Sunday, July 26, 2015

Project Mayhem 2.0

Now that Jason finished, it's time for the real fun.

Problem 1:

Cut the following joint. Page 60 in the book Jason linked.

Problem 2:

a) Using Pitagoras' theorem ("the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.") compute the raise and run of a normal hip rafter if the roof rafter pitch is 5/10.  The answer is also in the book but you need to explain how you did it.

this is the book:

b) If your layout is made with a 0.2mm line. What's your maximum precision in inches? This will tell you what makes sense to write in your plans and calculations.

Problem 3:

Design the joints to use in the following structure, and justify your choice.

Frontal view:

 And lateral view, on the left the horizontal members will rest in the stone wall

This is where the structure will go

And this is my "sketch" with my poor 3D skills.

This is the plan.

I hope you get the idea, I've never been able to use sketch up or the like, that's why didn't try it.

You need to make a diagram showing the joints to cut in the columns B1, A1, A2 and A3. Why? Because that's the way they do it in Japan according to the complete japanese joinery.

You need to draw the four surfaces of each post

And it would be great if you could also make the horizontal ones on top

My idea is that we learn how to design a somewhat larger architectural project. For Jason this will be soon useful and for the rest of us, well, you never now.

You think we can finish in a week or do we need more time? If you think I went crazy just give it a try, cannot be sooooooo difficult. And think of the advantages of it, when it's your turn you will have 3 other "designers" working for you for free. Plus, I really think we will learn a lot. What ya think? Open source world here we come.


  1. Good, practical questions Sebastian. I'm tempted to do the math in my head, in the off chance that I might get lucky and beat Steven to the punch, haha.

    Where is the structure going? Is this your new workshop, or the collectivo project that you have going on over there? The drawing aspect might take me longer than cutting the joint, although it is one that I've been wanting to try.

    Great choices!

    1. Oh yeah, I forgot to add that. We are moving to Valpo. At least for a month to try out how it goes with Roberto (the guy in the pictures). This is the place albeit with a change of focus nowadays.

      They have already the Go club working there and Roberto has his stone workshop. If the 3 guys that said wanted to take the course reply, I will be giving the course there.

      The idea is we make a "small" structure to see how we work together, if I like the place, what quality I can produce, etc. Keiran is going next week too, continue the training.

      If things go well this may be the new base for laborlimae, I got literally sick of santiago. And you can see the sea from there. Julia is also looking forward to live near the sea.

    2. That said, given the amount of research that I'll need to do for the hip calcs alone...this might take me a month, haha.

      I've wanted to go to Valparaiso for ages, Renee will be thrilled. Now we can visit! It might be a bit longer until we are ready to travel, as things are getting very hectic here.

      The stone of the shop, just beautiful!

  2. I was looking into a career in architecture last year. After a while, I realized i would be happier helping the environment, but I still love good designs and designing.

    I think you guys will beat me, my cousins are up and I am not too good at math. I don't know what a roof rafter pitch is at the moment, time to hit Google and possibly the Library.

    Good questions! I am learning a ton from you guys!

    Speaking of open source, do you ever use GIMP? It's a free open source equivalent to Photoshop, I use it occasionally.

    1. page 87 of the japanese book has the drawing Steven

      I don't use gimp, married an artist to do that :P

  3. This is excellent, I'm already thinking through the joinery for your project, but I'll need to find all the right terminology. We haven't done the lap joinery for the corner connection on top before, but I can see some interesting choices. And for the lower rail, have you seen a cogged and wedged through beam?

    Can you tell us a little more about the space for this structure? It doesn't look too big but might you have to scarf the sill beam on the long edge if its over a certain length that you can get timber?

    What about notches on the sill plate for rafters? Pole wood rafters would look really great.

    1. cogged and wedged beam? I need a picture please.

      It may large enough to need scarfing the long edge, I think it's around 6m and wood in chile is 3.2m That's one of the reasons Keiran is coming to help, wants to make one of those cool scarf joints.

      Roberto just wants the kiwi net hanging on top, it's a very dry place chile so there's almost no rain, but we may need one rafter after all...

  4. I was thinking about the drawings for the four sides of each post. In your example diagram they label them, back, front, left, right, but that doesn't make sense unless it relates directly to the plan layout with some kind of key. What about adding cardinal direction points to your plan layout, so when I am drawing the post east face is labeled N, S, E, W and we don't get in confusion about just what is left or back? Its a simple convention I've noticed most carpenters here use when talking about the walls of a building. The 'front' of a house is sometimes a matter of opinion.

    Using cardinal direction would also allow you to orient the posts to their original cardinal orientation while a tree in the ground.

  5. Also, for the hip rafter exercise, I wasn't sure what book you were referring too that had it. I'm wondering if you want hip rafter run expressed as a ratio to common rafter run, or perhaps to make up some numbers for the example common rafter?

  6. You are right, using cardinal points it's a better idea.

    I added the link to the book too. Let's stick to the 5 to 10 ratio so we make it look more like a real problem than some mathematics with x and y.

  7. I tried to get the joint cut yesterday, too much work! The sachi-sen is a very thought provoking, and the addition of the draw pin even more so. I was sawing and chopping for hours yesterday, this joint has a lot of material to remove. I'm curious if you guys have tapered sachi-sen as well as draw boring the pin? Seems like one would loosen the other if the wedges were inserted first. I'm going to end up using the sachi-sen to draw the joint tight and the square pin to lock the wedges and add to the total shear strength.

    1. Not yet... had my birthday this week and got myself a lathe and coffee machine (3 groups, lever) to repair. I hope I can cut tomorrow.