The first is that boring machines are non-existant here. Those of us without chain mortisers are boring out our mortises with a power drill, often with no stand...
Is this a contemporary perspective and/or historical?
A bit of both. In modern times we either use chain mortisers (I'd guess 95+% of mortises are cut this way) or remove material with a drill and clean up with chisels. Some adventurous types may use an axe or some other chopping tool to hog out material, but mostly it's drill then chisel.
Historically I'm fairly certain that the boring machine never made it to France. The only models that exist here are American made and imported, there are no historical tool catalogues showing anything similar. I have the distinct impression that we went straight from the Tee auger to the power drill.
Secondly, I was taught "standard practice" here...
In regards to both the smaller size of timber (much more in the Asian size ranges) and to the practice of boring before the timber is mortised...Is this restricted to a contemporary practice or do you have citable documentation that suggest the "pre-boring" and smaller timbers was also an historical "standard practice" for you region?
I can't be certain, and it is possible that this is a contemporary practice. I have seen evidence that mortises had been bored out with an auger before clean-up (circular cut marks and centre guide holes visible at the bottom of the mortise) in old (17th century) timbers, but I can't be certain if the peg holes were drilled first or not. I will ask around, I'll hopefully be seeing François Calame of Charpentiers sans Frontières in few weeks and if anyone knows he will!
A mis-aligned peg hole can put more pressure on one side of the tenon than the other, or cause blow out of fibres on the exit side. But in large timbers this is rarely an issue (the peg just gets stuck)...
This is a very interesting observation. I have never read or heard of this being an issue within other cultures that often employ timbers of smaller dimensions (i.e. 100mm to 150mm square being common) and their related smaller tenons (i.e. 15mm to 25mm.) 30mm is excessively large (comparatively) for such small timbers. My simple grasp of timber engineering and years of experience within the craft would greatly lean me toward considerable concern for such a large tenon in such small timbers.
I was initially horrified. But I've since seen frames lifted after assembly on the ground (the circumstances in which tenons suffer the most) and while they creak, they've not blown out. And this in "commercial pine"... not even in oak.
In Asian, where timbers of smaller dimension are very common both historically and in the contemporary, tenons don't exceed (as I have seen, heard or read about them) more than 25mm to 30mm and that is in the 150mm size timbers. In the "folk styles" like Minka where members are larger, or in the Hanok of Korean we can see 30mm and greater sized tenon or doubling of tenon. In the 75mm to 100mm size timbers they are 15mm and 20mm...This is true in the Zafimaniry (et al) African traditions as well, which tend to use smaller hardwood timbers. I would also note that both cultures also employ "double tenoning" and/or toggling on a fairly common basis as well from what I have knowledge of...
Why do you believe that the French region of Western Europe developed such practices and beliefs regarding the 30mm tenon?
This is nothing but supposition on my part, but...
France has a very strange culture which is both left-leaning (socialist) and very (small c) conservative. I do think that this atmosphere led to the widespread teaching of a traditional technique (trait de charpente) and also, a strong conservation of tradition. But carpentry here (in the sense of the compagnons, and more generally the "corps de métier") has also adapted itself well to industrial developments. Delataille's books on trait include a series of pictures of truss styles for large buildings which often rely heavily on bolted joints. Rather than splintering into "traditional" carpentry (pegged) and industrial "bolted throughout" styles of construction, the whole world of carpentry assimilated the new techniques. Most "traditional" house roof frames now sport a mixture of bolted and pegged joints.
This anecdote shows an eagerness to adopt and adapt to industrial processes and (for me at least) provides a parallel to the adoption of square rule in the US. The use of a consistant tenon size in all timbers and a rule of "always 30mm" simplifies the design and construction process. It allows for faster throughput simply because fewer questions need asking. It's semi-industrial in that by accepting to be less dependant on the arcane knowledge and experience of the "ancestors", it enables the contemporary artisans to remain relevant and competitive.
But this is just my point of view.
What I really find interesting about this is that each person seems to have their own reason for drilling pegs holes after cutting the mortise. Which suggests that it's not a universal system because it's taught that way, or at least everyone has found their own justification....
I would have to challenge that perspective almost completely...
Not only from a contemporary North American perspective, but additionally an historical one as well. Both here and internationally...It is very much "taught," that you bore a pin, or peg hole...after the mortise is cut...not before...in my experience, and knowledge of the craft.
I phrased that badly. I meant to suggest that the reasoning is not taught... clearly the practice is. What I find interesting is that I was taught this practice with an explanation of why it "should" be used. This does not appear to be the case in the US. I can't speak to Asian timber framing as I have no knowledge at all in that area.
Your shared "pre-boring" is not something I have ever seen, read or experienced before this conversation, and does seem to be a contemporary manifestation within the craft of your region.
Not in any of the timber framing traditions that I am aware of or versed in...Africa, Middle Eastern, Most of Europe, or Asia is "pre-boring" commonly practiced. If at all? That is not to imply that the practice doesn't exist in some other timber framing cultures? If others know of any...I would love to read or hear about it.
All mortises here are 30mm...Neither in modern construction, nor in any of the older buildings that I've worked on...
Jon, when you describe "older" could you give a range? Are we speaking of 19th, 18th, or 17th centuries?
The oldest I've worked on that was reliably dateable was 18th century, dating in fact from the period of the revolution (Which might have explained the change in framing style of the roof which felt like the entire team had changed halfway through construction!). I've also worked on vernacular buildings which may have been even older but I've no way of being certain.
