Here's my roof framing geometric development for the
European Carpentry Competition 2012 Task
Roof Surface 1
Roof Surface 2
Roof Surface 3
Jack Rafter 1
Jack Rafter 2
While drawing the geometric development lines for this model, I realized I would have never even completed the geometric development in the 22 hours that the apprentice carpenters are allowed to draw and build the model. The European Carpentry Competition apprentices are amazing.
Here's the task plans each apprentice carpenter had to draw and build their model. This presented problems to me right from the start. I've never used a 1:10 plan scale and the metric conversion was also a problem. My first mistake was with the dimensions that use 55 . I thought it meant 10 x 5.5 = 50.5 mm. It's suppose to be 55 mm, so I had to erase a lot of the lines and start over. All of the jack rafters are rotated into the roof surface plane. So I used the size of the jack rafters, 50mm x 70mm, to draw out the rotated section of the jack rafter, based on the hip rafter backing angle, to establish the 3 to 4 lines of the jack rafter in plan view and only to erase most of those lines for clarity or the lines not being drawn correctly.
Here's the drawing of the jack rafter's section blocks that were drawn incorrectly.
Here's the drawing of the jack rafters in plan view without the section blocks that were drawn incorrectly. To make it even harder the jack rafter spacing is to the center of each jack rafter. That makes it hard to draw the jack rafters in plan view correctly. At least for me. I also, had to draw the elevation of the roof in plan view to establish where the plate line is placed.
This next drawing is the profile view of the roof rafters to the right of the plan view and the rafter rotated to establish the rabattement roof surface lines. It also has the construction lines to establish the seat line of the rafters on the rabattement roof surface.
Here's the drawing of the rabattement roof surface #1.
Here's the drawing of the rabattement roof surface #1 with Jack Rafter # 1, that is rotated into the roof surface.
Here's the drawing of the rabattement roof surface #1 with Jack Rafter # 2, that is rotated into the roof surface.
Never did see a way to establish the plumb cut on the ends of the jack rafters tails from the rabattement seat lines.
In this next drawing the theoretical hip rafter edge bevel line determines the Hip Rafter Backing line on the internal edge of the rabattement surface. That is developed from the Seat Line in Plan View and the Seat Line on Rabattement Roof Surface. If the Hip Rafter Backing line on the internal edge of the rabattement surface is not drawn correctly, you will never draw out the jack rafter bevel angles correctly.
The drawing area in the European Carpentry Competition 2012 is only about 8'x8', I would need a drawing area of about 20' x 20' to draw this out on the drawing board using the rabattement method. So, I guess the drawdown method works better for the competitions.(coucher, put-down or lay-down the roof surface)
All in all, I would have been disqualified from the European Carpentry Competition the first day.