Introduction: Build a Surfboard Episode 2: Sanding
Continues the saga begun at Build a Surfboard.
The major shaping with the planer is over. Now the fine work begins, smoothing and perfecting the shape by hand sanding.
There are fluorescent sidelights along the sides of the workshop at elbow height. They make any irregularity in the board cast shadows so it's very easy to see. In this video he's sanding long lenthwise facets in the board into smooth curves. He's using a sheet of 50 grit sandpaper wrapped around a 1"x5" block of wood.
In the second video he's working on the ends of the board.
Step 1: A Faceted Gem
As the session starts the board is faceted from the strokes of the planer. The facets are a good thing. It makes it a lot easier to see and correct irregularities and asymmetries.
The rails (edges) of the board have especially clear facets.
These facets have names.
The 45 degree bevel along the bottom edge is the "undertuck".
Above that is the "template band" which is the outer edge of the board. It is the remains of the top view cut with the pullsaw.
The next facet up is the "primary bevel" at 45 degrees.
After cutting that facet he cuts a "crown bevel" which defines the sideways curvature of the deck crown.
He then flattens the peak between the crown bevel and the template band, thus making the "secondary bevel".
So, from bottom to top, here are the names of the facets:
Johnny says: "I work on those until they're good. Then I cut infinite bevels between them with the sandpaper".
Step 2: Find Asymmetries and High Spots
Johnny uses his hands like calipers, running them the length of both rails at once. Where he feels one is thicker than the other he scores it with a fingernail. A higher spot gets a deeper mark.
He tips the board up and sights down the length of the board.
Step 3: Screening the Board
When the facets are perfect each peak is flattened, subdividing each facet into two more until you have infinite facets and can barely see them.
DON'T TOUCH THE BOTTOM EDGE!!!! Leave the edge between the undertuck facet and the bottom of the board sharp for now.
Now it's time to "screen" the board. Johnny uses a sheet of drywall sanding screen. 80 grit or 120 grit. It doesn't matter which. He's been using the same piece of screen for fifteen years. You're not removing much material. He uses a pad made from a chunk of acoustic foam to press on the screen. The pad has lengthwise slashes in the bottom to make it flex more in one axis than the other. That lets it conform to the curves better.
Step 4: Surinam Cherries
Johnny has a Surinam Cherry tree in his yard. The fruits look like little red pumpkins. They're really tasty like tart cherries. Here's how you harvest them, just put some sheets under the tree and let it dump cherries on them. He says "If I don't rake them up every day It's like walking through a pile of mush. And you can't kill these things. Want some saplings? Here's a hundred of them." He points to a forest of surinam cherry tree shoots sprouting under the tree.
Step 5: Screening the Rails
Here's how you fair the rails into a perfectly rounded shape.
The screen naturally wants to assume a cylindrical shape, so it's easy to do.
DON"T MESS WITH THE BOTTOM EDGE YET!!
Step 6: The Bottom Edge
Here's how you blunt the bottom edge. It only takes a stroke or two. Don't get carried away. You can knock that edge down any time. The first photo shows how to slightly blunt it. The second photo with the screen wrapped all the way to the bottom is for a rounder edge. Look at some surfboards and windsurfers to see what kind of edges they have.
That concludes the sanding of the board.
Stay tuned for the next step, vacuum bagging woven bamboo deck panels!