Laminating Deck Beams (3)

Accuracy is the name of the game. Today I made the jig, or mould, for laminating all 7 deck beams of Paradox. On a piece of 16 mm Conti Board I first drew a vertical line intersected by a horizontal line; then along the horizontal line I marked off 12 x 10 mm sections to provide stations for measuring the curvature of the top of the beam. Sheet number 7 of the plan, detailing bulkhead number 2, indicates there are 6 of the above mentioned 10 mm sections either side of the central vertical line. Being careful with my measurements taken from the plan, I used a t-square and rule to mark specified points directly below each of the 10 mm sections to ascertain the shape of the uppermost surface the beam.

With the aid of a flexible batten and weights, I drew a line representing the curvature of the top of the beam; then I drew a series of tangents from the points used to determine the beam curvature. From these tangential points, I drew lines at right angles to the tangents to indicate where the lower edge of the beam would be. The length of these lines was 25 mm. It was important to draw this second curve as accurately as possible, because the shape of every beam will depend upon it.

Next I copied the curve onto another piece of Conti Board; then I used the same method as before to make yet another curve 45 mm below it. Using a jigsaw, I cut out the shape determined by both curves and the vertical sides between them; then I made an identical piece and joined them together with countersunk screws.

Before attaching them to the first cut-out, so as to exactly fit the profile of the underneath curvature of the represented deck beam, I made sure the upper curved surface was smooth and at right angles to its front facing surface. The combined thickness of both Conti Board cut-outs is 32 mm, which will provide an overlap of 7 mm for the support surface when the 25 mm plywood battens are being laminated.

Finally, I used epoxy and screws to join all 3 pieces together to form the jig for laminating my deck beams.

Tomorrow I’ll be able to make my first ‘typical’ deck beam. Matt Layden, the designer of Paradox, refers to this beam as being a ‘typical’ one, because all 7 deck beams are identical, except for the length of each, which is determined by its fore and aft station.