Which means making a thickness gauge. I found various ideas, most of them using a dial indicator, but on the other extreme gauges with just a moveable dowel carrying some scale. The one proposed by in Benedetto's book belongs in this class, but of course even simpler constructs can be imagined. And simple constructs with mechanical magnification of the movement. The most simple construction uses just a moveable dowel. That approach even has the advantage that the dowel can easily be replaced by a pencil in order to show the contours during work.
And this leaves a few questions:
- which precision do we actually need for which purpose (arched plates, plane plates and ribs)? Without using mechanical magnification obtaining better than 0.5 mm would become pretty hard, even if we consider an additional nonius scale. (we might replace the dowel by a screw?)
The precision of a typical indicator screw is a bit of overkill, isn't it? And not achievable in practice anyway? - what's the best measurement range for our purposes? min 1 mm, and max? 10 mm because dial indicators for that max thickness can be bought cheapest? Or do we need to be able to measure the thickness of the plate before carving?
- which depth of the opening are ideal for out purposes? 200 mm, 250 mm, 300 mm?
- which height of the open would be ideal?
