Composites
Machine: Shopbot
Material: Styrofoam, Flax Linen, Epoxy Resin, Fast Hardener
Software: Partworks3D
Share: Turtle Shell
Inspiration for this week's project came while Kenny displayed examples of composites he had cast. I was most impressed by his Kevlar magnified sharkskin and its fidelity to the original pattern. Travis cleverly held it behind his back like a turtle shell, so I thought I run with that idea by specifically using a turtle model. I found one online, downloaded the OBJ file, imported the mesh into Shopbot3D, and selected the 1/4 inch ball-end mill for all rough, finish, and detaching paths in Partworks3D.
When I started the Shopbot after having zeroed on the bottom left corner, the mill repositioned off the styrofoam because I accidently kept the origin as the middle of the stock in my SBP file. I used the red stop buttom - remember to twist after - and re-zeroed on the middle. An hour later the mold was complete, but remained connected to the excess stock by a very think layer of styrofoam. I traced around the mold with a chisel to release it for adding a composite layer on top.
I cut two pieces of linen into the shape of the turtle shell and added 1/8 inch fringes around the perimeter. Kenny suggested heat gun and release spray to preserve the mold after the composite hardens. In my haste working with the resin, I forgot the spray. I mixed one pump (0.8 fl oz) of resin and hardener for each side of linen. The vacuum package was formed with layers (from bottom to top) of vacuum bag, breather cloth, and perforated release film. Bag sealant tape covered half the perimeter of the vaccum bag and the other half was folded over. The vacuum tube should be localized between the breather. The shell hardened overnight.
