We have the Bedroom Bastard Valley installed and looking great. After months of cutting in the shop, based off of math, it sure is inspiring to see that all of our hard work, and endless double checking, was worth it. Please notice how the bastard valley sits tight on all 5 bearing points; it is hard to even explain how difficult and precise this system was to fabricate.
So, having installed all of the posts around the stairway, it was time to install the collar ties, knee braces, and base posts that complete the two bastard valley bents. We discussed putting the entire bent together and flying the whole thing in at once, but, since we don’t have a crane in the yard (just a priceless antique Grad-All), we needed to install everything piece by piece.
As you can see in the video, this necessitated rigging up a system to float the knee brace and collar tie for the base post installation. This worked beautifully and as expected, which is nice. We may, during the actual raising, when we have a crane, still put the whole bent together but it is nice to know that we can efficiently piece everything together as well.
After isolating the location of the main bearing post, a 24″ diameter, 18′ tall Douglas Fir, we could lay out the location of the “D” logs that will hold up the bastard valleys around the stairway opening.
As you can see from the video, we used four string lines to find the center of the main bearing post; Old Glory is what we call him. Because the layout of the timber frame is based off of a mathematical grid, and because Old Glory holds up 9 different timbers, this allowed us to pull both main axis ridge lines as well as the two bastard valley center lines; where they all intersect is the center of Old Glory.
We placed a large wood pad where Old Glory goes and then used a transit to both level it and to calculate how long to cut Old Glory for installation. We placed the pad below the final post bottom location so that, once the entire frame was together, we could use a transit to mark the actual cutting length of OG.
The interior “D” log posts, so called because they have a flat face milled on one side of them, are attached to the floor system with traditional mortice and tenon joinery. As you can see in the video, the flat faces of the posts carry the plane of the stairway opening up to the ceiling which ensures that no part of the posts intrude into the stairway.
To appreciate the complexity of the layout, keep in mind that the “D” posts must be cut so that they place the top of the bastard valley at the correct elevation along it’s length. While we had theo lines placed on the posts during the bent layout in the shop, we still used a transit to ensure that the floor was at the correct elevation and that we could trust the theo lines from before. Of course, at this point, we won’t know if we did our math correctly until we actually install the bastard valleys in a few days. And that is why we say that the layout guy is at the sharp end of the spear; if the pencil line is wrong, then all the expert cutting in the world won’t save you.
I am continually amazed by what the craftsmen that went before us were able to accomplish with what we would, today, consider to be rudimentary tools. Though, Homo Sapiens Sapiens has been around for at least 50,000 years and it isn’t hard to imagine, with that kind of time, that engineering and construction methods developed by the ancients were every bit as “magical” as what we consider mundane today. Gravity always pulls a plumb bob straight down, and water always levels itself, and the precession of the equinox is as consistent and reliable clock as any we have developed so why is it so hard to imagine that humans as intelligent as us could accomplish feats beyond our comprehension?
I have been reading a fantastic book that goes into some depth about the precision and craftsmanship of some of the oldest structures known to man and I get the peculiar feeling that humans have forgotten more knowledge than we can even comprehend. I am all proud about being capable enough of a craftsman to fabricate these bastard valleys and then I meditate for a moment about the stone work of Machu Picchu, or the incredible astronomical precision of the layout of the Valley of the Kings, or the ability to move and place 200 ton rocks, or the vision and drive necessary to even design such monumental constructs and I laugh to myself and am reminded of my pitifully small place in the universe.
The Fingerprints of the Gods, by Graham Hancock is the book, if anyone is interested
This video shows the completed bastard crotch system right before we disassembled it. You can see that all of the jack rafters and purlins have been cut into the bastard valleys and that the backing cuts on the bastard valleys have been cut as well.
Rather than mathematically calculating the backing cuts and then getting them laid out on a tapered octagon, we made a jig that allowed us to run a flush cut saw in plane with the top of the purlins/rafters and then cleaning up the remainder with a Fein tool and a sawz-all. This method worked very well and we were glad we didn’t try to lay the cuts out beforehand.
THis was the last major in-shop setup for a bit as now our attentions would be turned to raising the structure outside; this will allow us to cut all of the posts into the floor system and was necessary so that we could ship as complete as possible system. Our underlying goal always has been to minimize spent on site during the raising and it became obvious that standing the structure at the shop was a critical step for us to maximize efficiency on site (over 2500 miles from home)
This video is a compilation showing the fabrication and initial assembly of the bastard crotch system. Having already cut both bastard valleys into their respective bent systems, we now needed to cut in the purlins and the jack rafters. Sice the bastard valleys are tapered octagons, it was impossible to cut these according to math (square ruling) and so scribing was our solution.
To scribe correctly, all of the components must be placed into space exactly where their final configuration is and then we use scribes (basically large compasses with leveling bubbles) to transfer marks from one piece to another and then we cut to those lines.
Placing the bastard valleys in space was not an easy endeavor and we discussed a few options before we settled on what we ended up doing. Using the computer, we were able to determine the proper elevation for tha bastard valley at the center line of each bearing point. Using this information, we were able to construct a cribbing system of walls that would hold the valleys at the proper position, both in elevation and in plan. It took a couple of days to fine tune and perfect the placement, but, one we had it perfect, we were ready to place and cut in the purlins.
As the valleys taper towards the peak, we thought it would be a nice touch to make each higher purlin smaller in size, so everything reduces in size as it gets higher and makes for a space that seems higher and more soaring than it actually is. Perfect, really, as high soaring ceiling are tremendously inefficient and we really quite dislike them.
This compilation of videos shows the process of fabricating the Bastard Bent, of which we needed two. The video depicts the initial setup, fabricating the second setup, and the complete system sitting in space.
This animation shows the configuration of the two, mirror imaged, bastard valley bents. Each bent is comprised of a 35′ tapered (from 15″ down to 12″) octagonal bastard valley, one 21″ diameter “pacman” butt log post, two 12″ diameter interior posts (both with flats cut on them 7 degrees off of the centerline plane. These flats define the stairway corridor and flush out with the floor beams below), a small intermediate post, a tapered knee brace (10,000 lbs of compression at the log end!), and a horizontal tie beam. The Old Glory main peak log post is not shown as the bastard valley actually sits on the ridges at the peak, which, in turn, sit on the log post.
To fabricate the bent, we first isolated differences in elevation between the centerlines of each of the posts and used these to generate a centerline plot of the system which we could lay out on the floor. Using lasers allowed us to set the bastard valley in space and then place the posts above the valley and in space as well. Once everything is in space (this phrase describes the process of placing all the timbers in a particular system on an imaginary center line plane, perfectly level and plumb over their specific locations. The utmost care must be used when placing timbers in space as any deviation from perfect here will send waves of imprecision through the entire fabrication).
Once the posts have been scribed into the valley and the entire system is place back in space, we can then place the intermediate timbers (tie, small post, and knee brace) in space above the bent and then scribe them into the system.
As this timber frame design has so much interconnectivity, especially at the main peak, where 10 bearing points all center out at one single center line, the degree of precision required to ensure that all of the various systems fabricated in isolation based off of the computer theoretical (theo) perfect actually go together correctly is extreme. A small error (we live in the world of 1/32″‘s for example) can propagate through a timber frame and cause endless deviations from theo. One can never let their guard down and we endlessly check each others’ layout before cutting.
Here is a compilation of some videos I took during the fabrication of the Kitchen Ridge System. You will see the component parts as well as during and after footage of the assembly process. I am happy to answer any questions you may have after you have viewed the video.