Thanks to all for you contributions. I still hope I will find someone with experience in this method. Thanks Will B for comment, I know scribing techniques with scribe (compass-like tool) and I've done several logs. I understand how to use the cribe though I am not scribing specialist.
The logs on the pictures above are not scribed with traditional scribing technique I think. The logs were not set one over another. They were not scribed with scribe. They were prepared separately. It is interesting how precisly is possible to transfer tenon and mortise size to irregular logs.

Ferd, although I did not attend the conference where the presentation was offered nor have I been instructed by Robert Chambers, I have used some of the ideas underpining this method. The regulating concepts are a level and lined log, tools that detect plumb, level and square and finally control of slicing planes at closely controlled angles. The innovation here is in the use of a template with the elliptical cutout that models the miter plane. So by straddling the log held precisely at the miter angle, the log can be marked by projecting the plane to the log thus marking the cut line. The real challenge here is to make the initial cuts into the receiving piece while retaining the material for the saddle. Then the saddle is developed and cutting is continued.
so in a way this is not to my way of thinking a scribe process but rather more of a mapping out process.

Roger, I understand it the same way. The first step is leveling the beam log, the second step: draw vertical and horizontal cross on both ends of log and connect them along the log with chalk line.
OK, the next questions. I understand how this big board with elliptical cutout can help to draw line around log. If I hold pencil on the template surface the pencil line will be flat even on curved log. But is this template general-purpose (for all logs) or is it done differently for each log diameter? Why are there two cutouts? The bigger one (elliptical) is probably for sloping lines and cuts. But why is there another circular cutout? Is it for right angled or perpendicular cuts? Or for different logs? What is Robert doing on the first picture? What is measuring on the pictures #2, #5 and #6? And why? Is there any other way than using this big board with cutouts? As I said-I have a lot of questions....
Another question: the beam and the rafter here in pictures have almost same diameter. How to proceed if diameters are different and rafter is smaller? Then the crossing of both logs will be above the beam middle line..

Here are my thoughts having seen bits of the presentation, from knowing what the joint looks like, and from looking at the photos:

centerlines are established on the logs

geometry developed based on the centerlines for a rafter to tie connection
(with logs of similar diameter, one could assume a near center line to center line match in how the logs plane out to one another)

the geometry of the joint in this case is developing 2 planes as primary to layout, and an interior rectilinear block of timber

the elliptical cut outs are simply a convenient way to trace the planes onto the surface of the logs - i would guess one could have several of these for various angles and log sizes - but if the cutout is close in size, flat to itself, with the angle held correctly, and the pencil used judiciously, it would seem you could make this work with a few templates - longer ellipses for shallow angles, shorter for steeper - and i'd imagine a scenario where having a bubble gauge or inclinometer mounted to the patterns would be useful

once the planes are developed, and the angles off of centerline known - the geometry can be added to both timbers

the rafter is easier to cut - in that the 2 planes can be cut completely through, and any interior joinery removed later

the tie is more difficult - as the width of the interior rectilinear shape needs to be projected onto the curved surface of the log before cutting so that one maintains the internal shape


i see timberwrestler in a few of those photos - i'll see if he can comment. and i'll try and get robert chambers to check in here. his website is here - there might be some useful information there:
http://www.logbuilding.org/TOC.html

and he makes these great scribers (i have no need for them - but have held them at a TFG conference):
http://www.chamberslogscribers.com

In this case, I think the template is specific to the logs diameter and the varied slopes of the planes requires two different elliptical cuts. I think that there is a close tolerance in the cuts to limit error in transfer. Also this looks like a center line layout, so the origin of the layout is on the horizontal center line. Therefore the template must extend past the critical dimension mark, so the template can be assured to register on the mark.

Since I did not witness the demo, I think that any specific comments on each photo could be wildly wrong. A number of things are not clear to me in the photos. I can guess but I'll pass for now.

Roger,

If the plane is held at the correct angle, and the pencil held flat to the plane, then it would matter little how close the ellipse follows the timber - so long as there was enough meat for the pencil to ride accurately. This assumes that there is a way to register the template to the proper location on the log without relying on the templates fit to the exact curve, as you'd need an awful lot of templates - unless you were working with very closely sized poles.

The trick I want to know is how the planes are held at their exact angle once their position is determined on the log.

But yes, it would be good to hear from someone that was at the demo.

My observation relates to the photos. It does seem to me that the template must register to the critical dimension marked on the horizontal reference so a reasonable closeness is needed.

With a level log, I would gauge the slope with a Bosch electronic bevel, it's in my kit. Not a clue to how Chambers goes about this.

Hello Team,

Sorry that I've missed the conversation. Busy.

At conference I had a full classroom session plus a demonstration, and that was not enough time for anything but a brief introduction. The method is new, the joinery is new, and the layout methods are new. At least, I've never seen this before in my 30 years of working with big wood.

First, a few comments on philosophy and my life. For those who think that all wood should be either square or round -- that's a rather small idea. The TFG members who I know, and who I work with, don't see it that way. I choose to work with logs because I love the look of naturally-shaped, smooth, tapered, hand-drawknifed trees. To 'neck' a beautiful, naked, natural log down to a square timber at the joinery is against my religion. I won't be discussing my religion in any further posts. No need to comment on the superiority of square since 2x4’s are square. And it’s quite easy to make strong buildings out of them. So, it is obvious to me that the 'square' idea is not the best idea to be found in timber framing. I think your best idea is more likely to be the 'big wood' idea, and the traditional joinery idea.

Sometimes I use a scriber to transfer the natural contours of one log onto another natural log. Log walls are built that way. But for structural assemblies, it’s difficult to make scribed joints strong. Not impossible, but difficult. But the second problem is that the initial super-tight fits of scribed joints and notches suffer unless we can use gravity and shrinkage to help us keep them tight. The corner notches of log walls get the benefits of gravity, compression, and shrinkage, and these keep our corner joints tight over time. But we don't get all those benefits in the joints of, say, a roof truss made of natural logs. So, using only scribed joinery for space-frames like trusses, or bents, is not a good idea.

My new joinery is not scribed, but it does appear to be a scribed joint because the surface contours of the two logs intersect cleanly, as scribed joints do. My new joint shrinks together, and stays tight over time. It also has big, flat, bearing and shear surfaces totally hidden inside . . . and the engineers tell me they like that. Ed Levin was my co-presenter at the Vermont conference, and Mack Magee at the log builder's conference— maybe Mack can answer engineering questions in this thread?

Each log gets 4 chalklines, and at both ends they get 'cross-hairs' connecting the lines. In a truss, the 2 chalklines that are in the plane of the truss are snapped so they divide log diameter in half at the joints. These sorts of chalklines will be familiar to some of you. But, the 2 chalklines that are in the horizontal plane on each log, are snapped so they go through the thickest part of the log at the joints. (If I used machined logs, then these 2 horizontal lines would be the same as the ‘thickest part,’ but since the logs are naturally-shaped we need to reference off the ‘thickest part.’) You can think of ‘thickest part’ as being the greatest diameter (but actually it’s the longest chord length). This horizontal chalkline is a new kind of chalkline.

Where log meets log, both logs should have close to the same diameter. The closer the two diameters match, the better the joint looks when it’s finished. Here’s why: When two cylinders of equal diameter intersect at their midpoint axes, the joint surfaces are made of two flat planes. (The edges where the two cylinders meet are not straight, they are hyperbolas.) Equal diameters (chord lengths) is the key to good looks. And of course, the interior, flat bearing surfaces are easy to cut (because they are not coped).

If two cylinders have unequal diameters where they are joined, then you get a complex curve in three dimensions -- and if you want the joint to look good, then it really has to be scribed to make the surfaces of the two cylinders meet happily (and that's how boilermakers weld these type of joints). Again, this is why I am not using logs of unequal diameters (at each joint). Of course, the logs are tapered, so their diameters vary at each truss joint. It is easy for log builders to find logs with equal diameters at each of the joints because we have a lot of logs in inventory. This lack of choice will be a hurdle to timber framers. If you try my method to join an 11" log to a 12 -1/2" log you will be very unhappy with the result.

The ‘vertical’ chalklines, in the finished and installed truss, are in a single plane, and this plane is plumb. The ‘horizontal’ chalklines, when viewed in elevation in the finished and installed truss, are perfect right triangles, and the pitched chalklines of the top chords are at the roof pitch. The horizontal chalklines meet at points on the surface of the logs (which is the 'hinge' of each joint, where the two internal flat surfaces meet).

We will be building one of my trusses at the ILBA conference on Vancouver Island, in a hands-on course March 26-27, 2014. www.LogAssociation.org I’ll be publishing a booklet on the method, and maybe an article in Timber Framing—Ken and I have talked about it. But, it's still new, and I want to use it more before I get it into print.

I do not regularly scan these forums, so I apologize to you in advance for my future slow responses.

Yup, I was at Robert's talk and demonstration. Very cool stuff.

Ferd, it's really a very specific joint for pretty specific situations. It's technically a mitered joint, but only for logs with the same diameter (as Robert pointed out). You can miter logs with different diameters, but you end up having to fair them out at the joint, because they will never meet perfectly. What Robert realized by looking at some obscure geometry is that they do perfectly meet when the diameters are the same. The result is a really clean joint, that also can include some internal joinery.

He presented a few methods of executing the joint. The standard way would be with lofting, but there are some disadvantages to that. The method he is showing is basically using a template. I'd have to review my notes to try to explain it, and it's not something that is very explainable in words alone. I don't think that he's measuring in those photos, but rather bringing a point up from the template.

I can try to answer more specific questions, but most of this sort of thing is hard to explain. I would definitely check out Will's articles that he mentioned. And the ILBA has a book on cutting with jigs that goes over a bunch of different approaches.

Each joint has two joinery planes. If we have 3 points on the surface of a natural log then those 3 points determine one joinery plane. Another layout method requires only 2 points plus the slope of the joinery plane (2 points and an angle determines a plane, as does 3 points). Which method is preferred depends on how fast you want to work, whether your logs are roundish in section, or are oval/lumpy/weird, and how many jigs you want to own.

Two of the points that we need for both layout methods are easy to establish: these 2 'easy' points will always be located on the horizontal chalklines. And, if you could connect these two points with a line through the log, then that line will be normal (90 degrees) to the plane described by the vertical chalklines. (You cannot actually connect these two 'easy' points until after the joint has been cut, of course, there's wood in the way!) I call these 2 easy points the 'hinge' points -- because the two joinery planes of each joint appear to hinge here. There are always 2, and only 2, hinge-points per joint.

For the 2-point-and-angle method, once we have the 2 hinge points, we need the angle. Each joinery plane bisects its involved angle. I love how simple this is; and the engineers like that the bearing surfaces are always exactly the Hankinson angle they want for grain slope. An example: two logs to be joined to each other at 45° (eg the top chord of a 12:12 truss joined to the bottom chord). The joinery planes for this joint will 22.5° (half of 45°) and 67.5° (half of 135°). These angles are measured from the horizontal chalklines of each log. A piece of MDF can be positioned like a horse collar over the log, and it is lined up with the 2 hinge points, and then is set at the desired angle. (The MDF in the photos is not a template: it has no markings on it, and the ellipse was roughly cut only so it would fit over the log. It is a reference plane, not a template.) Trace from the MDF onto the log’s surface. That’s your cut-line for this first joinery plane. Re-position the MDF through the hinge points and at the other angle you need for this joint. Then repeat on the other log that will join this one (one is male, and one female, of course). All measurements (span, height, length of pieces, etc) are made along the horizontal chalklines. That is, the length from one joint to the joint at the other end of a log is a measurement from hinge-point to hinge-point, and the required length is found by trig (or proportions, pythag, or etc). All the joinery can be laid out on all the logs before anything is cut, the logs are never positioned over each other, are never leveled lengthwise, there is no lofting, and no lines are snapped on the floor.

I should mention that snapping accurate chalklines on natural logs is not as quick and easy as it might appear. There are unique skills to putting chalklines onto logs. The line must be aimed, not just pulled back and let ‘er rip, but that’s another topic. Just a heads-up that you need skill in the basics to get good results here.

A much faster way to lay out the 2-points-and-angle can be viewed in my short video here:
http://youtu.be/hO6w3njpzqY
In the vid, ‘HP’ is hinge point—you can see that the jig really does hinge on these two points, and then is locked at the required angle. The 2-point-and-angle layout produces joinery planes that are always 90° to each other, so you set the jig once and mark both joinery planes. (It’s great the way the geometry works out. I wasn’t expecting this when I first started working on it. But when layout, engineering, & cutting all click like this, I knew I’d found something sweet.) If you’re keeping score-- from the example above, you’ll see that 22.5° plus 67.5° = 90°. For accuracy, I use large MDF triangles cut on a table saw to the angles I need, not that tiny digital protractor. And my jig, made of “8020” parts, has been slightly improved since I made the video last summer. The truss in the still photos was built by students in my 2013 Univ of Alaska course. They had no timber frame experience, and had been working with logs less than 3-weeks. This was the first-ever truss built using my method and joint, and I think they did a pretty good job with it.

Now, for the 3-point-layout, which is the method I demo’d for the TFG, we use the 2 hinge-points (identical to the HP’s used in the 2-point-and angle method) but we also need to determine where on the vertical chalkline the surfaces of the two logs will intersect after they have been joined—we need ‘surface points.’ If the logs are not very circular in section, or have substantial sweep or bumps, then the 3-point method can produce a more attractive joint than the 2-point-and-angle method. (Not a better fitting joint, a joint that has log surfaces that are more “fair”.) To find where the log surfaces will intersect on the vertical chalklines, you could position the two logs over each other and then use a scriber, or a line-projecting laser, or a plumb-bob. But accurately positioning 1-ton logs over each other is a time-consuming, hair-tearing-out hassle. And it has to be repeated for every pair of logs you will be connecting. So I came up with a portable story-board (foam core) to find the surface intersection points. No log has to be leveled lengthwise. The story board is pinned to the HP of one of the logs and then that log’s surface is projected onto it, and drawn. Next, pin the story board to the HP of the mating log, and project it’s surface and draw it. The log surface projections will cross each other on the story-board and these are the points we are looking for. They are easily transferred from the storyboard back onto the logs.

This gives us 3 known points marked on the log for each joinery plane: 2 hinge points plus 1 surface-point. I recommend you use the MDF horse collar, sling it over the log so it goes through the 3 points, and then trace it, score the line, and cut. Someone truly skilled with a flexy rule can join the 3 points without using the MDF horse collar, but I don’t think many timber framers have that skill yet—it takes practice to get accuracy.

The 3-point method and portable storyboard produces lofting benefits and lofting results . . . without lofting. The logs to be joined can be sitting in different corners of the yard, or even in different hemispheres, if you don’t mind mailing the portable story board. I decided to demonstrate this technique at Burlington because I know that some timber framers loft, and I figured that they might want to consider the portable storyboard idea for their own purposes. The portable storyboard solves lofting problems that come with timbers (and logs) that are heavy, long, awkward, unstable, numerous, or distant from each other. You just carry the information on the storyboard from timber to timber, without having to carry (or position) any timbers. It could even be used to 'loft' pieces that cannot be moved—say if one piece is already part of a structure.

Please note that 3-point layout produces joinery planes that are probably not at 90° to each other in a joint. This isn’t a problem: I’m just saying that only the 2-point-and-angle layout produce joints that are necessarily 90°. With the 3-point method I never even measure the angles of the joinery planes, because I don’t need that information. The joints are equally tight with both layout methods.