Friday, August 27, 2010


The roof project requires a few timbers longer than I have on hand, so I have to make four scarf joints like this one.
These are about the most complex joints I get into. The end on the left shows how a little nose of timber grips into a recess in the corresponding part. The key to the joint is the diagonal edge to the two flats of the scarf surfaces. The joint starts off slack, but as you drive the two sides together the diagonal center forces the two noses into the mating part and makes for a very tight bond. Set squares in japan are commonly 15mm wide, so the width of the square can be used to draw the nose and recess as well as the two mating flats of the scarf.
The lower picture shows the joint when driven home as well as a full scale drawing I did to plan it out for this size of timber. These pieces will hold up the rafters and I will aim to get the joints between two rafters. The joint can be oriented either way I think, but if you want to assemble it on site orient it like this so that it can be driven in on top of any tenons the timber mates with. This is also a bit of a show off if the roof timbers are visible from below. In the upper picture the piece on the right would have to be laid first, then the left part driven home on top of it. I have three mortises to cut in this piece now, then I will cut off the excess timber and use that for struts in the roof.

Sunday, August 22, 2010

Bob a Job

Something of an invasion of territory. I took a week off from the roof project. On monday I went and fetched more cypress logs from the dam stockyard and spent the rest of the week up to Friday preparing these and other timbers for a project to remove an obstructive beam from my wife's work area. The cut off ends of the beam are visible at left and right here about half way up the new pillars. To enter the space one used to have to limbo under the beam, the urge to duck still overcomes us at the portal, but there is now no need to bow on entry. I timed the construction for a three day spell in which the office would be empty and just managed to get everything back in rough order ready for a reorganization of the chaos with the new layout. This is the area that featured back in October 2006. Actually the drawing from the 19th shows me sitting on the now defunct beam to measure up for the hole to fit the velux window in the roof here.

Saturday, August 14, 2010

Center yourself

Trying to explain things again. The sketch is of the item in the photo (resting on its front in the photo). Scale wise, once again the tenons are 15cm wide, so measure up from there.
As a younger chap most of my woodworking efforts were add ons to existing structures. Working in this way one becomes accustomed to measure from surfaces so that the things being made will fit with what is already there. This is a nightmare when working on a house, as all the timber is of different dimension, you need to switch your brain around to work out from planes that run through the center of all the timbers.
Making a structure of an irregular nature requires this centered approach. I have written a bit about the center lines on all the work pieces in my structure. The most difficult joints are those at the head of the pillars where they mate into the shape of the rounded underside of the top beam. Because I don't yet have a fixed height for all the pillars I can let that remain unknown and simply push the pillar into the beam as far as I need to, cutting it to the correct contour and leaving the tenon as true as possible. When I know the floor level at the center of the pillar I will measure from the level line on the beam to cut the pillar to length. Well actually I will measure from the center of the tenon that passes right through the pillar as that is 60cm from the level line on the beam. That marker means I don't have to have the beam on the pillar when I measure. If I had to make a similar joint at the other end I would have to make a measurement from the center to figure out how much to chop back and hope not to mess up the joint and cut off too much. A more difficult proposition.
This is why I opted for the other type of joint here, the actual Japanese gateway structures this is based on only have a plank that passes right through both beams, I wanted something more solid, but with the same through tenon. Here the beam has a square shoulder on the tenon that is housed in a recess in the pillar. This is a more feasible solution where the width between the two pillars is decided. I measure out from the center where it is marked A on the right hand sketchbook page, then I subtract that amount from the width so that I know where to cut the shoulder on the through tenon. This distance, something like 6cm in this case (which means the squared pillar I need to keep in mind while working is 12cm square in section) tells me how deep to cut the recess in the pillar to house the end of the beam. The photo and drawing are of the south west corner of my structure, so there is a recess cut in the pillar to house the corresponding beam that will connect to the north west corner pillar.
The truck tie down ratchet mechanism with red belt (resting on the through tenon beam) was very useful to tug on the beam and pull the tenon home as I planed off scraps of material here and there. Applying tension with that and then nudging with some taps from a maul I made ages ago (Just checked, that was made on September 22 2007, a more regular posterson back then).

Tuesday, August 03, 2010


Topsy turvy photo of my progress so far. The back frame for the roof structure is now all jointed up and this trial fit seemed OK to me. I did the back first more by chance than anything, but it is sometimes a good idea as ones technique improves, so by the time the front is ready to be done the results are more satisfactory. In terms of perspective, this view point would mean one would be sitting up in a tree or hovering 50 foot up in the air looking down on the back of the structure I have in mind. There will be one more timber in the mix where the red tie down strap is pulling the beams together, more of a short plank than a post, possibly with some carved characters on. The mortises are there ready for it, as are those on the underside of the pillars to accommodate the ends of those two timbers furthest away on the rack (with flattened surfaces upermost) that will form beams joining the back to the front.