Composite Sandwich Construction Start to Finish

[Surfdad]

Polyester is very easy and you can find water white clear for surfboards at TAP that is actually quite good. It does require the use of a respirator. The fumes are toxic even in a ventilated area.

My two favorite sources for supplies are:

http://www.fiberglasssupply.com/

http://www.foamez.com/

The folks at Foam EZ are hands down the best to work with. If you have an issue, they'll correct it without hesitation. I ordered a set of Futures Quad fins and one of the trailers was wrong. I shot them an email explaining the issue and they overnighted me the correct fin and asked if I could return the other one, if not that was ok. GREAT cutomer service. They also have complete board kits - includes everything you need to build a board, save for the tools.

Fiberglass Supply is cheaper but not as helpful. They also have a much more extensive inventory of products.

[Surfdad]

Back to the build after a night off I had that scheduled.

Starting with the core which I hotwired yesterday, I draw a centerline. Typically blanks have stringers down the middle so we don't have this issue, but our composite build requires us to do that. I use a 4' carpenters square for this.

[Surfdad]

I make a master template out of foam. Most professional shapers use masonite to store the outline shapes. I only have two basic shapes, so...I just cut and save the entire outline in 2# foam.

[Surfdad]

I center this outline on the CL I drew on the blank and then trace this on the blank.

[Surfdad]

Many instructionals and books describe using a handsaw to cut the outline, but I am lazy So I just breakout a jigsaw and cut on the line, slowly and carefully.

[Surfdad]

Typically the cut is square, but if it's a little off I straighten the cut with a surfoam.

[Surfdad]

The composite sandwich construction requires that you build from the inside out. I want to connect the rails to the fin boxes and I'll do that with a carbon tube. More over the weekend.

[Surfdad]

As I mentioned in the post above, you build from the inside out. I wanted to add a small bit to connect the rails and the fin boxes. That requires that I install that bit before the skin goes on. It's a lot like assembling a motor, the bits and pieces must go in before buttoning up the cases.

The carbon tube does a few things. One is that it stiffens up the tail, another is that it helps prevent twist-off of the board. IMO the biggest loads we have behind the boat are rail-to-rail and this longitudinal member helps minimize that twist.

The tube I am using is 1/2" OD, so I make my cut 1/2 x 1/2. In this way, when the tube is seated the top will be even with the bottom of the core. When we go to skin the blank, if we have anything standing proud, it will cause a "bump" on the skin that will need sanding.

I use a Kyobi laminate trimmer for this sort of freehand routing. The tool is light and easy to manage, plus it has a see thru plastic stand so that you can see what you are trimming.

[Surfdad]

Slot routed and the Carbon Tube trimmed and shaped along the ends to fit in the slot connecting the rails and boxes. I have measured the location of the carbon tube placement such that when I route the fin boxes in, later, the leading edge of the boxes will just nick the carbon tube. Then when I epoxy them in, I'll have a single mechanical piece.

[Surfdad]

As you would expect, the slot I routed is square and the tube, by definition is round. I fill the corners with a slurry of epoxy and microballoons. The microballoons make the epoxy thick, but also allow some ability to sand. Epoxy, when cured, is extremely hard and that makes sanding difficult. There are a bunch of products on the market, but TAP plastics is very convenient for me.

The mixture should look and feel like peanut butter, almost.

[Surfdad]

Next I slather an ample amount of the slurry in the slot, being sure to coat the sides well. Then fit the carbon tube to the slot, aligning the edges so that the cut is flush with the rail outline. Finally, using a scraper I fill in the voids so that the slurry is flush with the core. I want that smooth, without excess epoxy and also, without any voids.

[Surfdad]

The temperature here is pretty cold at night. The epoxy I used for this requires a minimum of 50 degrees to cure, but works best at 70 degrees. I have a hotbox which maintains heat anywhere up to 100 degrees F. So I toasted the board.

[Surfdad]

The next phase will be to attach the rails. We are off snowboarding today, so hopefully I will get to that tomorrow.

[dogbert]

I like it, a toasted peanut butter board

[Surfdad]

Dog you're fuuny!