Archive for November, 2009

Molds Away

Sunday, November 29th, 2009

I finished putting the molds into CAD. I used TurboCAD which is not quite as easy to use as AutoCAD. My AutoCAD license had expired and I was not going to spend $1995 to get another year. TurboCAD is less than $99 and was good enough. The molds will be cut by Knight ToolsWorks in Portland OR. Once cut I will glue the clamping strips to the molds and do any clean up that is necessary. I will also cut the holes for the clamps in the stem, I could have had the CNC machine cut them but I don’t know where I want them. I will decide when I glue up the inner stem. The next step is to build the strong back once I get the garage cleaned up.

Making A Wooden Plane

Monday, November 23rd, 2009

I took the wooden plane making class offered by the Guild of Oregon Wood- workers. The class was taught by Alexander Anderson. Each person taking the class made a plane. I made a jack plane out of Black Mesquite and I find that it works very well. I am making a scrub plane which is made out of Maple with a sole of Black Mesquite. The third plane that I am going to make is a spar plane. This plane, I think, will be the most difficult as I will be making both the body and the iron.

How to Fit the Keel to the Bottom of a Nutshell Pram

Friday, November 6th, 2009

I was recently ask how to fit the keel to the bottom of a nutshell pram. There are several ways to fit the keel. Here is the way that I did it when building my nutshell.

  1. Clamp a stick 1×2 3 feet long to the transom so that one edge is at the centerline of the boat and sticks up over the bottom by 6 inches or so.
  2. You will need a piece of plywood or cardboard about 8 inches wide by 6 feet long, this will become the pattern for the keel.
  3. Clamp the pattern to the stick so that it is on the centerline of the boat.
  4. Decide where the keel will begin and make a mark on the boat.
  5. The pattern should touch the boat at about the patterns center with equal gap at the transom and where you made the mark.
  6. Tape some blocks to the boat and the pattern so that the pattern is reasonably supported.
  7. You will need a block of wood that is taller that the gap at the beginning and end of the keel.
  8. With a pen or pencil supported on the block, mark the contour of the bottom to the pattern.
  9. Remove the pattern and cut out just shy of the line.
  10. Place the pattern back on the boat as see if you have any high or low spots.
  11. Remove material until the gaps are less than 1/8 inch. Less than a 1/16 is better.
  12. Mark the outline of the keel to the pattern and cut it out also.
  13. Use the pattern to mark the Oak and cut out the keel.
  14. Place the keel on the boat an look for any high and low spots. Again 1/8 of an inch is ok but 1/16 is better.
  15. My preference is not to use hard epoxy to attach the keel to the boat. I have used 3M 5200 but something like G-Flex would work also. You want something that has a little give to absorb shocks.
  16. Drill from inside the boat into the keel for bronze screws to hold the keel in place while the 5200 cures and the screws also give extra strength to supporting the keel.

You will may want to trim off the extra 5200 and attach brass half round to protect the keel when beaching. The whole process is fairly simple and straightforward.

Mold Design for Puddle Duck 14 Canoe

Friday, November 6th, 2009

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 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.