First up, is to decide on the structure. Timber framing is relatively simple, requiring few tools, but some patience and a willingness to do things by hand. There are specific tools, hand and power, that help timber framers, but the hobbyist is unlikely to have a 16" circular saw or a chain mortiser! Hand saws and chisels will have to suffice.
I have large chisels, called slicks, in two sizes, 1 1/2" and 2" widths. I also have a shorter Stanley 1 1/2" chisel. The chisels are thick steel and stout. The handles have a top ferrule so you can beat on them with a hammer. A pull type handsaw is much easier to control and are very aggressive, though wet wood clogs then just as fast as a push type saw! DAMHIKT! I also had a new set of Irwin spade bits and an corded drill. Wet wood is hard on battery drills. And dimension lumber is wet wood. A dead blow hammer and a friend's band saw to borrow and I am golden. I added a router with a straight bit and a 1/4" round over. That should pretty much meet my tool needs.
I prepared a redneck sharpening station for the chisels and bought a new saw for $21. The sharpening station is nothing more than a strip of 240 grit PSA sandpaper pasted down on a flat surface.
The timber goes together with mechanical (not metal) joinery. That means joinery that can be locked in place. Mortise and tenon and all of its variations and dovetails. Off to SketchUp I go.
But before drawing, I made some decisions and wrote them down so I didn't go off topic and make this more complicated than necessary. Here is the list:
1. Keep it inexpensive. A tube/tarp structure is around $200 - my goal.
2. Use Harbor Freight tarp for roofing material. Only have to consider wind load.
3. Timber frame and joinery as it needs to be moved in the future. Weight of timbers ought to keep it on the ground. It will be permanently fastened to the ground with post anchors.
4 The overall size is determined by the tarp size. See below.
5. Must be aesthetically pleasing as well.
6. No cheating with the joinery. Every joint will have a purpose beyond fastening one board to another.
I had discarded the idea of buying a tubular/tarp cover from Costco or Harbor Freight. Waste of money in the longer term and ugly. One strong wind and one of two things, or both, will happen. The structure will leave the ground and fly off to the next county or will twist into a pretzel requiring a whole new structure. BTDT. Cost of those is around $200. So there is my budget.
Roofing material is expensive so I will use a silver tarp. They are cheap, work well, and if stretched taunt will last ~ 2 years. Again, BTDT. The trick is to fasten each edge so the wind cannot 'worry' it until it is loose. So the first measure is the easily obtainable silver tarp from Harbor Freight. I have a 12' x 16' on hand. Already saved $16 on sale.
Next is lay out the roof area so that it is 4" shorter and narrower than the tarp. This way the tarp can roll over the edge and be snugly fasten down. Along with the roof pitch this determined the length and width of the structure. I placed the posts in 18" for aesthetic purposes.
Size is subjective here. I am currently in a mobile home park so there is only so much room, and I have to take the structure with me or at least tear it down when I move. I am building a house so taking it with me is the plan. That means it have to be disassembled and then reassembled. That is the main reason for timber framing. Besides, it will make a lovely gazebo in its final destination.
Knowing the overall roof area, I now needed to decide on roof pitch. Here are two images that were helpful.
I like the 4/12 pitch. The roof will have a ridge board and rafters with a birdsmouth connection to the header. Now it is time to draw. You can certain do this with paper pencil and rulers, but the computer is ever so handy. I simply drew 4x4 timbers, 'milled' joinery on them, and set them in place. Just as I would actually do it. Then I was able to make a shopping list of materials.
Here is a list of the joinery. From post to side headers - 2" square tenon 2" long is a housed joint. A knee brace from the post to the header - same sized mortised and tenon but at a 45º angle. I added a curved bottom edge for aesthetic purposes. A connecting header from one side to the other. I decided on a 2x4 dovetailed into the top of the post. And additional 1x4 let into the top of the side header to cross header corner to resist racking.
A second knee brace from the post to the cross header is planned, but it's exact dimensions have yet to be determined. Two things to consider here. I would like to be able to back my truck with its lumber rack under this and do I want to use 4x4 or 2x4 material? But I have enough information to begin.
Here is what I have so far:
Off to the lumber yard and $168 later. I will need material for the cross knee braces when I decide what they will be. Other than that I have what I need.
Rafter details will come later.
To be continued.