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"

Wednesday, February 4, 2015

Mandala Training Task Model #1

Mandala Training Task Model #1 from the Zimmerer Nationalmannschaft website. This Mandala task model was more of a challenge for cutting the 6 compound  cuts and 6 half lap cuts precisely than the geometry for the task model. The geometry for the task model only presented one challenge and that was for determining the line for the claw.  Normally, you would use a line parallel to the hip rafter run line for developing the claw line. However, in this task model the line is parallel to the claw line in plan view. I need to research this method to see if it works on other intersecting rafters.

Here I'm checking to make sure the half lap cuts allow for the rafters to line up directly over the geometric lines of the profile rafters. I finally got the last set of rafter cut precisely. I had to score a line a 1/32 next to the lines on the rafter to use as guide for the saw. I normally just score the lines, but the compound cut on these rafters forms a 'V' on one of the corners and I kept over cutting the rafter with the hand saw. After cutting the rafter with the hand saw I would then use a chisel to remove the wood to the line and then use a sanding block to make sure the compound cut formed a 90° between the two planes of the compound cut.

The first set of  rafters being assembled. I glued the half lap joints and then I glued the claws and added one pin nail to hold the rafters in place until the glue dried. 

Six rafters assembled and in place directly over the plan view of the task model.

For the top of the task model I glued up some 1x4 poplar  and then used my router to cut the circular top.
I haven't used my Ad Quadratum & Ad Triangulum router templates for a while. So I used the Ad Triangulum router template on the bottom of the table top. The Ad Triangulum symbol is 2 equilateral triangles rotated in a circle or the base for a hexagon, which this model is based on.

Line up the circle template where you want the  Ad Triangulum symbol .

Then inset the equilateral triangle template. 

Then flip the equilateral triangle template 90°. 

Here's an image of the PDF from the Zimmerer Nationalmannschaft website. They have a link to down load the task model drawings, but I can't seem to find it again.

I scaled this task model down to a 21" tall model. There's is a 42" tall task model.

Dimension for the task model
Radius -- 7 3/32"
Height 21 1/4"

1 3/16" x 1 21/32"