How deep should the countersunk holes be when preparing brake lining for rivets?
Just enough for the head to clear the surface. Between 1/32" and 1/16". Don't use an angled countersink. If you don't have a flat countersink buy a cheap angled countersink and grind the angle flat then sharpen it using a Dremel Tool. Jim Patrick
Here is a crude drawing of a modified countersunk bit which, if sharpened properly, can be used to counter sink holes in all transmission or brake bands used on the Model T. If I am not mistaken, the cutting diameter should be about 3/16", or the diameter of the head of your rivets.