This layup is a sample of composite sandwich structure and is typical of the load carrying structures in the COZY. I'm using the MGS 335 epoxy system. The hardner ratio I tried today is about 50/50 H335 and H340. The epoxy pump was checked against the scale and adjusted slightly to be as accurrate as possible for the resin/hardner ratio. I"m keeping a paper log of epoxy ratio pump calibrations - I'm impressed with the accuracy you can get when you set this up exactly as per spec.
I taped a piece of plastic over the work table (abour 30 inches long). I cut 4 plies of UND ( 22in x 4in) and 4 plies of BID (22in x 4in). The BID is cut at a 45 degree fiber orientation. There was not enough BID cloth supplied with the chapter 3 kit from AC Spruce so I ended up having to cut up some of the cloth from the roll of BID purchased along with my chapter 4 kit. The new fabric cutting Wiss Scissors was a great improvement for this part of the process. I did find that the BID cloth, after being cut, lengthened ( 22+ inches) and the width decreased ( 4- inches). I was able to carefully pull the width back by hand after cutting and the dimensions of each piece were closer to the 22x4 target.
The workshop temperature was between 82 deg F and 85 deg F. In the small mixing cups, more than 2 pumps from the ratio pump is too much and it can heat up real quick - that crazy "exotherm" reaction :-)
I layed up two plies of UND, two plies of BID, then painted the foam with micro slurry and pressed it in the centre of the layup. I actually painted the bottom of the foam piece with the slurry then pressed it in to the layup and painted the foam top and sides. A better process, next time, is to paint the entire foam piece away from the layup and then introduce it to the layup. Then I layed up the other BID and UND plies. I stippled a lot with a paintbrush to work out air bubbles from the corners. I'll try trimming the layup with a coping saw or band saw after 48hrs of curing.
