Wednesday, March 25, 2015

French Timber Framing

Some really good examples of French Timber Framing can be seen on Piedefer Olivier facebook page.  These are just some of the pictures from Piedefer's facebook post. It's great when we can see the  French timber framing we're studying from books. Especially the use of the principal rafter, knee braces, purlins with batten rafters. He uses a lot of old used timbers and some of the mortise and tenon in the twisted timbers are a good study on scribing. The saint andrews cross's at some of the ridges is also interesting, but then there's the timber framed gable walls as well with mortise and tenon in the twisted gable stud timbers.

If you're interested in Timber Framing  click on the link below to visit Piedefer Olivier facebook page. (I'm not sure what photos are public)

Piedefer Olivier

Saturday, March 14, 2015

How to draw a Pentagon

I was researching the easiest way to draw a pentagon with one side known. I think this method based on Euclid Elements book 6 proposition 30 is the easiest to remember. Which is how to cut a line into a long part and a short part medially. It's basically the problem of dividing a line segment into two unequal parts, such that the whole is to the long part as the long is to the short. That doesn't make a lot of sense until you draw the pentagon using the  golden ratio  of 1.61803398875.

Golden Ratio Formula

Basically all we need to remember is the number  1.618

With one side of the pentagon known, 292mm in this example. The long part of the whole is equal to 1.618 x 292 = 472.456.

Step 1:
Draw a line equal to the known side length. Then draw a perpendicular bisector.

Step 2:
Draw two arcs from center point A & B using radius 472.456.

 Step 3:
Draw two lines intersecting the perpendicular bisector where the arcs intersect.

Step 4:
Draw two arcs from center point A & C using radius 292.

Step 5:
Draw the lines that form the pentagon.

Step 6:
Draw perpendicular bisectors on each side of the pentagon for the profile rafter runs.

Step 7:
Draw the hip rafter run lines, radius lines of the pentagon.

Sunday, February 8, 2015

American Journeyman Carpenters Examination

Normally, I would say times up hammers down, but in this case it's times up chisels down. It took me 7 hours to build Kreditloser Kamerad (Bernd Kuppers) German Journeyman Carpenters Examination task model. I scaled it down to half size and added another rafter. I might have finished in 6 hours if I didn't add the extra rafter. The full German task model would require an 8'x8' drawing board and you would have to be on your knees for most of the task model.

I was surprised that it took me 2 hours to draw out the geometry. I thought it would have only taken an hour. I can see why no one finishes the exam task model in the 6 hours. I't pretty intense keeping track of the geometry and the cuts on the timbers in a 6 hour time span. At the end of the 7 hours I was beat.

The task model exam involved an unequal pitched roof. With square rafter tails and lower claws on the jack rafter and purlin rafter. I was able to scale the exam task model down so it could be drawn out on a 4'x4' sheet of plywood.

I started at 8:24 am and finished at 3:21 pm , 7 hours. Here's a picture of the completed task model. Some of the cuts are not perfect. When you running out time it more about making the cuts on the rafters than perfection. All cuts were made with hand saws and I finished up the cuts with a chisel, then used a square block of wood with sand paper rapped around the block to clean up the cuts. No power tools were used in this task model exam.

Definitely surprised that it took 2 hours to lay out the geometry for this task model. I was wasn't stumped by any of the geometry. It just took that long to precisely draw out the geometry for the jack rafter and purlin lower claws. Again, at this point it's still a no brainier drawing out the witches cut on the hip rafter tail.

I drew out the purlin rafter lower claws lines going the wrong way. I stepped to the other side of the table and saw the mistake and drew the claw lines going the correct direction.

Lines for the witches cut on the hip rafter.

Here in this picture the base of the task model exam is assembled, but not yet screwed together.

It took an hour to cut these two gable end rafters.

Laying out the hip rafter.

Head cut and seat cut at the top of the hip rafter.

Boy, it took an hour and 25 minutes to layout and cut the hip rafter. If it was the German version it would have taken even long to use the draw knife and hand plane to edge bevel the hip rafter.

Thank God it only took about 20 minutes to layout and cut the jack rafter.

 Here's I'm cutting the lower claw on the purlin rafter.

The task model exam rafter sizes were
Rafters 1 1/4" x 2 3/8"
Exterior purlin 1 3/4" x 3 1/2"
Interior purlins and post 1 3/4" x 1 3/4"
Ridge 1 3/4" x 2 1/2"
Hip Rafter 1 3/4" x 2 5/8"