Building a cruck timber frame

April 11, 2019

Building a cruck timber frame

Nels Christensen has an insatiable appetite for timber framing. He reminds me of a sheep dog with his boundless energy and pointed focus. If Nels doesn't have a customer project to work on he makes up his own.  

Hence, we have a few timber frame structures for sale here at Alaskan Viking Co. 

As a student of the trade, Nels has been steadily adding skills, styles, techniques, and specialty tools to his offering. A fascination for working with less than perfect timber and organic shapes led him to a cruck, or crook, framing workshop using the 'french scribe rule' technique. Upon his return to Alaska he was eager to build.

Here a few notes on the cruck frame and some snapshots of a couple concept sketches in my notebook.  I set out to write an article about this but I was getting pretty esoteric with descriptions of gravitropism and auxin-controlled growth reactions but I've since culled that. What I'm left with is really just a brief introduction.

timber frame cruck design notes

 design notes timber frame cruck building

building a timber frame cruck structure

Nels created a 3d model to fine tune the design and build from.

timber frame cruck frame 3d model design

timber frame cruck frame 3d model design

More from Nels:

Cruck Frame 2018:
The cruck frame is an eccentric expression of local mega flora. While some timberframes represent themselves through engineering prowess (see Hammerbeam or hawksdale angles in compound joinery) the humble cruck is an ode to timber sourcing and to the geologic forces to which forests on hillsides are subject.
These book-matched cruck blades began as curved trees grown on a hillside on Alaska's Kenai Peninsula. The elegant curves grew over many heavy snowfall seasons forming compression wood on the inside portion of the trunk. This wood forms particular dense annual rings on the inside (compressed) part of the curve with a higher lignin content which translates to an incredibly strong and dense lumber.

This frame is made of three pairs of cruck blades of book-matched local spruce. This particular timber frame's parti pris rests somewhere within a whale's rib cage and an inverted ships hull.



Step one was to find at least three large, naturally curved spruce trees to make the 'blades' of the three bents for the cruck frame. These curved timbers would become the main bones of this timber frame - transferring the weight of the roof down to the ground and giving the frame a lofty arched feel. Fortunately Nels had seen this coming a year before and asked a local logger/miller to set aside any large curved spruce trees he harvested. These wonky logs would usually be cut into firewood, but this year Dave kindly split them in half for Nels. 

naturally curved spruce beams timbers posts cruck blades
This blog post is to be continued . . 

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