tried one last time the next night, this time marking on the drill bit how far I put it in case it fell out (which it did). Unfortunately I was remilling over an old section of wax and the marking wasn't especially accurate for refitting the bit, so my final "completed" mold is extremely uneven and gross :(





Where to go from Here

I want to go back and hand sculpt the mold now that I don't have another opportunity to mill via the modella so I can try out casting.