The TNT is my physical check after a visual check for the bevel. As in the video I have the blade perpendicular to my nail and don't go anywhere near the "half moon" (it's scary enough higher up on the nail). And I never used the TNT during the progression. Only when checking for a set bevel.
With only the blade weight the edge will "grab" or "drag" and feel as it it were cutting through the nail and you are about to lose your thumb. Of course it isn't and you don't, but it sure feels like it at the time.
I've never felt it "vibrate" and it doesn't feel "smooth". There is "resistance", "drag", and the feeling of "cutting" as if the edge were parting the nail, though it isn't actually cutting. Honestly, it's hard to describe, but unmistakable when you feel it. I would guess that a "vibrating" or "smooth" TNT result would mean the bevel was not set consistently, or that you are performing the test differently than I do.
With only the blade weight the edge will "grab" or "drag" and feel as it it were cutting through the nail and you are about to lose your thumb. Of course it isn't and you don't, but it sure feels like it at the time.
I've never felt it "vibrate" and it doesn't feel "smooth". There is "resistance", "drag", and the feeling of "cutting" as if the edge were parting the nail, though it isn't actually cutting. Honestly, it's hard to describe, but unmistakable when you feel it. I would guess that a "vibrating" or "smooth" TNT result would mean the bevel was not set consistently, or that you are performing the test differently than I do.