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Author Topic: Cross Sills
Ken Hume
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Post Cross Sills
on: April 15, 2015, 09:10
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Spring has now arrived and with the return of the sun the woods resound with the sound of birdsong accompanied by the ringing of axes on timber.

Andrew Jarvis has decided to try his hand at hewing now that his winter work of hedge laying and thatching spar making and woodland maintenance work has drawn to a close. The first task was to buck (cut to length) two reasonably straight lengths of larch log to produce two cross sills. One of these logs had quite a large knot near the top end of the log and so this was surgically removed with the scoring axe to ease hewing.

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The cross sill logs were hewn using the Kent pattern hewing axe to remove the heavy wood followed by cleanup and smoothing by The Wetterlings broad axe.

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It was decided to leave cruck blade no 6 in place to provide a sound full length platform to hew the first cross sill and experience has now shown that this is a good safe practice.

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It is important at all times to ensure that the swing of the axe and a deflection of same is kept well away form the lower limbs and of course toe tector boots must be worn at all times. We have now determined that although the Wetterlings broad axe can be used for heavy wood removal that this results in much higher forces being applied to the arms and wrists when compared with the long handled Kent pattern hewing axe and so the risk of sustaining repetitive strain injury to the hewer will be higher. It is also necessary to provide greater forward motive power to achieve the same cutting effort as with the much heavier long handled (36") Kent pattern axe where it is mainly the gravitational fall of the axe that performs the cutting action leaving the hewers arms free to simply guide rather than force the cutting action.

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The two cross sills are seen below with one complete and one partially completed log. Providing the log is turned onto the first flat face and the same hewing position is adopted then the next face to be hewn will be exactly at 90 degrees from the first face and thus no instruments (string lines, levels or measuring equipment) other than the eye are really needed to convert a log.

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The presence and extent of heart / sapwood across the full section of the log is clearly obvious and though a finish hewn log might outwardly appear to contain large amounts of sapwood the cross section reveals that this is actually relatively small in percentage terms.

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The fourth face of cross sill no 2 is scored by Andrew ready for hewing the final finished face of this 17ft beam

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Finished cross sills 1 & 2. The presence of sapwood and wane gives the sills the appearance of being wavy whereas they are actually quite straight.

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The cross sill surfaces were given a final lick using the drawknife to flatten and remove any raised areas together with making surfaces smoother and safer to handle (splinters).

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The log pile is now diminishing and the heavy duty reinforced blue plastic sheet placed under the logs to help prevent rot and insect attack is now more obvious. Bark removal is recommended to reduce long horn beetle grub damage to the sap wood though since most of this will be hewn off this is not really a major concern. Two tall skinny larch poles have been peeled to be kept for use as gin poles to raise the cruck frames.

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The Oxfordshire Woodland Group welcomes providing opportunities for those persons aspiring to work in the woods and / or gain experience in timber conversion and cruck timber-frame building. Please get in touch.

Ken Hume - Trustee - Oxfordshire Woodland Group

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