Thread: Bevel

I touched up my Dovo 6/8 and the shaves are par. I cleaned up an old Sim-mart, set the bevel and worked it up to the N-12K and it is an awesome shaver.

The touch-up and the hone from dull to shave ready were both 1st for me.

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

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.

Originally Posted by Amir

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.

No offense taken,,,

There are a couple of threads on here where the members took the actual measurements, and we did the angle calculations, the Average came out to be about 16° and very few razors fell out of the 15° - 17° range..

DE's and Multi blades use Coatings to adjust for their roughness, we use Strops and higher grit finishing

Secondary Bevels are old news and there are multitudes of threads on here about making and using them.. Think it through, there is ZERO difference in an edge that was done with a Secondary bevel, and the same edge done that way from the start

IE:
A bare steel edge on a 6/8 razor is say 16° now do a single layer of tape edge, same razor 16.64 ° secondary bevel at 17.28° now start from square one and do a 2 layer bevel it is still 17.28° the only difference is the ease of honing a partial bevel vs a full bevel which on most razors if negligible (all numbers are approximate)

BUT Please do not take my word for it, do the honing yourself to find out, it will teach you more by doing it then I can by saying it

I have never even come close to wearing any tape through, am I doing something wrong? I do change tape coming off the bevel setter and when I go into my polishing stones at about 8k and then again for the 12k.

Personally, I never wait until the tape wears through, usually replacing it when it shows wear. That really only happens on 1K and 4K. I also change tape at every grit change whether wear is apparent or not. From 8K on, little wear is apparent, although I will still change tape going from 8K to 12K.

Yeah, I only get tape wearing through on real junkers that need a lot of work, or when I use cheap tape, or both. I only mentioned the tape wearing through earlier in the thread to make the point that the extra spine height can be transitory.

James.

Kelly, I have also ben frustrated by a similar situation. I can hone the razor and strop it and check all the three tests, you mention. The edge is however very fragile or unstable. The razor is again pretty dull after one or two shaves. So I know that a shave is possible with my equipment but it does not last. I compared the edge on my razor with that of a feather DE blade and some other sharp blades under 60X magnification. I figure that it might be worthwhile to get a similar edge on my razor. I asked gssixgun about my suggestion and got a very informative answer. But he did not endorse the idea. My inquiry appears in this thread. Basically I have carried out my plan and expect to finish stropping tomorrow and then shave with the newly honed and stropped Razor. Hope you figure out why the edge does not last.

Originally Posted by Amir

I compared the edge on my razor with that of a feather DE blade and some other sharp blades under 60X magnification. I figure that it might be worthwhile to get a similar edge on my razor. I asked gssixgun about my suggestion and got a very informative answer. But he did not endorse the idea. .

Please do not put words in my mouth, Please re-read exactly what I wrote..

"A bare steel edge on a 6/8 razor is say 16° now do a single layer of tape edge, same razor 16.64 ° secondary bevel at 17.28° now start from square one and do a 2 layer bevel it is still 17.28°"

Let me explain that

A steeper bevel regardless of how it is achieved in theory creates a stronger edge, that however does not mean it will shave...

ps: go to the search box type in the term "Double Bevel" you will find threads stretching back 6+ years on SRP starting with Tim Zowada suggesting this technique for SR's, note that this is an old Knife and Tool trick that goes back even farther..

Originally Posted by gssixgun

Please do not put words in my mouth, Please re-read exactly what I wrote..

"A bare steel edge on a 6/8 razor is say 16° now do a single layer of tape edge, same razor 16.64 ° secondary bevel at 17.28° now start from square one and do a 2 layer bevel it is still 17.28°"

Let me explain that

A steeper bevel regardless of how it is achieved in theory creates a stronger edge, that however does not mean it will shave...

ps: go to the search box type in the term "Double Bevel" you will find threads stretching back 6+ years on SRP starting with Tim Zowada suggesting this technique for SR's, note that this is an old Knife and Tool trick that goes back even farther..

Thank you very much for your feedback. I used tape and have created a secondary bevel. The stropped razor nicely passed the HHT and other tests. Whether I now have a more stable edge remains to be seen. This is not a practical solution, even if it works. I have to leave the tape on which makes the razor look pretty unattractive. Meanwhile I will read the older threads on "Double Bevel". Thanks again for pointing those out to me.

Getting an edge similar to what is found on DE blades by hand honing is problematical. While such an edge may shave well, it won't be as stable as an edge formed by a machining process.

As regards double beveling, those edges are stronger, but they achieve their strength by being slightly less sharp than a single beveled edge. When the bevel angle is increased, the resulting edge is necessarily, as a function of geometry, less sharp. This difference is not necessarily meaningful in a shave, but it can be. An infinite series of double bevels results in a dull edge.