Tuesday, October 29, 2013

European Task Model #1

Tony McGartland from South West College, Omagh. N.Ireland, who helps train the UK/Ireland apprentice carpenters for the WorldSkills Carpentry Competition sent me a couple of the European Task Models. These task models look like fun projects. This first task model has the typical irregular hip rafter on an eave angle of 105° with jack rafter with claws. There's also one rafter plumb to the earth and skewed from the plate line.

One thing that's confusing in the task model drawing is the color of the orange - brown rafter on the right side of the drawing. I don't think it should have been the color orange-brown like the hip rafter, because it's just  a rafter that's plumb to the earth and skewed from the plate line. It's a Schräge Sparren and has a top bevel edge, but it's not a hip rafter in this drawing. Hip rafters have a dihedral angle triangle and Schräge Sparren  do not. It's similar to what we call a gable end prow rafter. But the Schräge Sparren top edge is beveled. 

Plan View of the Task Model

Rafter Profiles developed from Plan View and the Jack Rafter Claw Angles developed from the prism plane geometry.

The task model wasn't clear on the tail slope angle, unless you speak Danish, so I used a tail slope angle 105° to develop the Hexenschnitt -- The Witches Cut on the hip rafter and the Schräge Sparren.

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