Composite Sandwich using Balsa

Build #2.

In honor of Ed S's balsa structure, the second composite will have balsa skins, rails and a horizontal balsa "springer " that will run down the middle of the board at what is referred to as the neutral axis.

I'm going to use the same basic outline as the first sandwich. So the first thing I did after cutting the outline of the 1# density core, is to layup a balsa sheet skin.

The skin is made of individual 1/16" x 4" sheets, layed out in a straight line. The general shape:

The orientation of the balsa planks can affect the flex and strength of the skin. My "design" is to allow a significant amount of flex on the bottom skin and again, I won't attach the bottom to the rails.

Since the bottom skin won't attach to the rails, I merely transferred the core outline to the balsa sheeting and then rough cut that so that it will be easier to trim after attaching to the bottom of the core.

If you look closely at the blue painters tape, you'll see that the leading edge on each piece is lifted up. What I've done is folded that over and stuck it to itself. The blue tape holds the pieces together, long enough that I can pick it up and lay it down on a piece of wetted out fiberglass. Once the fiberglass is adhered to the balsa skin, it will hold the various pieces together. I'll no longer need the blue tape and so, by having the little tab and all the orientation (leading edge) the same, I can quickly remove them and move on my way. Without that tab, pulling all the little pieces off can seem like it takes forever!

Next I can flip that whole "mess" over and lay the core on top of the wetted out glass, before sliding it into the bag to attach the bottom skin.

Currently I am contemplating hotwiring a core from the new massive blocks of foam. The one issue I have had with the boards, is that after vacuuming there is a slight springback. I'd like this project to not have that after attaching the bottom skin.