Hello TIMBEAL,
I'm glad you responded to my post and I will try and address any points that warrant further discussion and/or validate further certain points.
In the Spike or screw the half laps, is another choice. Nails were used traditionally. Threaded tenon? have not come across this term.
I do agree that metal spikes of both bronze, copper and later iron, have been around for thousands of years, but only in extremely rare cases did iron spikes ever get used in traditional large joinery applications. Historically, in all global regions that have timber architecture, it is a very rare, to never, occurrence other than in cladding and smaller wood items, such as furniture. There is some application of iron rods, straps and bolts, but even that application is limited in traditional timber framing, usually reserved for public/industrial architecture and/or often added much later to repair a failed joint.
"Teasel" tenons, found here in North America, are a smaller form of the "threaded," tenons you may find in Europe and routinely find in some regions/forms of Asian timber architecture. Often pegged and/or "shim" wedged to resist uplift during wind events.
It is the amount of draw that can make for a tight fit, not the size of the hole. The holes in the tenon and mortice are the same size, just not aligned perfectly in each joint.
I was not insinuating that you, or anyone else needed to be a CNC machine, and I apologize if it I sounded that way. I agree with your assessment of trunnels used in draw joints but would point out that the size of the hole relates to the applied trunnel and the strength of the draw and the joint, both of which correlates to the accuracy of the trunnels shape and placement, this is proven historical, and empirically.
I validate this observation, by the tens of thousands of pegs I have either removed, replace or observed in frames throughout North America, and to a limited degree ,the Middle East and Asian. To keep the observation closer to home and this conversation, timbered house and barn frame trunnels are normally hand made, but most are very consistent and uniform in size and shape according to there specific application. The tapper is very seldom left inside the timber but out side, this is the case because the trunnels are most often cut flush and you must observe closely to determine which side they went in from. Pegs with random tappers and/or sticking out is an indication that the frame may well have been relocated and the trunnel a replacement. "Dead Head," trunnels have virtually not tapper in most cases I have observed or researched, often square at the end, such as in a Threshing floor.
The following quote is a good example of where I can pick out a slim peg and not wreck the relish. "If a peg is out of proportion enough to cause relish failure, you have a trunnel that needs to be replaced and/or shaped more accurately." ......If your draw is on the tight side and you insert a full sized peg you will bust the relish out. .
I stand by my portion of that quote and put simply it is not the peg that should be adjusted, it is the bore mortise in the tenon, and there is very clear historical precedence for my statement both in observed frames and in my training as a traditional barn wright. You seldom to never see large gouges of any kind in the tools of most modern timber wrights, but often, and commonly, find them in antique stores. The "why," is because this is one of the tools that leads to a technique that was commonly employed but is now lost and seldom implemented. Anyone that has done any extensive restoration or historical research can tell you that offset bore holes are sometimes elongated, this was done with a gouge. So I say again, you do not undersized the peg, you correct the bore mortise, that is the traditional method and the strongest of the two solutions, the trunnel is not suppose to be undersized. Also, note that gouges, both "V" and "out cannel," at one time here in North America, and still in Asian, were very common timber wrighting tools and really should be again.
When the craft of the timber wright began to weaken in the face of the industrial age, and the loss of a vast wealth of knowledge held by the people that went to the different great wars and never came home; many of the finer, but important, nuances of the craft, died with them. I have done everything I can to restore as many of those subtleties I was taught and have learned through research and restoration work back to this craft of timber wrighting. Trunnel methodologies is one that has many refinements that have been overlooked.
Yes, I have seen wedged half dovetailed tie beams with no pegs, the sad thing is no one came back and pegged it. In one particular case the joint had pulled apart by about 4 inches. It didn't even get iron staples. Don't get to see much dutch barn material in my part of the states.
I did not mention "dovetailed," joints but I will address your statement. I doubt very much that any one forgot to go back a peg them, seldom were they pegged, some in the mid span of a beam, maybe. They are a gravity joint and shim wedged is the preferred securing method if a "dovetail" joint is employed. The "pull out," failure you observed, (I'm assuming this was a vintage frame,) is a common failing for this joint, and one of it's weaknesses structurally; in frames with the shim wedging you seldom observe this taking place, which speaks to the variances in craftsmanship even in vintage frames.
quote from jay....
"Simply put, they should not vary in-size to the degree that one will not replace the other. If they do, they are not shaped sufficiently, and the technique of manufacture must be refined. Not sure what you are pointing out, but here is and attempt.
Again, the holes are not varying in size it is the amount of draw that is in question, and hence, by having pegs that are not cookie cut are handy, I don't have to set down on the horse and shave pegs during raising. Although I have been known to do just that, not my preference.
This again goes back to what I was stating earlier, your trunnels are to be uniform in size, shape and length according to application and if the layout and/or execution of a trunnel mortise is improperly offset, the method to correct this, is to adjust the the trunnel mortise not the placement of an undersized trunnel. Trunnel size may or may not contribute to the overall strength of a frame, there is some very strong academic debates about that still going on. IMO their size are of consideration but in this case, I am strictly addressing the draw trunnel techniques used historically and the methods that have stood the test of time.
Regards, jay
