ART DU TRAIT PRATIQUE

ART DU TRAIT PRATIQUE
DE CHARPENTE

EMILE  DELATAILLE
ENTREPRENEUR DE  CHARPENTES
Professeur   de  Trait,   de  Dessin ·    et   de  Stéréotomie  à   l'Ecole  Régionale  des  
Beaux-Arts

MEMBRE  .  DE    L'ACADÉMIE   NATION ALE

1.er       Prix: Médaille d'Or  de  1.re       Classe

PREMIÈRE PARTIE

DU BOIS DROIT TRAITÉ AU NIVEAU DE DEVERS ET AUX SAUTERELLES ATTRIBUÉES AUX.COUPES DES EMPANNONS

Looking thru Emile Delataille book I noticed one of his drawings showing how to draw the claw/barbe angle on the end of the jack rafter. It's pretty easy to understand and draw.

I got this link from Patrick Moore's upcoming class on Trait De Charpente. It has  a link to download all 4 books of  Emile Delataille.

http://pdbzro.com/pdf/trait/

Using the lines drawn from the "D" points establishes the claw/barbe  angle on the jack rafter.

Draw Down Technique SketchUp Ruby Plugin

Here's a link to an updated dated version of the Roof Framing Geometry Plugin, version 1.5.

updated: Nov 14th 2013. I've added the function to draw the draw down roof surface to the ruby plugin.

Windows SketchUp Plugin

RoofFraming-v-1-5.zip

Apple - Mac SketchUp Plugin

RoofFraming-v-1-5.rbz

Windows Plugin Installation

Just unzip it in the Google SketchUp \Plugins directory.

C:\Program Files\Google\Google SketchUp 8\Plugins
or
C:\Program Files\SketchUp\SketchUp 2013\Plugins

To find the plugin folder, Open the ruby console window and and paste this into the command line in the console window.

UI.openURL("file://#{Sketchup.find_support_file("Plugins")}")

Or use the Preferences -- Install Extension  while using SketchUp.

Mac location of Plugins

/Users/mac/Library/Application Support/SketchUp 2013/SketchUp

Example of adding more rafters to the base drawing.

Add single rafter or crossing rafters like the Saint Andrews Cross.

Example of adding a rafter that is rotated from the ground line.

Example of adding a rafter that is rotated 90° from the ground line.

Example of adding the draw down roof surface to the drawing board.

Set the Units type mm.

45° plan angle example.

54° plan angle for pentagon.

60° plan angle for hexagon.

67.5° plan angle for octagon.

75° plan angle for dodecagon

Saint Andrews Cross

In this post I'll show you how to develop the geometry for the Saint Andrews Cross using the Folding Roof Surface and the Draw Down Roof Surface.  The draw down roof surface should be used in the WorldSkills Carpentry Competition or when your drawing board is not big enough to draw out the folding roof surface. Using the draw down method you can fit most task models on a 4' x 8' sheet of plywood. It will require two 4' x 8' sheets of plywood for the drawing board to use the folding roof surface method.

This task model has a hexagonal ground plan.

The Saint Andrews Cross rafters are skewed at an angle of 45° from the ground line in plan view.

Develop the Profile Rafter and the the Folding Profile Rafter. Using the radius RP-GL - T1 swing an arc to F for the location of the seat line on the roof surface. Draw a line parallel to the ground line from point T for the seat line in plan view.

Draw the hip rafter in Profile and draw the hip rafter seat line back to the ground line.

Using radius RP-GL - S swing an arc back up to point S1 that is on the level line of the profile rafter.

Draw a line from S1 parallel to the ground line. This line represents the Internal hip rafter edge development line.

Draw a line parallel to the hip rafter on the roof surface that starts at the  intersection of the Internal hip rafter edge development line at E1.

Draw the claw lines on the roof surface parallel to the hip rafter on the roof surface starting at the intersection of the hip rafter seat line and the ground line.

Draw perpendicular lines from the Saint Andrews Cross lines in plan view to the hip rafter on the roof surface.

Draw a perpendicular line from the seat line in plan view where it intersects the hip rafter seat line. This perpendicular line will intersect the seat line on the roof surface that establishes the claw line on the hip rafter on the folding roof surface. 

Draw in the width of the Saint Andrews Cross on the folding roof surface.

Place the Saint Andrews Cross Timbers on the folding roof surface and mark the miter angles and claw angles on the side of the timber. Mark the back bevel angles on the top and bottom edges of the timbers.

Drawing showing how the timbers will look after cutting on the lines.

Saint Andrews Cross timbers with the crossing bevels cut.

Hip Rafter developed from profile drawing.

Hip rafter and Saint Andrews Cross rotated into the roof surface.

Bottom view of the Saint Andrews Cross rafter claws.

Here I've moved the ground plan off to the side of the drawing for clarity to show  the draw down roof surface. To use the draw down roof surface you'll have to add two lines. One line is for the development of the claw line on the draw down roof surface and the other line is for the development of the Internal Edge of the Hip Rafter on the draw down roof surface.

Completed drawing of the draw down roof surface for the development of the Saint Andrews Cross.

Drawing showing the bottom of the roof surface with the Hip Rafters rotated into the correct position on the folding roof surface. 

The Hexagonal Ground Plan with the Saint Andrews Cross as a finished task model. It would make a great class project for 3 or 4 students.

Internal Edge of Hip Rafter On Roof Surface

There's quiet a few different ways to draw out the Internal Edge of Hip Rafter On Roof Surface, but hopefully these drawings will make it even simpler to understand. With the Internal Edge of Hip Rafter On Roof Surface dimension you'll be able to develop the miter angles of a rafter on the roof surface, using the folding or draw down technique, at any skewed angle from the plate line.

The Internal Edge of Hip Rafter On Roof Surface dimension is based on the hip rafter backing angle.
Using trigonometry
Internal Edge of Hip Rafter On Roof Surface dimension = Depth of Rafter x tan( Hip Rafter Backing Angle)

Wire frame model of a roof framing kernel with the location of the hip rafter backing angle.

Transparent view of the hip rafter backing triangle in the roof framing kernel.

Here we'll split the roof  framing kernel into two parts at the hip.

Unfold the roof framing kernel.

The basic roof framing kernel unfolded.

                         The basic roof framing kernel unfolded with the hip rafter backing triangle added.

 The basic roof framing kernel with the depth of the profile rafter drawn and the Internal Edge of Hip Rafter On Roof Surface dimension drawn at the end of the hip rafter backing triangle using the depth of the profile rafter.

On the roof surface you'll draw the center line of the hip rafter. Then you'll draw the edge of the hip rafter using the plan view location at the eave line. Then use the  Internal Edge of Hip Rafter On Roof Surface dimension  to draw the next line.

Here we have a purlin rafter that is parallel to the eave line. Mark perpendicular lines at the edge of the hip rafter and the Internal Edge of Hip Rafter On Roof Surface. Then draw the miter angle lines on the sides of the purlin rafter and the back bevel lines on the top and bottom edges of the purlin rafter.

Here we have a jack rafter that is perpendicular to the eave line. Mark perpendicular lines at the edge of the hip rafter and the Internal Edge of Hip Rafter On Roof Surface. Then draw the miter angle lines on the sides of the jack rafter and the back bevel lines on the top and bottom edges of the jack rafter.

Here we have a purlin rafter that is skewed to the eave line. Mark perpendicular lines at the edge of the hip rafter and the Internal Edge of Hip Rafter On Roof Surface. Then draw the miter angle lines on the sides of the skewed purlin rafter and the back bevel lines on the top and bottom edges of the skewed purlin rafter.

Purlin Rafter perpendicular To the Roof Surface Offset/Skewed From Plate Line