Jim Wood's jig for building planks for the DN with proper camber
While the jig is designed for an 8 foot plank, it will handle a 10 foot plank also.
New plank in place for drilling and mounting of assembly hardware.
Note the broken plank sections on the floor.
Clamps shown to the left.
West System epoxy was used (105A resin and 209 hardener)
I used elevated temperature to post-cure the joint (100 degrees) after an over-night cure period. A tent was used coupled with thermostat controlled electric heaters.
A small error in process was made. The outer 5/16 inch x 7.5 inch planks were made up of two 3.75 inch wide planks which were edge glued to form the larger plank.
A major error was not performing the edge gluing first. I felt performing the edge gluing while gluing the outer planks to the core would ensure a good fit. But what happened was that glue was forced between the inner edges of the outer planks. Some of that adhesive was then forced through a narrow "tunnel" and off the ends of the composite structure. Some of that adhesive was trapped under the board which later necessitated some extra sanding.
|Photo shows the gluing of the first two
layers, bottom layer of 5/8 inch ash and inner core of 3/4 inch which
pine. Later the top layer of 5/16 inch ash was glued to the
top. This could have been done in one operation. But the
outer two layers consisted of two planks each for a total of four
planks, plus, the core was 1/4 inch too narrow so an additional piece
had to be glued to that board.
Due the the limited selection of ash, Dale Johnson and I could not locate a usable 7.5 inch wide ash plank. So two boards were selected and cut to one half the total width. Then the 3/4 inch planks were sliced into four 5/16 inch planks (after running through a plane).
A tab on the ash was left sticking out for temporary clamping. Later, this tab was trimmed off.