Wabi-sabi’s First Timber Frame Bent Raising

by ziggy on August 30, 2011 -- 1 comment -- Follow

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Our freshly raised black walnut bent

In this post, I’m going to rewind back to June of this year when Wabi-sabi hoisted its first timber frame bent to vertical. (A “bent” is a cross-sectional assembly of posts and beams, part of the framing of a timber frame structure.) This particular bent was composed of two roundwood oak posts, and a hewn black walnut beam, with a span of around 18 feet. No small feat!

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Laying out and squaring up the bent on the foundation

This was our very first raising, so we had some kinks to work out, but ultimately, the raising was successful. The first step in raising the bent was moving the posts and beam into proper position on the foundation. That meant putting the whole thing together (and this case, pegging it on the ground), and leveling it. With the posts sitting on the sills and aimed towards their final destination, we worked towards level and square, testing the proper position of the posts with the 3-4-5 triangle rule.

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The post bottom end peg and hole

The posts, with a 1.5″ diamater hole drilled 2″ deep in their bottom ends, had small pegs inserted to be aimed at a hole in the sill. (Our sills, for the record, are an interesting fabrication of 2 2×12 treated pine boards nailed together. Because our foundation is so off level, it was a real trick to decide how to design a sill that could sit on a rocky urbanite surface, and spread the load of the post. This is the material that we had on hand, and that seemed “within tolerances”, as we like to say.)

Once we were happy with the position of the bent, we got some baby lifts and put bunks (chunks of wood) under the bent to get it a few degrees off the 0º mark.

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Gin pole with pulley

For this raising, a come along did the majority of the work. We rigged up a gin pole, with guy lines to keep it steady, and a pulley to give us a mechanical advantage in lifting the heavy weight of the bent off the ground. Our rigging line ran from a sling attached to the bent, through the pulley, and down to the come along. As Thomas cranked the come along, the rope would tighten, and then gradually pull the bent up and up.

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The come along and safety tieback posts

 

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Bent approaching 45º

Needless to say, we were quite nervous about the weight of the bent, and the engineering of our gin pole rig. When we first attempted the raising, our gin pole was having issues because of a faulty pulley that didn’t quite “pull”. Some tweaking here and there and we were set. For the final raising, we didn’t even have to get folks behind the bent with pike poles to push the bent up. The rigging with pulley, rope, and come along did all of the work.

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Almost there!

Of course, we had to get those bottom pegs into the sill holes, and that we did with the help of a giant persuader (think gigantic wooden mallet). The bent slipping into position was hugely gratifying!

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Our first fully raised bent

Once it was near vertical, we got a level and checked the plumb of the posts, and braced them. Viola! This bent raising was excellent practice for the big beast of a bent that was ahead of us…

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  • Nicofrog

    Why not use pieces of pipe,instead of maple dowels for the pegs at the bottom?

    In my experience,with any moisture,the maple dowels go soft after a few years allowing for slippage..
    but if you surround all with cob,keep it dry, and don’t have earthquakes in your
    area, I guess it really doesn’t matter does it?

    beautiful work,wish I could get these local hippie farmers away from their treated lumber pile!!And fiberglass insulation etc etc…

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