The Puddle Duck 14 Canoe has 7 station and 2 stem molds. Stations molds 1 and 7, 2 and 6, 3 and 5 and the two stems are identical. Station 4 is the center station of the canoe and there is only one. The patterns for the molds are from “Building a Strip Canoe” by Gil Gilpatrick. The patterns in the book were drawn in 2:1 scale and are shown half-breath for the stations and full profile for the stems. Measurements were taken from the book to the closest 1/64th to locate points on each mold so that the shape can be reproduced.
To take the measurements, a zero point on the pattern was determined in the lower left corner. At each crossing of an interval line the location was recorded. Since the pattern in the book covers two pages, the binding obscures the Y 5″ interval line. Two Y interval lines at 4 1/2 inches and 5 1/2 inches were drawn to fill in the missing data.
The points were entered into OpenOffice.org Calc to verify that the point are generally in the correct locations. Next the data will be entered into CAD and the points will be splined to make a fair curve. Some of the points may need to be adjusted to improve the curve. Once the half-breaths have been checked, they will be mirrored around the Y axis to make the full pattern. The stem pattern does not need to be mirrored because it is already a full pattern.
As part of the CAD process a description of each mold and a large cross centered at X = 0, Y = 10 will be placed on the ink layer. The cross and a description of the mold will be drawn in ink by the CNC machine. The points and lines that make up the outline of the mold will be place on the routing layer. The molds and the stem will be cut out of 3/4 (18mm) MDF by a CNC machine.