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A Rough Guide to Timber Conversion Charles Willment, local saw-miller and native hardwood specialist, explains some milling basics How you convert a tree into timber depends on three main factors - the species, the intended use and the quality of the tree. The bigger, straighter and clearer the tree, the more options you have. What makes a good tree? Nice and straight, no low branches, dead knots or metal. For sawmill conversion there are three main methods: Cut the tree ‘through and through’: this is the quickest and most efficient way of conversion, producing the widest boards which can be edged or left with bark on. Boards are re-stacked in-stick, the traditional method for timber to be seasoned for future use. Cut to dimension: the log is rotated as boards of varying widths (with one square edge) are taken off and when square, the ‘cant’ is sawn to dimension (4” x 2”, 6” x 3” etc) ready for use (green oak building, fencing) or left as a beam. (a) Quarter-sawn and (b) true quarter-sawn: (a) the tree is cut into quarters which are then cut on the square but rotated after each cut. (b) the tree is cut into quarters and then cut on the diagonal. In both these methods all boards show ‘figure’ (the growth rings, on the end of the boards, are less than 45 degrees to the face). This is the most ‘stable’ timber and is less likely to twist or bow in drying, but many boards are narrow, wastage is high and production is slow due to the extra handling involved. Only really worth the aggravation if the tree is over 3ft diameter, of very high quality, and if you really are prepared to saw up just one trunk in a whole day! First quality anything: Through and through, board thickness to suit end use (7/8”, 1”, 11/4”, 11/2”, 2” and 3”). Air drying: leave the bark on. Kiln drying: edge it; get more in the kiln, unless you like the waney look. Second grade oak, chestnut, softwoods, elm: General building stock - 6” x 1”, 4” x 2”, 3” x 3”, 4” x 4”, 6” x 6” etc. or just beam it up Scotty! Second grade everything else or worse: Usually 1” and 2” boards and some 3” or 4” slabs - hey, start a new craze - it worked for decking (God bless Alan Titchmarsh). People have tried tried loads of different ideas and timbers. It all gets used for something eventually. Above all, think carefully about the final use before you decide on cutting, and listen to the saw miller. And be prepared to change your mind halfway through the log when you find it is hollow, or full of metal/concrete or is so shaken it falls to pieces once ‘opened’. (All planked timber is air dried for about 1 year for each inch of thickness, bringing the moisture content down to about 20%. The timber is then ready for exterior use or kiln drying for interior use.) For those of you who would like to learn more about tree and timber grading, selection, cutting and drying, I will be holding some one-day courses. Costs £10 a head, bring your own packed lunch, we will supply tea, coffee etc, dress accordingly. Time will be spent in both the sawmill yard and surrounding woodland. Dates to be confirmed subject to interest. Contact: Charles Willment, Treespanner Timber, Tel: 01342 871529, Mobile: 07713 083625, Email: charles.willment@virgin.net Website: www.treespanner.co.uk |
 Charlie Willment's trusty mobile sawmill |
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