[QUOTE=Sam Price] David, the top has already been attached to the rims, and the glue is drying on the braces of the back, waiting to be profiled, then eventually glued on.[/QUOTE]
OK,
Leave the back with the braces unprofiled in the best place that you can monitor and control the humidity. Do the final brace profiling when you are in a position to finish closing the box. If the top/sides unit is keeping it's shape in the mould then there isn't a problem, but you can easily use a couple of scrap sticks in the upper and lower bouts to hold the shape with a small piece of cork between the ends and the sides - Poor mans/girls spreaders
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Dave White
De Faoite Stringed Instruments". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010