Installing handle blocking is very similar to fin blocking except you cannot drill a pilot hole to locate where it needs to go. In fact, you cannot even determine the board balance point without the board fully shaped and the weight of a fin resting on the tail. Every CNC cut frame is split in half very near the expected balance point. Simply add a few inches either side of the halfway point as a safety buffer allowing you to fine tune the balance later.
Fishbone attached to bottom skin and rails started.
Foam or wood blocking
Here is an example of typical wood blocking. This eight-inch length of wood is only 1/2″ deeper than the handle that is going to be installed. Wood blocking does not need to go all the way to the bottom of the board, as it is very strong when attached to the fishbone frame.
The extra 2″ of length on either side of centre allows you to determine the exact balance point after the board is glassed. Simply place a fin on the tail and balance the board on something. Mark the balance point and double check that you still have a minimum of 1/2″ blocking material. Here is a tutorial on how to locate your blocking using a rare earth magnet.
This 2″ foam blocking extends all the way to the bottom skin for added support. This is probably not really necessary with almost 3/4″ of wood in the centre (Fishbone seam and two gusset plates) but it would really suck to be wrong! I was given 2″ foam and since this is the lightest destiny (weighs next to nothing) I didn’t bother to reduce its size.
If you are using wooden blocking is best get the height correct when you install it. A block plane can be used to adjust the height afterwards but it is more work. With the foam blocking you can install the foam slightly oversized and use a Japanese saw to remove the excess.
After the top is installed it is important you can locate the internal blocking. I like install a bolt in the centre of my handle blocking that I can later find with a rare earth magnet.
Here I am installing a 1/4″ bolt. The piece of tape on the drill bit is a simple depth gauge so I don’t drill too far.
The temporary bolt is countersunk into the blocking with enough room for a socket. This entire area is removed later for the handle.
A piece of tape keeps glue from sealing the bolt in place and makes it easier to remove the top decking that will cover the bolt.
The bolt remains hidden in the board until the top skin is installed, the board is shaped, sanded, and laminated. With the lamination coat cure you locate the hidden bolt with the help of a rare earth magnet. No measuring required and more importantly, no chance of mistakes! We drill a hole on either side of the magnet and with a couple of strokes of a Japanese saw we remove the section of the top deck that covers the bolt.
A shop made handle jig ensures a perfect fit for the handle. The handle is installed with epoxy before the boards final gloss coat of epoxy.