WEEK 12 - Composites

Assignments: design and make a 3D mold (~ft2), and produce a fiber composite part in it!

Composites!

DESIGN FILES


This week, I wasn't really inspired.. couldn't think of anything usefull to make with composites. So instead of thinking too much about it I decided to jump straight into Blender and mess around with Sverchok, Blender's parametric plugin. Generate a plane and do some maths with it. I didn't know much about Sverchok and it's usage but Blendersushi's tutorials are really good to understand the basics. So I went ahead and played with formulas.



I was happy with that shape so I pressed the "Bake" button in the viewer node to seperate the model from the nodes so I could modify it. I wanted a circular mold so I added a cylinder and applied a boolean modifier to slice my cylinder using the plane I generated.




Once the model exported I used aspire to generate the toolpath for the CNC, I used a 1/8inch ball nose end mill skipping the roughing part as I was cutting through foam. A walk in the park for the CNC. I set the base feedrate to 50mm/s and ajusted the spindle speed and feedrate live to get a decent surface finish.


Toolpath visualisation in Aspire


CNC in action!


A good hour later!

I was ready to prepare my mold. I lightly sanded the surface to smooth out some of the toolpath lines that were clearly visible.

We used Turtle Wax as a release agent applying it on the mold and on our plastic bag that would be filled with water to apply a constant pressure on the mold while it's curing.

I also cutted the mold so it could fit in the sink.. I didn't want to carry a garbage bag filled with many liters of water around..

I then mixed the epoxy resin using the ratios as mentionned on the specsheet of the product, 100:26 weight ratio for the resin:hardener or 100:25 volume ration. I used the miapoxy 100 resin and the 95 hardener, which takes around 24h to cure. Equipped with glasses and gloves, I was ready to playing.


100:26 ratio ready


Nice uniform color!

I couldn't take picture of the burlap/epoxy being applied on the mold as my hands were covered in goo. but I took a picture of the waiting... I could then go back to unboxing in my new appartment...

24h later!

Unmolding

When I was setting the water bag on top of my mold, as it was filling up with water I realized the waxed part was not exactly on the mold so I to move it slightly.. slightly dragging the burlap fiber with it.. creating a small fold in the fiber. I couldn't get it fix it earlier as I there was not enough clearance around the mold and the sink. But here's the final product.



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Even though my final part is neither perfect nor usefull, I'm quite happy with this ugly mess, the process is really fun and I can easily see how I could use this technique in my future projects!