Re: TurboPlane, Safe-T-Planer - Powering through plate carving
Originally Posted by
Graham McDonald
I have always been puzzled by the idea of carving the inside first. Roger Siminoff recommended that in the first edition of his mandolin building book and the only explanation I could come up with is that it is practical in a factory where the plates are carved with a pantograph router (or these days a CNC) from rectangular blocks of wood of consistent size. Then it makes sense to carve the inside first as the inside carving is supported by the uncarved outside and when carving the outside the plate can sit on the flat edges. For a one person hard-carving shop it makes much more sense to carve the outside first, get all those tricky curves right and then do the thicknessing from the inside. A cradle will be needed to support the outside while the inside is being worked on the it allows much more control of the outside shape and then the graduations.
I start by drawing a half outline and the lengthways arch on a large sheet of heavy paper. Then add in several cross-sections which will allow you to plot out contour lines. That allows drilling holes along those contour lines to the correct depth and removing most of the wood between the holes with an Arbortech. A 60grit sanding disk in the drill press refines the shape pretty well. Here is the contour plan for a guitar bodied octave mandolin I made last year. The holes re always conservatively drilled, usually .5mm shallower, to allow for the unexpected.
Ever made a cradle with expanding foam? I have for other items of similar thickness just by putting a piece of garbage bag over the item then using the foam over the bag. I take a rasp and level it off after it dries. I would try it on the bag first to make sure it doesn't eat through it. Not all plastics are made equal, but foam makes a nice quick cradle. I still wouldn't put a ton of pressure on the item though, the foam is hard but not completely rigid. Just a thought.
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