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"Line Rule" methods of layout for Timber and Log  RSS feed

 
Jay C. White Cloud
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Hello Folks,

This and related methods of log and timber layout have come up many times over the last few years. I have been asked several times to focus a post topic on this subject demonstrating methods and opening it to conversation and questions. Here is a the first of what I hope will be an ongoing reference for folks to come to when seeking assistance. I have chosen one of possibly the oldest methods know other than "direct lofting" and "scribe rule" methods. Some of this information is new, some isn't, yet now it, at least, is in one location here at Permies for folks to reference.

Of all the layout modalities found through the ages that have been employed on log and timber structures of all kinds from nautical and shrines to domestic, civil and agronomic...line rule seems to be the most used and universal of systems. Asian seems to present as the apex of this method for the last 4000 years where it is still the dominant form of layout for timber and other wood structure. In Korea as just one example, 자연석 주초놓기와 기둥세우기 (best I can do in phonetic pronunciation: jayeonseog juchonohgiwa gidungse-ugi) is the what would be described as dropping and building posts to stone plinths. This literally representing a foundational element of line layout use. This method of line rule use in Korean foundation layout 그렝이질 (geuleng-ijil) demonstrates just one of the many applications that no other method of layout on timber does as well as this one.

Whether dealing with dimensional timbers, round, tapered, or otherwise, this ancient method serves well. It even fits into the foundational element of architectural design as often we are designing to the "ideal" centralized element inside a structural member...not the face of that member. Therefore, whether a building is perfectly square...or...some other shape really has no bearing on the modality. that is the uniqueness and wonder that is "line rule."

We now know most timber frames had been (and probably are still) built between the Middle East and Asia, and only a very small portion globally are, or ever have been built in America and Europe (other than the “post and lintel” Neolithic structures of the Americas First Nations People.) I know that is saying a lot, considering the quantity, variety, and beauty of the frames here in America and Europe, however, timber framing has been practiced between the Nile Valley and Asia for thousands of years. There is Neolithic evidence that timber framing moved east thousands of years before it moved North and West into Europe. Timber framing appears to have reached a zenith of complexity in Asia, using square trunnel pass through and “dead,” pegging methods and the “center line” or simply “line” method of layout, (still the most common form practiced today globally,) before frames in Europe moved much past post and fork methodology.

I would also add a little more about “lay out” techniques, as they are as important in defining the different forms of timber framing as are the terms, “post and beam” vs. “post and lintel.” Historically, “scribe rule,” and “line rule” are the two oldest (and still practiced,) methods of laying out a timber for joinery. In Asia, where oblique (diagonal) bracing is used in only rare and specific application, “line rule,” is still the dominant form of layout, there by being the most practiced today and historically. “Edge Rule,” (laying out off a selected edge/plane to a conceptual “perfect” timber inside,) and/or “Mill Rule,” (selecting the edge/plane of a near perfectly milled timber,) are both rather new techniques that have been around for less than 250, (maybe 300) years. It evolved after the production of powered sawmills.

As we explore the elements of layout, we must go beyond what is here in North America, and look at the vernacular archetypes of timber craft, which seems to be, like so much of civilization rooted in the Middle East? From all that I have gleaned from study, and all that I continue to discover, the craft of the Timberwright/carpenter went East from the Nile Valley thousands of years before it went West and North into Europe. There it flourished into forms of great beauty and complexity in Shang Dynasty, (1700 BCE,) while the rest of the world was still in, or just coming out of Neolithic periods. The layout methods there, still in use today as one of the oldest methods in the world, are “line layout.” I have not been able to gather yet exactly when, (we may never know,) this method evolved from the progenitor of “edge rule.” In as such, the two methods are often used in concert with each other, as the “line,” forms a single imaginary point inside the timber, that all joinery is referenced from, while a reference edge or plan, is used to execute visualization of the individual joints. Like many with this interest, every day I read and think a little bit more about this craft, and each day I have more questions. Why is the oldest and most used method of layout, still confined primarily to the Eastern Cultures? Why did not the Europeans move to the same logical conclusion about layout? Why did the Saxon cultures develop such elaborate and labor intensive, scribing techniques, instead of the use of templates and reference lines/points? Was this because of the development of paper or just the extra millenia that made the difference? Even the Pacific Northwest First Nations people used a “line and template,” method for layout that predates Columbus and is our own vernacular form of timber framing here in North America. Did this indigenous culture develop this on their own or because of trade with the East over the millenia, as is now being accepted by more anthropologists/historians? The Pacific Northwest and the Ainu People of Northern Japan and Eastern Russia have such similarities as to indicate they have a common ancestor. Did these methods come with them?

As a Timberwright, I was taught the foundational methods of layout first...and of the three primary methods the oldest..."Scribe Rule."

Scribe rule is the archetype modality, still used today, and probably the oldest method; often considered by many, especially in Europe, to be the best method. Some even claim it is overall the fastest, which is debatably from a "side by side" comparison, yet in the hands of a Master Timberwright well versed in the method...it is quick and very accurate. It also allows for the use of materials that are not uniform in nature, as does "line rule."

This brings us to the next oldest method of layout..."Line Rule" or "Center Line Rule. The exact historical chronology of this method is yet to be uncovered but we know that it has been used throughout Asia for well over 4000 years, and perhaps longer. This method is sometimes used in concert with Scribe Rule.

The next, becoming the focal point method for many modern day timber framers (regrettably in my opinion) is Edge Rule or sometimes called Mill Rule. Edge rule grew out of the logic of pre-Industrial Revolution standardization and "dumbing down" the process of building with timbers. It may have even started in the commercial shipyards of the era, yet did not take off there as it did in other timber building crafts. It does allow for a simplistic and rapid approach to building timber structures...especially for the young culture that North America was during its expansion into the Western lands. It allows for, with some accuracy, the formation of a frame from generally uniform materials and a standardization of the "ideal timber inside" a given Cant of lumber. This allows for a uniform layout and cutting of joints.

Oddly enough, many in the past and today will use an offset method of line layout from what is called the reference face or edge. This method, though not "center lined" stops being "edge rule" and once again becomes "line rule," layout.

Here is a friend/student about to access a timber for layout using line rule. They are thinking about the design of the frame; the placement of the member; does there need to be a reference edge or face selected; and whether the "soul line" lines (the one inside the timber) is actually centered or offset.


Now that the above decisions have been made the timber is leveled and balanced to the location it rests on for "snapping and wrapping" layout lines.


Vertical Reference marks are created on the end then horizontal...



They primary tools of layout...an ink pot and bamboo pen....


Snapping a line...



View of a laid out end...


I will, in time and with questions, try to refine this entry to have additional information and detail.

Regards,

j










 
Hans Harker
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Thank you for the lesson. What i get from it is that the line rule is a way of marking the geometrical (near) center of the piece of timber for the purpose of getting points of reference for laying the timber out in a structure and for carving joints.

Although i noticed that the log in the pictures is narrower on one side but the line that is drawn goes straight along the 'straight' edge of the log rather than towards the middle of the narrower end of it. Does it contradict my 'geometrical center line' understanding of the line rule or is it done for a certain purpose.

What also interests me is what is the reason for marking the soul line in the last picture, is it to make some sort of measurement for some sort of calculation or is it just a visual aid.

 
Jay C. White Cloud
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Hey Voy...thanks for being the first to ask a question!....

I was born on the South Side of Chicago as my mother was passing through...(long story there)...Would love to help you figure out your future project goals...Send me a PM or email direct to discuss it...

Although i noticed that the log in the pictures is narrower on one side but the line that is drawn goes straight along the 'straight' edge of the log rather than towards the middle of the narrower end of it. Does it contradict my 'geometrical center line' understanding of the line rule or is it done for a certain purpose.


First I should help with some semantics...

When we walk through a forest we see trees....

Take one of these beautiful things down...with blessing I hope...and we have ourselves a..."Log."

Now if we cut those logs into sectional link we have..."Bolts."

Square up those Bolts by either milling or hand hewing and we have..."Cants."

Now Cants can be employed as they are or further shaped into what you see my friend working on; which is a..."Timber" (or what we kiddingly call "sticks" in our line of work...)

Now to your first question...

The 'surface lines' represent the 'soul line' inside the timber...The timber can be round, square, spiral, tapered or a just about any shape from an arch to perfectly square and that will not effect the 'soul line' of the timber. The 'soul line' can even run in and out of the timber like it would in say...an arched timber.

So...it will not..."contradict my 'geometrical center line' understanding"...or...it shouldn't in most applications...

What also interests me is what is the reason for marking the soul line in the last picture, is it to make some sort of measurement for some sort of calculation or is it just a visual aid.


In the last picture we see the end of the timber with what is often called..."the magic cross." Where the vertical and horizontal lines bisect is the 'soul line" inside the timber we are working on. This "cross" is formed mainly for the purpose of visualization, yet also it can facilitate that the layout is actually in alignment end for end and for "checking" that everything is plumb and/or level....

Thank you for such wonderful questions...This will help me in a short time to go back and edit the first post...

Regards,

j
 
Hans Harker
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Our first three kids were born when we lived on the South Side

Thanks for the 'vocabulary hints' It really does help.

Another question that pops in my head: wouldn't be more advantageous to mill a stick so the soul line goes through the pith?
 
Jay C. White Cloud
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Another good question Voy...

"Heart Center" (pith) is often the optimal choice for some timber members in a frame...Post for example. Yet, this is where the real craft of timber framing comes into play. The experienced Timberwright must know which species can do what and what "rules" must be follow pretty closely while others are much more..."gray." White Pine (the species in the Photo) is very forgiving and this small post is adequate to have a "out of center" or "drifted pith." Also there is the issue of milling and hewing...The better Timberwrights either do...or...oversee closely all their tree selecting and milling/hewing. As such, getting the best yield from a 'bolt' is often a dance of different give and takes...as is the case with this small post in the photo. This came from a large limb in the top of a very large (and old) White Pine 'wolf tree'...a tree that had actually be "called out" for toilet paper pulp because of the age and challenge it would be to contemporary (read low knowledge...little experience) sawyer...

Regards,

j
 
Hans Harker
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I went back to the Korean Hanok video you posted back in Nov and took a closer look at how they were preparing the bolts and it seems that great care was taken to align the soul line with the hart center. But then the joints they make later on top of the posts wouldn't be as strong otherwise i imagine.



 
Jay C. White Cloud
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...it seems that great care was taken to align the soul line with the hart center.... But then the joints they make later on top of the posts wouldn't be as strong otherwise i imagine....


Excellent Voy...

This is the subtleties that are timber framing...the rules are fluid...but...only if you understand them...

When working in round timbers that will form a frame...each bolt is taken individually for it's give characteristics. It is much easier...with the proper bolt...to 'start with' the soul line in the center of the working member. One the other end the same can be said, however, there it can also be adjusted to achieve other effects and characteristics within the working member and its joinery...

In the photos you shared we have a case where the soul line is 'heart center' to the timber. This is achieved by shaping the bolt to a standard size top and bottom which gives the illusion of taper to the wall, which indeed might even batter in 3 to 5 degrees...but this takes us into advanced systems that really go beyond the scope of this conversation...

Thanks for following along...

j

 
Hans Harker
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Jay, thank you yet again

I think i got the basic understanding of what line rule is now. Would you mind explaining scribe rule a lil bit?
 
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