Composite Sandwich Construction Start to Finish

[Surfdad]

Out of the bag, the bottom skin is attached. I got two quick pictures out of the bag. The corecell is a light yellow and somewhat tansparent.

[Surfdad]

I use a 1/2 roundover bit in my router to trim the corecell and also shape a large portion of the rails. I leave the rails sharp from about 6" in front of the fins through the tail. I use a razor blade and sandpaper for that section...blending the two areas with sandpaper.

[Surfdad]

The bit I use has a bearing on the tip, so I just run that up on the balsa rails and the skin, glass and balsa are all trimmed up nice and neat - what the ut looks like and the trimmed board.

[Surfdad]

Back on schedule, I shaped the deck and rails this evening. I still have a little touchup, but the board is ready to have the deck bagged.

I used three basic tools. The Planer to make BIG cuts. The surfoam to roughly shape some and smooth the deeper cuts., the block plane to shape the balsa rails.

I still need to sand a bit to blend things, but it's close.

[Surfdad]

Back to it - I got distracted with a molding project and helping someone with some testing.

I attach the top corecell with 2 oz glass - it asctually weighs 2 oz. The best ratio of 'glass to resin is 1:1. That allows for the least weight and gives a strong, stiff lamination. Too much 'glass and it's flexy, too much resin and it's brittle and heavy...so...1:1. Not folks that have laminating experience are probably wondering how to spread 2 oz of epoxy! I basically just fold the cloth up and stuff it in the mixing bucket, absorbing the 2oz of epoxy.

The corecell attached to the blank with the glass and epoxy underneath.

[Surfdad]

Vacuum pulled - if you look closely the surface is smooth as glass. That's a fresh bag and THIS is the key for external lamination...start with a fresh bag.

[Surfdad]

This time of year it's pretty cold. Epoxy needs heat to cure and so I maintain that heat by covering the bag and rocker bed with an electric blanket My Walmart autoclave.

[Surfdad]

Out of the bag and ready to be trimmed. The corecell is pretty easy to work with. I'll trim it close with a single edged razor and blend it with 60 grit sandpaper.

I have to bag a d-cell skin this evening on a separate board, so it may be a few days before I get to the carbon fiber tape over the rails.

[Jason B]

I thought you dropped this project. Nice to see you didn't, it's neat to see it done! Keep going

[Surfdad]

No, I'm still working on it. This will be my board this summer, so I want it RIGHT! Just a few more steps and this one is finished, but I'm turning into a slowpoke these days.

[Jason B]

It happens...I'm going on week 2 now for installing hard wood floors in a bedroom and hallway. I could never do this for a living, my whole damn body is sore after a day of doing it! WHITE COLLAR baby

[Surfdad]

I hear you Jason - manual labor wipes me out too!

Two quick updates. The Corecell skinned board is trimmed and blended. This is an easy job. I just run a single edged razor along the rail and then use a sanding blocl to blend the skin into the rails.

The next stage is the carbon tape on the rails.

[Surfdad]

The other thing I was doing this evening was bagging the top skin on a quad square tail. This board has a single to double concave, whereas most of the other projects have a simple flat bottom. When I have been bagging the other skins, I've been using the rocker bed. This quad has a full basswood perimeter stringer. When you hotwire the rocker it will stay during a bagging, especially after laminating at least one skin and the rails.

The quad in the bag without a rockerbed.

[Surfdad]

Carbon Fiber tape bagged on the rails. The balsa tends to be bouyant, and that gives the rails a "corky" feel. The Carbon stiffens up the board as well as reducing the corkiness of the rails. This board, when finished, will weigh in around 4'ish pounds and is exceptionally bouyant. When you fall, it will typically shoot 12-15 feet in the air (and 40 feet away!!!!!)

The edge is a bit rough, but I will cover that with a pin line or a pattern that blends the carbon and corecell. It's almost impossible to do a cutlap under the bag, or at least I haven't found any good way. Things behave very differently in a vacuum.

[Surfdad]

The carbon up close.