Preparing the posts

Since we got the timber a few weeks ago I have been trying to work out a) how to handle the timber and b) how to cut it up. The posts are unseasoned 200mm x 200mm (8" x 8") x 2.7m dense hardwood. As mentioned in an earlier post they weight around 150kg. The main beams are 300mm x 70mm x 4.8m.

The first challenge was to move them around and handle them. The came in packs, there were 2 packs of the posts and then the several packs of mixed beams, ring beam, purlin and fascia. We have started to sort the mixed packs out into their own stacks and in the process putting spacers between the timber so that air can get around the timber and help minimise uneven drying and warping. To move the bigger timber members we purchased a furniture trolley with big heavy duty wheels. Myself and Sharon are able to load the timber onto the trolley and between the two of us are able to move the timber to where we want.

The next step has been cutting the timber up to use. We are going to put up the center ring first and then the outer. So we started on cutting up the center posts. This requires cutting the bottom flat and the top on a ~7° angle and then a slot in the top and bottom that is 200mm deep and ~10mm wide. We tried a few different methods for cutting up the big timber

1) Chainsaw - this worked ok, it was the quickest cutting but the draw backs are you have to be careful that you are straight as it does cut quick. The chain tends to chip the timber at the cut and the last thing is that it covers the timber in chain oil.  It also requires maintenance, checking fuel/oil, sharpening and starting.  It uses fuel, is noisy and creates fumes.

2) Handsaw - this method is quite slow, but it is quite accurate as you can monitor the cutting as you go along (usually while giving your arm a rest). the cut is nice an clean with minimal chipping at the edges. I use a Spear and Jackson crosscut saw with 10ppi.

3) Circular saw - The biggest circular saw that you can get from a hardware store appear to have a cutting depth of 85mm, so drawback of this method is that you end up with a bit in the middle of the 200mm post that the saw can't reach. Also the post faces are not exactly perpendicular with each other and vary in size from 190mm to 205mm (so far these are the 2 extremes I have encountered).

The method I have ended up using is a mix of 2 and 3. so I circular saw as much as I can and then finish off with the handsaw.

Marking up the posts has been the most important thing, and as mentioned the posts are not square. The most important part of cutting up the posts is the height and that the slots at each end line up with each other, if they are at an angle to each other then the top bracket will not point to the center of the house which is a big problem. So to line up the slots properly I ended up choosing the face of the post which will face in toward the center of the house and then measure a constant 100mm (to the center of the slot) for all post no matter what the actual diameter was for each post. This will give me a constant distance from the center to the face.

To cut the slots we very carefully marked them up making sure that the top and bottom slots lined up. We did this by marking up the top and bottom together, the distance from the face was the same for the top and bottom and we used a tape measure from top to bottom when marking them. When both sides of the slot were marked we then joined up the side markings along the ends. To cut we used a circular saw. A cut was made on each edge of the ~10mm slot on both sides of the post, the big thing here was to make sure that the saw depth cut was inline with the end marking since each face of the post is not guaranteed to be 90° to the others. I did this by lining up the saw blade angle by eye with the slot end markings and then watching as the saw cut that it was staying true, if not I would account for the difference by slightly tilting the saw while cutting. The top of the slot was pre-drilled using a 10mm auger bit and the material left in the slot was hand sawn out using the crosscut saw (I will have to look around for a rip saw I think, since the crosscut while it worked took a while to get through).

The other issue we had was to drill a 'straight' hole through a 200mm chunk of wood. My drilling is not that accurate that I was confident of doing this for every hole (each post has 4 holes). The stirrups and the top brackets are all pre-drilled with 18mm holes. The bolts are M16 so there is a 2mm allowance for error. Since the timber is green this will allow for some shrinkage too. But because the steel is drilled we have to get the holes in the timber pretty accurate, a crooked hole would look bad but more importantly it will probably mean that the bolt won't fit through. To solve this problem we ended up marking the hole on both sides of the timber off the front face, this involved using a square on the face and measuring the opposite hole from the square, which should align the hole exactly perpendicular to the slot. We then drilled the hole about 3/4 from both sides. any slight variation on each of the holes was then 'adjusted' by re-drilling so that the two hole match up. We bought several sized augers and have found that they are brilliant for drilling nice straight holes through the timber, they literally pull the drill through the material.

We have now cutup the first 10 center posts and they are ready to put up, but before they can go up we need to cut up the ring beam timbers (240mm x 70mm) and get the top bracket made up. The top bracket joins the top of the center posts to the inner and outer main beams (these beams radiate out from the center) and the ring beams (they join all the center posts together).