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Re: Strength of tapered pegs [Re: Jay White Cloud] #30136 01/23/13 07:48 AM
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D Wagstaff Offline
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Hello,

There are a couple of gaps that could be filled in as the discussion goes on, though I would plead for making a clear distinction between peg or trunnel or what ever you happen to call it - here it is toognagel, just to throw that in - use and wedge use where a wedge comes into play, if I can say it without repeating myself because I don't see them as interchangeable in any situation.

So, the gaps, one being maybe already implied but not mentioned and that is, I guess it is understood the pegs are made, if properly conceived, from riven material. That was in my mind what might account for the variance Tim was going on about. Maybe not. The other, that for me is also unclear is the role of - now it's difficult because I always forget how it's called in English, here it's called the toogijzer- wait, drift pin, that's it. Using a drift pin in the assembly phase is in part meant to even out alignment where the holes in the mortice sides correlate with the hole in the tenon but that is only one reason behind its use. I think in order to understand draw boring the role of the drift pin has to be understood.

Greetings,

Don Wagstaff

Re: Strength of tapered pegs [Re: D Wagstaff] #30137 01/23/13 08:46 AM
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Jay White Cloud Offline
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Hello Don,

Save me from myself, you and I could probably, if we got together in person, really enjoy the conversations we would have over debating the finer points of things timber related, as we did recently. Tonight, I racked my brain to remember a point I was going to add to my previous entry about fitting draw joints. (I do agree with you, pegs, trunnels, or toognagel, they do have many names.) Now I can add it, but no better will I state it, than you have.

If you are assembling a timber joint, that is intended to be drawn together by an offset in the peg hole, and you can see that it is out of alignment, the use of an iron "Draw Pin" or "Drift Pin", (toogijzer-thank you Don,) was commonly used in traditional assemblies, this was not always the case, but more often than not, it was.

Since Don jogged my old memories, I should relate one of the first time I used a gouge on a timber frame and saw a real "toogijzer," (and I use that name as a nod thank you to Don,) and the fact that it was Dutch in origin, and belonged to the Amish barn wrights I apprenticed to. We are going back to about 1974 or 75, I was but a teen and only helping at that point. A bent was being assembled, there was numerous stages of fitting occurring, with the hands that were present for the raising. One of the joints had rejected it's "drift pin," and the timber was withdrawn. You could plainly see the misalignment, indicated by the compression line caused by the "drift pin." The layout of the hole was to close too the shoulder of the joint. One of the three men I answered to, came over and with a piece of chalk, darkened the compression line, and pointed to my gouge. (My mother was an artisan in several mediums and by that age I had already assisted her in roughing out carvings in both stone and wood, so I was comfortable with tools of this nature.) These men were kind but blunt when working, said little and expected work out of you. He pointed to the crescent shape of the chalk mark, said "cut no more," and walked away. I removed the designated amount, (about ~4 mm) the joint was reassembled. The "drift pin," was driven in, quickly removed and an oil soaked locust trunnel driven home. This would become one of countless lessons that I learned, that I have never read in a book, at least not in English. Again, thank you Don for the reminder, and a trip into my own memories.

Regards, jay


Last edited by Jay White Cloud; 01/23/13 08:56 AM.
Re: Strength of tapered pegs [Re: Jay White Cloud] #30139 01/23/13 01:25 PM
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TIMBEAL Offline
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Yes, all my peg stock is rived.

I for sure have not had the chance to work directly with or under a supervisor. As such, may be missing some of the nuances you mention, jay.

I feel as if you are painting me into a corner, jay. From your stance all my peg holes are horribly drawn and all need gouging, my worst nightmare. In my empirical experience I may see one or two holes out of a hundred which need a skinny peg. The vast majority of pegs I use are of a uniform shape, a heavy taper for the first 1/3 of the peg and mostly uniform, the remainder. It is my choice to use the ready peg which fits instead of gouging out the peg hole. In some important cases I have reshaped the hole, even plugging and redrilling.

The majority of my work is square rule and only fitted the day of raising. Of recent I have undertaken some plumb line scribe and fitted the whole frame with "wooden" draw pins. This was a humbling experience and more work.

In some cased the peg is of no consequence. So, just how important is the peg? If you know the limits.... you don't have to stick to the rules all the time, there are some freedoms.

No peg bracing.....
http://forums.tfguild.net/ubbthreads.php...amp;Words=unpeg

Re: Strength of tapered pegs [Re: TIMBEAL] #30140 01/23/13 04:41 PM
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Jay White Cloud Offline
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Hello Tim,

I do apologize if I came on to strong, that was not my purpose, nor did I intend to place you in any corner, again mea culpa. I just thought that Bob F. would benefit from what I had to share. I am more than confident that your frames are not in anyway at great jeopardy from your current pegging method. You seem to have great passion for the craft and think much about it.

I would like to deal with your comments about braces first. I have known of Rudy for a long time and loved that post you referenced. I was taught, and to this day, do not ever peg braces, it is folly to do so. I will stop at that, because it is one of my "pet peeves," that they are so often pegged, which is pointless considering the amount of wood they don't have on their tenons. I could ramble for a long time on this topic and the different methods of application, design and use of "compression braces."

Quote:
In some cased the peg is of no consequence. So, just how important is the peg? If you know the limits.... you don't have to stick to the rules all the time, there are some freedoms.
I do not really disagree with this statement, I would just amend it slightly and you can tell me what you think...

"In certain cases the peg in a joint is of little consequence, or it's labor is limited. Their importance may only be applicable during certain times, such as during some seismic or climate event. Many constructs of timber wrighting are only guidelines, some are rules, and if you have mastered a segment of the craft they may be bent."

Regards, jay

Re: Strength of tapered pegs [Re: Jay White Cloud] #30146 01/24/13 12:16 AM
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TIMBEAL Offline
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[quote=
"In certain cases the peg in a joint is of little consequence, or it's labor is limited. Their importance may only be applicable during certain times, such as during some seismic or climate event. Many constructs of timber wrighting are only guidelines, some are rules, and if you have mastered a segment of the craft they may be bent."

Regards, jay [/quote]

Yup, that is better.

I do like to peg braces, if only for assembling purposes. In most of this peg discussion I have been picturing pegging of braces. I should give a frame a go and use no pegs in the braces. My next frame will have no braces so I won't be able to apply it for that job. It is a plank wall with pegs in the edges of the planks giving it wracking resistance. Planks morticed into top plate and sill.

Re: Strength of tapered pegs [Re: TIMBEAL] #30147 01/24/13 12:40 AM
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Jay White Cloud Offline
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Hi Tim, et al.,

Boy, your getting into all the fun timber framing methods. I want to share a little something with you about plank wall construction, but first braces.

So everyone understands, I'm in pain at the moment from biting my lip. That way I won't get carried away with this topic, since its off the post's topic. Anyone that I have gotten to abandon pegging braces in their frames, has never gone back, and some will not do jobs if anyone insists they do. Enough said for now.

Why most timber wrights don't do one of these, or try to sell a room of a frame in this style, is beyond me. They are awesome. They have species of this frame type in every wood culture that I have found practiced. My Native American culture has several versions. If you combine this technique with some of the Asian horizontal pass through braces, you achieve the very best in framing: large thermal mass-better than most log homes, a flexible yet resilient frame, wall thicknesses can be doubled for a massive thermal barriers and the pass through braces give you a perfect framing for fenestration. Tim, you will have a fun time with this I'm sure.

Regards, jay

Last edited by Jay White Cloud; 01/24/13 12:55 AM.
Re: Strength of tapered pegs [Re: Jay White Cloud] #30148 01/24/13 01:54 AM
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Oh yes, it will be my third plank frame.

Re: Strength of tapered pegs [Re: TIMBEAL] #30149 01/24/13 03:47 AM
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I'd like to return to the original topic of peg strength. If the readers are guild members there should be an engineering peg report in the members section.

My personal bias in tapered pegs would be more to Tims liking in shape but not in the making. My tapered pegs are black locust, machine made with long taper and octagonal. The basic dimensions for a one inch bore are 61/64" flat to flat on the thick end, 3/4" on the thin end, tapering back 10" and 12" overall and point the end.

When driving the pegs, I align the bores with a erectors spud wrench, drive the peg making certain the joint seats continue driving until the peg tightens inthe bore and stop once tight. The basic problem is that once high resistance to driving happens compression damage occurs on the peg or in the bore, continued driving could shear short relish. When compression damage happens in wood the damaged fiber has lost forever it's compressive strength. Also prestressing the joint reduces effective capacity. So go easy.

Jay wrote earlier about driving pegs and mushrooming and splitting and cutting off the damaged end, In my view that is completely wrong, damaged on the end means the peg and bore are injured, drive it back out and replace. So use good technique, regard setting the draw bore peg as setting a spring, over driving defeats the purpose and weakens the system.

Re: Strength of tapered pegs [Re: Roger Nair] #30150 01/24/13 08:22 AM
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D Wagstaff Offline
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Hello,

Now, the shape of the peg in cross-section, that is whether it is round or faceted is interesting and up to now I have always taken it as a matter of preference, regional practices, or in the case of restoration, reproduction. Personally I do like a faceted peg because my sense is they drive more readily, but OK. Still, I think tapering it is ill suited to the purpose, my skew on that being clear by now. Though I do wonder at the loss of long grain in a machine made and tapered insert. It seems like really provoking the shear problem.

Reasonable compression of the tenon hole would not normally be a disadvantage, and that blow out at the relish is not only a matter of over stressing the hole in the tenon, but the fit of the tenon in the mortice in the height. A poor fit will allow the tenon to spread outwards and the only release will be out the back end so a wobbly fit comes at the expense of the draw allowance you can afford. You can put a clamp on a small piece of wood and drive a hell of a nail in at right angle and when the clamp is released the wood fibers will still be intact and stay that way. It also begs the question of the placement of the peg hole(s). I truly try to minimize the distance from the shoulder certainly not more than 1/4 of the length of the tenon. But yeah, taking it easy is key as well.

Greetings,

Don Wagstaff

Last edited by D Wagstaff; 01/24/13 08:27 AM.
Re: Strength of tapered pegs [Re: Roger Nair] #30151 01/24/13 08:35 AM
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Jay White Cloud Offline
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Even'n Roger,

Tim and I have established that my observation are just that, mine. I speak from my personal experience and the traditions I have been part of, what I have observed and of course, what I have been able to glean through research.

Quote:
My personal bias in tapered pegs would be more to Tims liking in shape but not in the making.
I don't have any great concern with this, but it is not the way it was done, and as a historical timber wright I will always speak against this as being what should be taught to younger wrights. Have I sawn out peg stock, yes, do I have the experience in assessing a piece of wood to do so, I believe I do, but I wouldn't want that method to be the first choice, nor do I think many young wrights have the experience to cut certain corners.

Quote:
When driving the pegs, I align the bores with a erectors spud wrench, drive the peg making certain the joint seats continue driving until the peg tightens in the bore and stop once tight.
Why wouldn't you use the tool that was meant for this, and in the manner it was meant to be used? Iron draw pins are driven to the point of seating the joint. Now, if there are two trunnel holes, you may drive the second peg with little effort. If only one hole, you remove the draw pin and replace it with a peg, and because the drawn pin has seated well the joint, you trunnel does not work as hard entering the joint.

Quote:
The basic problem is that once high resistance to driving happens compression damage occurs on the peg or in the bore, continued driving could shear short relish. When compression damage happens in wood the damaged fiber has lost forever it's compressive strength. Also pre-stressing the joint reduces effective capacity. So go easy.
This statement seams, at it core, to be sound in reasoning and one should always go as easy as they can, while still getting the joint well fit. If a trunnel is damaged, of course it must be replaced.

Quote:
Jay wrote earlier about driving pegs and mushrooming and splitting and cutting off the damaged end, In my view that is completely wrong, damaged on the end means the peg and bore are injured, drive it back out and replace. So use good technique, regard setting the draw bore peg as setting a spring, over driving defeats the purpose and weakens the system.
I will have to challenge you on your view that this is "completely wrong," because just because a tenon has begun to falter at the striking end, does not mean you have damaged the entire trunnel. Quite the contrary, if a trunnel is beginning to falter and you continue to strike it without the repair, you will damage it to a point that it will have to be replaced. Nor does it mean you have damaged the bore. The goal is not to smash a trunnel into place, but we all know that some do fail. If they present with shear failure, of course they should be removed. However, if the trunnels is well made and of sound wood, trimming the striking end a wee bit is of no great concern. For your second point, "over driving defeats the purpose," I may be reading your meaning wrong. The trunnel should be sound of nature and not damaged. If so, then it does need to be remove and replaced.

I know that I have said this before, and will most likely have to state it again, but what I share in my writing and what I teach isn't a personal theory or idea of what a method should look like. It is hard in written form for the following to not sound verbose, but I'm not guessing at how something should be done, speculating on what was done, or even sharing my own concepts. Most of the time, I simply state facts of the craft through direct observation and teaching from Master wrights, and/or almost 40 years of rather intense research, of this craft, not only here, but within many other traditions. I don't make assumptions, I make observations about methodology and with substantial cross reference. I hope that gives me some credibility when I make a statement about technique. I don't believe we really disagree that much, but I will always challenge a position that is counter to traditions that have hundreds, if not thousand, of years of empirical validation. That's not to say you shouldn't experiment and examine your approaches. I for one, 40 years later, still have epiphanies to what I was being taught all those years in the past.

Regards, jay

Last edited by Jay White Cloud; 01/24/13 08:43 AM.
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