Tuesday 24 November 2009

Construction - part three

Mike Griffiths (guest blogger) gets a little side tracked during his canoe construction.

The challenge of cutting out the five half planks of a lapstrake canoe from a sandwich of four sheets of marine ply looked daunting without a good working surface to support the job. The only existing work surfaces available for carpentry (my wife is not inclined to let me use the kitchen table) are an odd collection. They consist of a badly repaired Chinese copy of a “workmate”, a couple of adjustable trestles and a broken occasional table. The one unifying feature being that none of them are exactly the same height. I needed something to support the sheet material properly, set at a level suitable for sawing.





The initial plan was to use a couple of sheets of kitchen/bathroom grade chipboard (the green coloured variety) as the work-surface and to construct some arrangement of timber to support it. The serendipitous find of some cast iron legs holding a rotting plank in the damp corner of one of the barns changed the plan – I now had a base from which to construct a proper work bench. With a breakfast mug of tea in hand, I went through the timber stack to see if any combination of pieces gave me inspiration. A number of scenarios presented themselves while I drank my tea but in the end I settled for simplicity (and a slice of toast). Three timbers of similar thickness bolted to the iron legs with a narrow length of chipboard between two of them. I am not entirely sure what this valley arrangement is for but I definitely recall that the work-benches we used in woodwork class at school had them so they must be important. See! I did pick up something during those years of ‘durance vile’ at grammar school.






The result, as you can see from the pic, is unlikely to meet the approval of a master joiner and certainly not my old woodwork teacher but might, just, pass for an amateur canoe builder. At least it is robust – so robust in fact that it is just about impossible to move. I plan to rebate a channel between the two butted timbers and fill that with a slice of the same wood (to avoid losing small things down the gap) plus the wood needs belt sanding – oh and I will add a vice. Hmn – this is building into a project of it’s own. I have already spent the time I might otherwise have used to cut the canoe planks building this monster – so perhaps back to plan A – lay the chipboard on top of my new platform to get a smooth surface and get on with the cutting out.
So I came up with a simple, indirect way to screw the sheets to the (putative) workbench and “voila” I now have a strong, rigid and demountable table ready to saw my planks. (The back edge looks a bit curved in the picture but in fact it is nice and straight.)






In other exciting news – Paul rang up to say that he was posting me a container of wood dust. My wife Tracy was under-whelmed when she heard about this gift – thinks we have altogether too much dust as it is. The wood dust will be used to thicken the epoxy resin when it is used to form a fillet or when used as stopping in areas that will later be varnished. Mixed with this wood dust the result will be a closer colour match to the mahogany (okoume) faces of the marine plywood. In other areas colloidal silica can be used as a thickener for the epoxy resin.

Next time I will be back on track and doing some actual canoe building.

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