Saturday, September 11, 2010

Rafter plan

This is my set up at the work bench to determine the curve for the roof rafters. I don't have a substitute for the ridge of the roof but the center line should give a 10:10 angle of slope just at the apex. There are two little stubs to represent the purlins with their 4:10 rebates to house the rafters. Obviously the other side is just a mirror of this, so all parts are the same. Lots of bandsawing. I wanted to design the curve to ensure that I could cut the rafters from lengths of 2x4 without too much wastage. Each rafter will also have a little birds mouth type cut at the end to house an edging board, the whole lot will be clad in either two layers of boards or equivalent thickness of material. There is a simple scarf joint where the two sections cross the upper purlin.
There are two more beam constructions like this, but the upper short beams on the other two will be a lot simpler. I didn't have a square piece for the center, so I made a wider item into the curvy shape here. I will carve into that with the sander and whatnot, so it will be an item of interest for those who look up as they pass under the gateway roof.
I used the green masking tape on the rafter to give a clean line for my eye as there were a lot of pen scribbles from unsatisfactory lines. The tape now marks these as the originals that I can copy on to all the others. 22 of each should be in the bag before the last week of the month..

Friday, September 10, 2010

Pin pillow

I could see that the explanation might need a little more detail. This is the highest rock at the north east corner of my site. The level boards are not oriented to form a square, but the batten running left to right is square with the front two stones with its nearest edge positioned directly above the pin in the corresponding corner stone. I made a little circle of clay on the top of each stone and then tipped some molten lead in to give the little pillow slab with the anchor bolt popping up on the middle like a big drawing pin. The bolt will not act as such, it will just stop the pillar sliding off of its rock and center it on the pillow slab. The lead is molten for only a few moments, but long enough to find its level and solidify into a clean level slab.

Week on site

So, if I think back I have spent the week doing something, but when I look at the photo it doesn't seem like much. I started out back on Saturday borrowing the crane to fetch the rocks, that took most of the morning and I didn't have the energy to operate on anything else in the afternoon. On Sunday I drilled holes in the rocks to accept anchor bolts. I was going to just slot pins into them, but I realized that if I used anchors I could attach an eye nut to the threaded anchor and use that to lift the rocks into position. That worked well, but I had to weld a 16mm nut onto the 12mm eye bolt I had. The rock tilted over on the left is a spare that I will use for something else. Some people were in the habit of leaving little flower offerings by the sculpture, so perhaps a stand for some kind of vase.
After doing some rough positioning of the four pillar base rocks I discovered that one of the cedar trees would have to go, so I got permission from the land owner and chopped that down. I had to attach a chain block to it and apply some strain to pull it up the slope toward the tree with the ladder stood against it on the left. Chain blocks are not the best tool for a horizontal pull, but it worked OK. Tidying up the tree was a task I never got on to as my chainsaw decided to cease operations as soon as the tree hit the ground. I asked a neighbor to give me a hand with it the following day and he did his bit. I also had help the next day removing the bulk of the stump to position the final rock up at the top right.
The whole space frame construction here is to help me find the centers of the pillar bases. On the left and right are two sets of level boards. The extreme difference in height due to the slope meant having two levels marked out. The level on the right is a meter above the left. You can just see one tiny section of board on the right to correspond to the level on the left, which has a yellow line strung across. This line passes through the centers (or near enough) of the pins in the two front pillar rocks. Today I did my last measurement up to level to calculate the lengths of the pillars. I poured a thin slab of lead on each of the rocks to give the pillars a nice level cushion to sit on. This will also raise the outer edges of the pillar off of the rock and hopefully give them a little longer life along with the addition of copper bootees.
I took the sculpture off the site for a few days while doing all that and then popped it back to sit on some old stone drills about my shoulder height that I drove into the ground. It is still a bit wobbly, so I must devise a plan to reinforce these and provide a nice firm stand for the piece. Next week I am on to a different project nearby as a break from this. Then I will go back to working on the actual roof timber for about a week and should be on schedule to erect something on the site before the end of the month.

Friday, September 03, 2010


Another of those joinery weeks. This is the second of six joints of this type that I must make to complete the framework of the gateway.. They will tie in three beams that run front to back across the span of the roof. One of these is visible down the end. I have this pair of beams tied to the stalls aligned with their level lines true. This allows me to use a spirit level to check the planes of the joint. I think this would be an 'Ari-otoshi' among the locals. Arry who, you may ask, but it is simply a kind of drop in dovetail. The bottom of the beam is curved so that final trimming adjustment to the recess will be cut when I have the thing dropped in to draw round the beam and mate it up.
It has been quite a solid week on the roofery with lots of fiddling about with offcuts of wood to make a mock up of the rafters as templates for the cutting out I need to do on them to make them curved. Lots to do on the bandsaw when the time comes.
Having decided on the curve I am now ready to change tasks and fetch the rocks that the pillars will sit on as a foundation. I felt like I had to keep the designer hat on until I had that decision made, then I switched back to the carpenter hat for the rest of the week and will shortly turn that inside out to form the stone mason chapeau and start work on the rocks. Somehow the carpenter hat and the stonemason hat are a lot easier to swap between than the designer beret.
It was actually a lucky coincidence that helped me make the decisions on the roof design, my daughter spotted a roof truss design while on a visit to an unrelated architectural beauty. She made a sketch of what had caught her eye and that made change my plans for the better I hope.
Unfortunately I forgot all about picture taking during the mock up procedure, so pictures of the roof truss will have to wait until that is back up together next week.
The project does feel like some kind of juggling act at the moment and I would rather not have to change hats while the balls are in the air, so I need to make decisions before I can move on to some other element. The decision making on the rafters has convinced me that I will have to ask to cut down one of the cedar trees that is enjoying a little too much propinquity. I am hoping this will be OK, but if not I will just have to make the overhang of the roof at the back very truncated to compensate.
I left sharpening the chisels a little too long, but I have certainly felt the difference working with them since I did, I must remember not to be so lax in the future.