Double bevel on DE razor blades
Quote:
Originally Posted by
gssixgun
Sometimes putting things into real numbers help you realize that sooner or later you have to rub steel on rocks of some sort evenly until the two sides of the bevel meet into one very feaking sharp edge that hopefully is smooth on the face too.. :)
After quite a few people took the time to do quite a bit of measuring, we found razors that were shaving with bevel angles ranging from about 12 degrees to about 25 degrees.. these were shaving just fine
Then more measuring,, and you come up with and angle change for a 6/8 razor with one layer on 3M #700 Electrical tape of about .60 degrees.. This gives a huge margin of error to play with..
More measuring and testing found that the mean angle for razors by a large margin was about 16 degrees
More testing and measuring found that Taping a spine does in practice change the original angle but it changes it at such a small degree that it will take lifetimes to effect the edge..
Bad honing technique effects the bevel angle much more then taping a spine will, because of excessive spine wear :(
What did all that testing prove, Tape if you want, don't tape if you want, but if you use tape change it often and apply it evenly :p
Very interesting data on the wedge angle of good shaving razors ranging from 12 to 25 degrees. The 25 degree case is more like an axe and if I were skeptical, the inclination would be to think that it was a numerical error ( the true angle was 12.5 degrees ). Please do not be offended though, I am a newbie and the angles I have measures are around 15 degrees.
I also carefully examined the edges of the sharpest DE razor blades including Feather blades. Firstly, the bevel is far from a mirror finish. I am guessing that the last abrasive to tough it was 3k or coarser. The bevel is about .5mm wide. Secondly, about 1/4 or 1/3 of this bevel from the business end of the edge is beveled again. This part is smoother but still far from a mirror finish. Furthermore, the coarse straight line scratches are not removed by this finish but only toned down. My guess is that the purpose of the two bevels is to get a more stable edge. Anyway it seems that the DE blade manufacturers seem to have discovered long ago that a mirror finish edge does not make a better selling blade. The pyramid honing scheme taught by Lynn Abrams seems to make more sense to me now. Well, apart from the fact that it works.
I am now going to experiment with this secondary bevel on top of the one I have on my finished razor by taping the spine and giving it a few laps on Norton 8k stone to generate this second bevel.
Any feed back will be most appreciated.
PS If I knew the thickness of the Feather DE blade, I could compute the wedge angle, just out of curiosity.