It is an evolving process, and that is what makes the craft, a craft...
There are different approaches to mapping, reference, etc. And people all approach it differently
The big driving difference I see between Swiss numerical scribe and American Square rule (really when I analyze the two, they are so strikingly similar in concept and practice, with just 1 or two slight, yet profound differences) is one that is centered on the way the two cultures look at a frame.
In America, a frame is a thing of pure utility. They made the frames to support the buildings, that was it. So you approach your joinery with a very practical viewpoint.
If it was a barn you built, it's ok if it is so rough and utilitarian. If it's a house, well you are going to wrap the whole thing and no one will see the frame (talking historically) so what does it matter how the frame looks.
Suddenly in modern times the frame has been thrust back into the spotlight, and these things matter again. But it seems to me, so much American mentality has been shaped by looking at the only frames you could actually see -barns.
But we have a very different situation in Switzerland. Here the frame is and always has been out in the open, visible, and a focal point of the architecture. It really really matters to a Swiss carpenter what the joints look like. The frame itself is very refined, neat, and well ordered. So of course so should the joints be.
Americans have developed this sort of romantic idea about a timber frame, having this rough frame of huge, hewn timbers, or otherwise some sort of rustic idealism. And that is fine, I am OK with that. It's just different. In Switzerland you would never do that, at least not within the context of traditional Swiss Holzbau. I totally understant the rugged idea. A lot of that comes from the American pioneering spirit.
So the idea of cutting reductions and housings makes perfect sense in American timber framing.
In Switzerland, its perfectly absurd.
Because the two cultures look at the frame with a totally different mindset.
And this is really important to this discussion. The Swiss are going to come up with an approach to layout that makes everything look ordered, regular, and well adjusted. They are not going to be satisfied with cutting a reduction at the joint to make it fit. Rather than do that, they would reduce the entire face of the timber. Now as to joints bearing on tenons, in Swiss carpentry they always do. BUT it's important to note that the design of the frame is such that timbers that need to transfer a lot of weight do not do so with a mortise and tenon joint, so the idea that this joint should be housed to support the weight more efficiently doesn't come into play at all. As we can see, there are a LOT of variables at play here, and it all comes down to the fact that here we have two totally different building cultures with extremely different ways of doing just about everything.
The old style of Swiss framing, Ständerbau, relies on heavy timber frames with a solid wood plank infill. The whole things is cut and fit together perfectly, the planks carefully fitted, and everything is neat and orderly. There is absolutely no room in this system for unorderly joints or irregular timbers. In the Canton of Bern, the planks were often pretty thick (like, say 4 or 5 inches) and fitted into the frame with tenons. You saved yourself a whole lot of work if you reduce the posts to very regualr dimensions, and can just cut the planks in a given cavity to a consistent size.
You have a parallel to this in log building just to the south, where the wall logs fit into heavy uprights framing the doors and windows. Again, with a tenon fitted into a groove in the upright. Here the process works in reverse, the wall is laid out on the ground, the location of the opening snapped, the openings measured for post height (calculated for settling) and then the posts are made to perfect dimensions, fitting into an opening that is cut perfectly.
So again to be clear, in the frames the posts were made perfect, then the planks measured to fit between them. In log buildings the logs were cut to perfect lengths, and the posts measured to fit to them. But all was greatly simplified by making sure the timber faces were as true as possible
I can attest this practice in log building as far back as the 11th century. In Ständerbau as far back as the 14th (probably much further, it's just that happens to be the oldest framed buildings still standing)
Going back to the frame as a thing of utility,
Americans have become used to that rough, rugged, utilitarian frame look. the American idea of timber frames is again shaped by looking at dusty old barns and thinking that's what it should look like. So it makes perfect sense that the idea of housed and reduced joints is acceptable. And that's not an insult at all, I am simply stressing the point that these two building cultures place the emphasis in entirely different places.
Again looking at the Swiss frame, we are a people that are mind-numbingly obsessed with detail. Little things matter a LOT, and everything has to be just right. Square rule carpentry just doesn't fit in that worldview. Again I don't say that as a criticism, but here to maybe explain when I say, why can't I just forget about the housing and map the joint, this is why. I'm working from a different mindset. I bi stolz e Schwyzer z sy
To me it just makes more sense to adjust the length of the adjoining timber. I know in my mind, if I make the joint face at the mortise regular and adjust the adjoining beam to match, it will work. But I am good at envisioning things, at taking complex things apart in my mind, disassembling them and seeing how they all fit together. It's easy for me, most of the time, to visualize how a change in one place affects the whole.
I would be interested in hearing more about the mapping technique you came up with. Even if it wasn't an ideal approach.
