Laying out on timbers with a lot of wane

[canopy]

I am working with timbers that have several inches of wane sometimes on more than one side. In these cases it doesn't seem practical to put a square on the timber and pencil line to it as there is a gap over the wane with nothing accurate to follow. Are there any good tricks to produce accurate layout lines on such timbers?

[Dave Shepard]

You can use snap line square rule. Do you have Jack Sobon's "Build a Classic Timber Framed House"? It is described in detail in there. It may be in other books, but that is the only one I have explaining it. I work with a lot of waney, twisted, hewn or otherwise non-cooperative timbers, and snap lines work well for me. I'll try to give you a brief over-view of the process.

Start by leveling your timber. Pick your best edge and best face. Let's say you are using a 2"/2" layout for this example. I have a 2" wide piece of locust that I planed down very accurately which is my gauge. I made a bunch of other widths for different joints. I hold a 2' level across the end of the timber, and I put the gauge on top of the level. I move the gauge and level up and down until it looks like the top is lined up with the top plane of the timber. If you are working nice square sawn timbers, this may not really be necessary. Once I am happy with the location of the gauge, I remove the level and strike a line with a pencil underneath it. I repeat this process in the plumb orientation on the reference face side of the timber. Do the same on the other end and connect the lines from end to end with a chalkline. Now you can lay out all of your joinery using a framing square on the chalk line. You may have to eye ball across some of the wane, but this isn't too difficult.

[Jay C. White Cloud]

Jack's method is a take off on traditional "line rule," sometimes now call "center line layout."  It has been around for almost as long as "scribe rule."  James Mitchell has two books that teach the basics. 

The Craft of Modular Post & Beam
Master's Guide to Timber Framing

And you can find it in the "The Complete japanese Joinery" book, but it is a little complicated and there are typos.

Here is a web example, I could find more...but this should get you going.  ;D

http://www16.ocn.ne.jp/~ikgroup/kentikurei/gijyutu.html

[canopy]

I have Jack's book and finally found the info under "Layout on Hand-Hewn Timbers" which is just a mere page with one figure I most likely skipped over the first time I read the book due to the obscure title. I wouldn't have thought to place the chalk line 1.5" inside but immediately see the genius of it plus how to do the alignment. That's definitely a very valuable page.

There is another bit in the book about laying out a post with some wane. The idea is to eyeball the framing square over the gap to align it; seems a bit difficult/error prone but may give that a try. But I'm pretty sold on the line rule since the timbers not only have some wane, but often other imperfections.

As for the Japanese layout photos, wow wow wow. Being able to intersect two oval logs perfectly like that is a skill set I'd love to have. I am waiting for your book.

[Jay C. White Cloud]

Hey Paul,

I'm trying to catch up but just landed two more timber framing jobs and a third today in Massachusetts...plus trying to finish building my own house.  I know, excuses, but I will get something on the forum to at least help you out within the next week.  We have some layout to do so I will take a few shots of the process we call "snapping and wrapping a timber."  First step is start thinking of your timber frames as simple single line drawings...just single lines.  With traditional line rule you are building to a single point inside the timber, and everything radiates from there.

more soon to come...

jay

[D L Bahler]

i have a full scale line layout on the ground right now for scribing. it is essentially like jay is talking, reducing the frame to single lines.
the technique i am using is to lay out line to represent points on timbers. some are centers and some are edges. there are rules determining which is which depending on the location and function.
then reference lines are snapped on the timber -because wood cannot be trusted to be straight
these reference lines are maybe 2 inches in from a corner or something like that. as such, they do not correspond with the layout lines. to account for this, we have to use 2 squares. one is set to the layout line and the other to the reference line on top of the timber. a plumb bob is then placed on the timber square at a certain spot, then at a corresponding spot on the lower square. if we line up at different inch marks on both squares, then we can align the timber to the middle. if we align at a point 2 inches different, then we are aligning the edge.

[D L Bahler]

more often we use a certain number as a rule. for example, we mark all layout lines from the same edge, then offset all of these lines 10 inches from the layout line. this is an easy way to do edge layouts. centers still require the use of 2 squares.

it is also important to level the timbers. they must be leveled with a line, not the timber edge.
our joints are housed and square. we don't scribe the contour of the timber, just the position.

[Dave Shepard]

I took a few pictures of laying out a hewn post using snap line square rule. I'll start another thread when I get them all uploaded, as I think it warrants it's own discussion.

[Jay C. White Cloud]

Hey Paul,

I'm going to post this here for you in a short form, but start a new thread for details, as you requested.  The new thread is called:

"Timber Frame Layout Methods"

I will make an entry on "line lay out methods," which should get you going with your "wane challenge."

D L's description is a wonderful example of "lofting methods" as they relate to "scribe rule."  and within scribe rule there are several related modalities, like "French scribe," "full scribe" "fit scribe" etc..  All are very similar and related.  One of the many timber framing interest I have is the history and/or movement of layout methods from one region to the next through human travel and trading.  One of the mysteries is why the "line layout" methods, which are less labor intensive, than "scribe rule," never evolved or "took hold," in Europe as they did in Asia.

We know through archaeological and literary evidence that the "scribe rule" methods of layout in timber wrighting are the most ancient and archetypal methods.  We often forget that ship building was probably some of the first ways timber wrighting was improved, advanced and then shared with other regions. We also know that during the pre-Shang dynasty of China (2800 BCE,) that "scribe rule," was abandoned for "line or center line rule" as the dominate lay out method throughout Asia, greatly advancing the complexity of the joinery and application; but decreasing the labor involved in the work. 

I know we have another conversation on this D L, but all evidence I can find indicates that my previous statements are true, timber framing moved East and evolved in complexity before it moved/evolved West into Europe.  Was modern man living in Europe (Switzerland-Germanic regions) at the same time as they live in the Middle East, absolutely, just as you claimed.  Did this region have as "advanced" timber craft as the other regions, I'm afraid there is no evidence, literary or archaeological, to defend that position.  If you could provide such, I would gladly consider it and examine further this evolution of the craft.

Now for the sake of clarity, I will go into detail on the new post for layout methods and reprint some of the above on the "Timber framing a discussion of History and pre history"

P.S. Sorry Dave S. I must have been writing this the same time you were, Please feel free to join the new thread I'm starting with your info, I look forward to it, wherever you post it.