Saturday, 15 March 2014

Nest concave tool

by Dick

We previously advocated soft fibre-board for making nest concaves, here. Up until now, we have made these by gluing together two layers of fibre-board to make a blank 25mm thick, then scooping out the concave on a lathe. Here we have a better idea.

The tool mounted above a blank, and the tool in action, right.
The cutting edges are bevelled at 30°


A friend of mine has made a tool to be used in a pillar drill. Setting the pillar drill to its slowest speed, 210 rpm, it does a nice job of very quickly excavating the concave, without creating clouds of carcinogenic dust.

The material of the blade is 3mm gauge plate.

It takes less than a minute to scoop out each concave.

Note: the diameter 100mm is intended for cutting material 25.4mm (1 inch) thick. For other thicknesses, assuming 2mm is left at the bottom, the diameters would be as in this table. A larger diameter means a shallower concave:

ThicknessDiameter
12191
12.7180
15152
18129
20118
22110
24104
25102
25.4101

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