Foamy and the beam

We are starting to make some real progress on the beams now.  Weather is cooperating enough so I can mix epoxy.  Here you see several hours of work gluing the high-density inserts into the beam sides.  It was a lot of inserts (over 60) and each had to be neatly prepped, glued and adjusted to be flush.  In the foreground you see my 2-part MAS epoxy and hardener in 4-gallon containers.  This plus 4-gallons more epoxy I have in storage should be more than enough for the beams.  The 4-gallon jugs come with both valves, as shown, and hand pumps.  Although more $ per gallon, I do like them for convenience.

With the foam parts all ready for assembly, including sanding and vacuuming for good adhesion, I prepped the mold.  I had already drilled holes for screws to hold the foam parts in place from underneath, which allows me to apply the carbon fiber on top (actually on the inside).  Here you can see the mold covered in clear packaging tape to (hopefully) prevent the epoxy from sticking to the mold.  In the worst case, I have to disassemble the mold to pop the beam out, which is doable thanks to all screws being accessible.  But best case is I remove the screws holding the foam in place and the beam comes out with a little persuasion. In any case, I have the first two pieces of foam in place at either end.  Now it is a race to assemble the other pieces of foam before the epoxy kicks.

And here is the mold with all of the foam parts assembled for the forward port side beam.  I ran out of screws so I had to use every spring clamp I have to hold the aft side in place.  To assemble the foam, I wetted each edge to be bonded with straight epoxy mix, no fillers. Then I applied a bead of slightly thin putty along one edge.  The piece was pressed in place carefully to minimize epoxy squeezing out on the mold side.  Finally I installed screws from outside (underneath and on sides) to hold the piece securely while the epoxy sets.  I did have to install a couple screws on the top side to hold the curved piece in place, so I will fill those holes lightly before applying carbon fiber and epoxy.  I also lost the race with the epoxy and had to toss half of a small batch when it got too thick to use.  But I am mixing smaller batches, either 2, 4, or 6 oz at a time, so less is wasted.  I think I need to add fillets along all edges next, but I have to check the plans to make sure.  That will be the job for tomorrow.

Here is a close up view of the recessed pocket for one of the support struts.  We are looking at the inside of the beam so this recess is inside.  The bolt and nut are holding the solid GRP bolt plates in place with some precision so the folding structure all fits and aligns properly in final assembly.  Lots of little pieces are put together to construct this recess.  Hopefully the epoxy breaks lose of the tape as planned, otherwise I may have a bad day on the way.  Once I add fillets, and the epoxy cures, I will do some final sanding to round over the edges and corners.  This will help the fabric drape the form more easily, making for a stronger beam, and the beams need to be very strong.