Countersink gage

[mklotz]

Thanks. I just hope that the Chinese manufacturers of Robertson wood screws know this, and have made them accordingly. More seriously, I don't think that I have ever seen a countersink bit marked with a specific angle and I don't remember anyone saying "change out all the countersink bits", when we changed from Imperial to Metric. You really have to wonder why a committee chose 82 degrees when they created the newer, now obsolete in most of the world, Unified system.

I asked the question of the Canadians on the HSM forum and they all agree that Robertson is 82 deg. One of them cited the Robertson webpage and says it's confirmed there. You can read the thread here...

Question for our Canadian cousins

Not all countersinks may have the angle stamped on them but they are definitely advertised by included angle. Here are just two examples...

6 Flute Chatterless Countersinks

https://www.mscdirect.com/browse/tn/...navid=12106118

Yes, the choice of 82 degrees is just another of the idiocies of the inferial system. Like number and letter drills and a plethora of upside-down wire and sheet "standards", it typifies the Usonian reluctance to adopt sensible, world-wide standardizations. Perhaps it's all for the best. If Usonians adopted the metric system they'd have two systems they don't understand.