Frame
The frame to hold the plastic sheet was constructed from some wooden planks I had kicking around the garage. Four pieces were cut to form a 24x24" square to fit perfectly onto the table; because of this, the usable area inside the frame is around 22x22". L-brackets were used to add strength to the frame, the individual planks of which were also glued and screwed together from the ends.
The L-brackets can go onto only one of the two frames (the upper frame); the underside of the upper frame comes in contact with the top side of the plastic sheet and must be flat. Likewise, the both sides of the lower frame must be as flat as possible; the top comes into contact with the underside of the plastic sheet, while the bottom part of the frame comes into contact with the table (platen).
It is crucial to the entire process that there be a tight seal between the plastic sheet and the frame, and the frame and the platen! Without a proper seal, the system will lose suction, and the pull will be ruined.
In this next photo, you can see the black rubber weather stripping lining the inside of the frame. This (or similar type of material) must line the inside of the frames, as well as the side the comes into contact with the table.
In this photo, you can also see:
1) golden release clamps (which make it very easy and quick to tightly secure the plastic sheet inside the frame);
2) metal hinges for easily opening and closing the frame;
3) metal handles, which allow one to pick the frame up from the heating box, and easily position it on the table over the mold; and,
4) my socked foot on cold cement.
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- Frame