Hi Guys,

Quite some time ago I had a need to sharpen a countersink, Today I needed to sharpen another ! Back then I made a jig to hold the countersink while rotating it against the grinding wheel. Today I've modified the jig slightly in order to improve the grinding shape.

03-08-2020-06.jpg

This is the sort of countersink I've been sharpening. This one has just been ground using the jig.

03-08-2020-01.JPG

This is the setup. The sharpening jig is clamped to the grinder table at the correct angle, in this case 41 degrees.

03-08-2020-04.jpg 03-08-2020-03.jpg

The workpiece is held in a drill chuck and rotated through 360 degrees.

03-08-2020-05.JPG 03-08-2020-07.JPG 03-08-2020-08.jpg

It isn't always realised that the countersinks are not actually round but are tapered cones. The countersink is fed forward into the grinding wheel by a thread. In this case a 1.25 mm pitch screw moving the whole countersink, chuck and shaft forwards as the chuck is rotated.

This gives the countersink a smooth tapered cone and a sharp cutting edge. The cone providing relief behind the cutting edge in a similar manner to a lathe tool.
Attached Images




Read the full thread at metalworkforums.com...