Part three of Introduction to Square Rule joinery series
Back to the Beginning
Let’s go back the original issue of what to do with timbers that vary in size and regularity, i.e. dealing with imperfect timbers; a question you might have considered was why not just use "perfect timbers" whose dimensions are known. Some modern timber framers do and these timbers are known as S4S, but the availability and practicality of acquiring these timbers is often cost prohibitive and/or impossible. The difference in material costs between rough sawn and S4S timber could easily be a factor of 4 or more. Imagine the machine required to accurately dimension an 1/2 ton 8 x 14 x 20′ timber, imagine the building that houses the machine and imagine the utility bill and imagine …. well you get the point. They do exist, but not many, and they certainly did not exist historically when timber framing was widely practiced as a trade. So how did the craftsman of the past solve the problem of creating accurate and sturdy frames if they could not produce perfectly dimensioned timbers? Because lets be honest it would be a lot simpler; at least in so far as cutting joinery is concerned.
And here the ingenious solution resides. It would be easier to cut joinery in perfect timbers and theoretically we could mill the large rough timbers into smaller perfect timbers with known dimensions. Now if what we are actually trying to accomplish is how to make the connections easier, then why not just mill the connections to the perfect dimensions that we know exist inside the timber and not worry about the rest. And there you have the simple elegance of square rule joinery. Simply adjust where the connections(joinery) are made as if we were using perfect timbers and in the end the problem is a lot simpler than milling an entire batch of timber. The concept essentially boils down to this:
Within every imperfect timber is an idealized perfect timber!
Examples of the Perfect timber within Imperfect timber.
By making adjustments to each side of the joint, reductions on tenoned members and housings for mortised members, we are creating perfect connections inside imperfect timbers. One of the benefits of this technique is that repetitive timbers (such as braces, joists, purlins, common rafters, etc) become interchangeable. This is one of the major differences between square rule and scribe rule timber framing. And now that the theory has been exhaustively explained (still with me i hope).Now on to implementation…. Choosing Reference Faces…. Next