Wednesday, May 8, 2013

Chapter 8 - Deck Framing

Chapter 8 - Deck Framing
Now that I had an on site place to live, complete with running water, electricity and an outdoor flush toilet, I was finally ready to start my timber framing project. I left my four month long foundation project in Colorado on August 13th, 1995 and returned to Pennsylvania. I found that Keith had all of the deck timbers except the joists cut and ready to be delivered to Linda’s yard. My old employer wanted some assistance with the project of converting my software masterpiece to a new operating system too. And, as I expected, Ed would be happy to have a free employee any time I felt like showing up. So, I spent the winter in Pennsylvania crafting deck timbers in Linda’s garage, solving software conversion problems and learning as much as I could from Ed.
Ed seemed very skeptical about my plan to use Linda’s garage as a timber-framing workshop. He even offered space in his shop so that I could use his tools! This idea, having seen the pile of timbers that I had to work with, seemed like a whole lot more work that necessary. Since I was committed to building the frame in Colorado, getting the tools that I needed to work in Linda’s garage seemed like the best idea. I purchased the basic woodworking tools: a 7 1/2-inch circular saw, a 3 1/2-inch planer, a 3 1/2-inch belt sander, a heavy-duty drill and 1 3/8-inch Forstner bit. I already had my 1 1/2-inch, 2-inch, corner chisels, mallet and whet stone and some basic measuring tools such as a tape measure, combination square, carpenters square, inside and outside calipers but needed a 4-foot straight edge. I also had two pipe clamps but found that two more would be very helpful. The 1-inch ratchet straps that I had were okay for small jobs but two 20-foot 2-inch ratchet straps were far better to hold entire bent assemblies together. Safety equipment such as safety glasses and hearing protectors seemed like a good idea. My antique crosscut saw had belonged to my grandfather, so I got a new one and a new ripsaw seemed like it would come in handy too. Being used to large circular saws from working in Ed’s shop, I got a 10-inch circular saw though I only used this monster when absolutely necessary. With all these heavy-duty electrical tools, a brand new 14/3 gauge, 50-foot extension cord was also a good idea. Although it didn’t seem necessary at the time, I also purchased an engine hoist, eight 6-foot and two 3-foot nylon straps and two heavy-duty come alongs. The come alongs would be necessary for the future raising. Although the engine hoist was only useful on the concrete floor of the garage it did save a lot of tedious timber lifting.
The goal and plan for the winter was to make a little money, do a little timber framing apprenticing and make the parts for the daylight basement decking. When the deck parts were all cut and ready for assembly, they would be loaded on a flatbed truck and hauled to the building site in Colorado. This part of the plan went very well. By May of 1996, the flatbed truck was loaded with everything I thought that I would need to assemble a timber-framed deck on the daylight basement foundation.
The major part of the timber crafting was the 4 two-piece sill beams and the 2 two-piece center girts. The center spline joint joins the two ends of sill beams and center girts to create a long timber to span the 40 feet of the daylight basement.
Before I started, I followed Ed’s advice and built a set of hefty sawhorses. This exercise actually serves two purposes. First, I could finally have a set of sawhorses that were short enough for me to comfortably use. For some reason, all of the timber framers that worked at Ed’s shop were giant guys who used sawhorses 36 inches tall. I was constantly standing on blocks of wood. My sawhorses are 28 inches tall, which puts an 8-inch thick timber at a comfortable working height for a 5-foot 9-inch fellow like me. Second, building timber-framed sawhorses is a good way to tune up your skills and tools without jeopardizing a rare and valuable timber.
Another one of Ed’s rules was “never put a timber on the ground”. Being a good little apprentice, I never violated this rule, but Ed never explained its purpose. I just assumed that this rule prevented damaging the timber somehow. As soon as I started trying to maneuver my 660-pound, 22-foot long 8x10s, the reason for this rule became obvious. Once a timber weighing hundreds of pounds was on the floor, getting it off of the floor becomes a nightmare. You need at least enough space under the timber to get a strap around it to pick it up.
In fact, the farther timbers are above the floor, the easier they are to move around. Because of my training in the science of physics, I knew the ultimate reason for this phenomena; it’s called gravity. The past several years dealing with extremely heavy objects that often need to be many feet over the ground, has given me a whole new respect for this force of nature. Not only is gravity reliably dependable, it acts instantly, without your permission. Having your fingers under a timber when gravity takes over is usually painful. It’s always a good idea to have something stronger than oak and thicker than your fingers readily available at all times.
The basic tools that you get very good at using to combat gravity are the lever and fulcrum and locating the center of gravity of an object. The lever and fulcrum allow you to lift a very heavy object a short distance and placing a support under the center of gravity of that object magically makes it weightless. With these two intuitive principals and a lot of practice, no timber is too heavy to move, it just will not be moved very far, very quickly. If you are not familiar with the virtue of patience, the practice of timber framing will teach it to you.
It’s easy to take the power of cranes and winches for granted. At the push of a button, a 500-pound timber simply rises into the air. Working alone without these magical devices forces the discovery of the more fundamental principals behind these clever machines. Let’s say that you were silly enough to violate Ed’s rule, and you have a 500-pound timber lying on the floor, and that you need to get this timber up on your sawhorses. Start with a wedge shaped object and, beat it under the end of the timber. This raises the end of the timber to the thickness of the wedge. Now get a block about the size of the space that you have created (a fulcrum) and a long, strong stick (a lever). Put the end of the stick under the timber and slide the block on the floor, under the stick as far as it will go. Pushing down on the long free end of the stick will raise the timber end a bit higher than the block. Next, slide something under the timber about the size of the gap you just made. Repeating this process with progressively thicker fulcrums slowly raises the timber off of the floor. At some point you can get a support block under the center of the timber. If this block is at the “center of gravity” of the timber, the timber will balance on this block with both ends off the floor. If you place a similar sized block at either end of the timber and slide the timber over this end block, your 500-pound timber is now securely supported off of the floor. Repeating this process with progressively thicker fulcrums and support blocks will eventually raise the timber to the height of your sawhorses. One quickly learns to keep a supply of various sizes of wedges, support blocks, fulcrums and levers as part of your tool collection.
The next trick is to move the raised timber from the support blocks to the sawhorses. Experience teaches you to place your support blocks as close to the center of the timber as possible while still firmly supporting the weight. If the timber is not too heavy and your support blocks are near the center of gravity, the end of the timber is much lighter than the entire timber and can simply be lifted and pivoted onto one sawhorse. If your support blocks were carefully stacked and fairly stable, you can slide the timber on the surface of first sawhorse close to the center of gravity of the timber and easily pivot the other end onto the second sawhorse. What this all means is that the separation of the two sawhorses is critical. The ideal separation is just a bit more than half the length of the timber. That way the timber can be slid over one of the sawhorses while the other end is still supported. With practice and caution, it is even possible to spin a 500-pound timber all the way around while balanced on top of one sawhorse.
Once the timber is on the sawhorses, crafting joinery requires access to all four sides of the timber. This is where the value of good solid timber framed sawhorses becomes obvious. One can, with practice, roll a timber from one side to the next. Always roll that timber away from you. It may seem easier to roll it toward you, but if it slides unexpectedly, it can wind up in your lap!
Knowing the exact dimensions of my foundation, I started by making the two scarf jointed 40-foot long center girts. Each end of the two-piece center girts has an 8-inch long, 2-inch by 8-inch horizontal tenon. This tenon will fit a housed mortise in the side sill and be pegged. This peg will also serve as a peg for the bottom of the frame posts. The 2-foot long centered scarf joint has a centered horizontal housed mortise for the 8-inch long, 2-inch by 8-inch tenon of the center beam that extends to the front and back sill. This tenon is also pegged and this peg also serves as a peg for the bottom of a center frame post. I also put a vertical 2-inch by 5-inch mortise and tenon on the topside of one end of the scarf joint and on the bottom side of the other end of the scarf joint. These two tenons are pegged from the side of the girt, adding rigidity to the scarf joint. Centered between the center scarf joint and the end of the girt on the outside edge of each girt are two large housed dovetails for cross beams that extend to the front and back sills.
The two sills that run parallel to the girts and fit at the front and back of the deck frame are mirror images of the center girts, except that the two ends have a dovetailed tenon that fits a dove tailed mortise at the ends of the side sills at the corners, a tongue and fork joint. The two side sills are similar to the center girts, except that the through mortise in the center of the scarf joint is eliminated. This through mortise is instead placed 4 feet from the center of the scarf joint for the tenon at the end of the center girt.

No comments:

Post a Comment