Monday, November 24, 2014

Valley Sleeper on oblique adjacent roof

This task model was challenging. Keeping track of the geometric lines to develop the valley sleeper rafter lines on the roof surface was confusing. However, I just needed to remember to draw perpendicular lines to the valley rafter in ground plan to the valley rafter on the roof surface plane to develop the correct valley sleeper plane lines. The witches cut is develop two different ways in the task model, by using two different elevation line heights.



Basic ground plan for the Valley Sleeper on oblique adjacent roof.


Drawing with the roof surface plane developed and some of the valley lines on the roof surface plane.

Zoomed in view of the valley lines, including the hidden bottom edge of the valley sleeper on the roof surface plane.

Drawing with the valley sleeper bird mouths lines developed.

Witches cut lines for the ground view of the valley sleeper rafters.


Witches cut lines for the valley sleeper rafters on the roof surface plane.


Method #two for developing the witches cut lines  and the lines for the valley rafter bevel on the roof surface at the peak of the valley sleeper rafters.



Checking my drawing with the 3D valley sleeper rafters.


Roof Planes.







Saturday, November 22, 2014

Canted Valley Rafter on Acute Angled Ground Plan

spitzwinkliges -->acute angled
verkanteter Kehlsparren auf spitzwinkligem Grund
Canted Valley Rafter on Acute Angled Ground Plan

This task model is basically the same as the Canted Valley Rafter on Rectangular Ground Plan task model. The geometry is fairly straightforward after studying the geometry for the canted valley rafter on a 90° ground plan.



Drawing the valley rafter backing triangle is not in the book, but it's my way of making sure I've drawn the canted valley rafter footprint correctly.



Here I used the German technique "Ausbaukante", expansion form the bottom edges of the profile rafters to locate the bottom edge of the canted valley rafter. In the last model I centered the canted valley rafter and the jack rafter claws protruded below the bottom edge of the canted valley rafter. By using the Ausbaukante technique in the book, the jack rafter claws do not protrude below the bottom edge of the canted valley rafter.





Witches cut plane in #d.

Witches cut angles.





Bottom of jack rafter claws flush with the bottom of the canted valley rafter.


Drawing for developing the witches cut planes on the ground plan and roof surface.



Drawing with the valley rafter shadow line for developing the cutting direction of the jack rafter lower claw.


Thursday, November 20, 2014

Shadow Lines and Witches Cut Plane

Task model

Canted Valley Rafter on Rectangular Ground Plan

Verkanteter Kehlsparren im Rechten Winkel Grund:

Lotrechten --> perpendicular
spitzwinkliges -->acute angled
verkanteter Kehlsparren auf spitzwinkligem Grund --> next task model
Canted Valley Rafter on Acute Angled Ground Plan

Interesting geometry from Bernd Kuppers book, on the Shadow Line Elevation Line, developed from the Light Source Direction, that's perpendicular to the roof surface. That develops the shadow line of the canted valley rafter and the shadow line of the outer edge of the canted valley rafter. Which in turn, develops the claw cutting line direction for the valley jack rafter lower claws. The witches planes for the canted valley rafter is also fairly easy, at this point in the book.  











The shadow line theories are similar to the French DP line. The shadow line of the valley is following the footprint of the valley rafter.

Roof Framing Geometry Proposition – Axioms  # 3:
The intersection of the DP Lines of two rafters define the line for the upper claw angle on the rafter.

Roof Framing Geometry Proposition – Axioms  # 4:
The intersection of the rafter DP Line and the hip rafter foot print line define the line for the lower claw angle on the rafter.

Roof Framing Geometry Proposition – Axioms # 9:
If the hip rafter foot print line is parallel to the jack rafter run line, then the lower claw line for the jack rafter is parallel to the jack rafter run line.

This Axiom will apply to roofs with an eave angle of 90°, with equal or unequal profile roof slope angles.

Verkanteter Gratsparren Axiom # 9






Canted Valley Rafter on Rectangular Ground Plan

I thought this task model would be easy. However, my Canted Valley Rafter on Rectangular Ground Plan
footprint does not match the drawings from the book. I'm not sure what the discrepancy is in the location of the valley rafter foot print in ground plan.









Using the geometric drawings from the book produces the correct witches cut angle  109.35613°.




Monday, November 17, 2014

Valley Rafter with single Sprocket

This task model still needs a lot of work. However, it was a lot of work just  to draw the 3D model. So I could check the geometric lines of my drawing. There's a lot going on to draw out the Valley Sprocket Rafter. I haven't even gotten to the claws on the jack rafters, but that shouldn't be hard to draw.