Countersinks- Single flute/Zero Flute....?

Man, I must have awakened grumpy or maybe I'm just a grumpy old man.

In the above videos I found that the first one "1005...." the operator didn't use a precise setup but he ground the proper cutting edge relief. In the second video, the operator precisely ground away all the relief, even changed the angle of the taper ever so slightly. From my experience in the machine shop of Jostens years ago sharpening their HSS pantograph cutters, once the taper angle has been carefully established from the cutting edge or a known standard, the sharpening passes start with removing the material that trails the cutting edge. As the cutter material is rotated against the wheel, usually a cup wheel, the rotation stops as soon as the back of the cutting edge is reached. This is repeated until the cutting edge has been restored and with proper relief behind it.

Is there some advantage to having no cutting relief behind the edge? In my experience, whether it's a drill, mill, countersink or something else, a bit of draft is necessary. Am I missing something?
DanK
 
Dan Krager said:
Man, I must have awakened grumpy or maybe I'm just a grumpy old man.

In the above videos I found that the first one "1005...." the operator didn't use a precise setup but he ground the proper cutting edge relief. In the second video, the operator precisely ground away all the relief, even changed the angle of the taper ever so slightly. From my experience in the machine shop of Jostens years ago sharpening their HSS pantograph cutters, once the taper angle has been carefully established from the cutting edge or a known standard, the sharpening passes start with removing the material that trails the cutting edge. As the cutter material is rotated against the wheel, usually a cup wheel, the rotation stops as soon as the back of the cutting edge is reached. This is repeated until the cutting edge has been restored and with proper relief behind it.

Is there some advantage to having no cutting relief behind the edge? In my experience, whether it's a drill, mill, countersink or something else, a bit of draft is necessary. Am I missing something?
DanK
Click to expand...
I agree. The main point of cutting edge relief was lost in both videos. One of the comments called him out for this. I wonder if you can get decent results by following the "thin blue line" method: blue the surface and grind like a twist drill, just leaving a thin blue line at the cutting edge.
 
Yes, that works, ericc. How thin is a personal reaction to how long one wants the edge to last in the material being cut.
DanK
 
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