188宝金博页面版

Page 1 of 2 Easy Bowls Part 2 Introduction This is Part 2 of a 2 part session about how we can successfully turn all those bits of green or wet wood that we acquire into bowls, dishes, platters etc. If we attempt to dry large chunks ourselves they will probably split. Commercial timber merchants convert hardwoods soon after felling, then either stack and season it outside for years or dry it in computerised kilns which monitor the temperature and humidity in a different way for each type of wood. Most of us don't have access to such fancy kit so we have to adopt another approach. Part 1 and after In Part 1, which was at our January meeting, we took a piece of wet spalted beech and turned a plate or shallow dish. I also showed you a shallow bowl that I had turned as a practise piece from the same wood. We weighed them and wrote the weight and date on the wood then I took them home and put them under the bench in the workshop. Every so often I re-weighed and dated them. When they were a constant weight under the bench I moved them to a higher and drier position in the workshop. This is how their weight changed :- Date Bowl Plate 8 January 938g 11 January 502g 17 January 496g 9 February 704g 386g 19 February 646g 366g 1 March 646g 364g 11 March 626g 354g 6 June 616g 352g As wood dries it shrinks, BUT it does not shrink evenly all over, and the amount of shrinkage varies greatly between different types of wood. Wood shrinks very little along the grain but much more across the grain. This means that a round bowl made in the conventional way from a side grain blank will go oval as it dries. The bowl now measures 222mm along the grain and 217mm across the grain. When we rough-turned these items we reduced the thickness, we also removed the middle of the bowl. This means that there is much less wood to dry, less chance of stresses building up and the wood has more freedom to move instead of cracking. If the wood has the sort of interesting grain patterns that we like then this is likely to cause problems as it dries, with more distortion than a straight grained piece. Part 2 Using the same chuck and jaws as for the rough turning, re-mount the piece on the original spigot aligning jaw 1 with the pencil marks. If the base and spigot have distorted while drying try to mount the piece as evenly as possible. Tighten the chuck just enough to hold the piece firmly. Using a bowl gouge, re-cut the rim so that it runs true, starting with light cuts. If the piece is very distorted, take a couple of light cuts from rim to base inside. On the base, inside the bowl, mark and cut a shallow recess to fit your chuck jaws. This only needs to be about 3mm (1/8”) deep.