Thread: Zowada Website - double bevel info. updated

I just used this method for the first time. I have a wedge (at least half of each side was in contact with the hone type of wedge) that I had been honing for hours starting weeks ago. It would polish up so nicely but the bevel was so wide that the edge was never getting sharp enough. So today I kept at it on the 4k until I thought it was as good as it was going to get there and then put a single piece of tape on the spine. From there, about 50 4k laps, 25 8k, 25 12k and this baby seems sharp! I have yet to shave test it, but the way it was mowing arm hair like never before I think it worked. The new bevel is about the size of what you would see on a new Dovo, and maybe a bit wider. So it is pretty narrow considering the first bevel. Looks good though. I'll probably shave with it tonight (whatever stubble I have left from testing other razors).

Originally Posted by Philadelph

I just used this method for the first time. I have a wedge (at least half of each side was in contact with the hone type of wedge) that I had been honing for hours starting weeks ago. It would polish up so nicely but the bevel was so wide that the edge was never getting sharp enough. So today I kept at it on the 4k until I thought it was as good as it was going to get there and then put a single piece of tape on the spine. From there, about 50 4k laps, 25 8k, 25 12k and this baby seems sharp! I have yet to shave test it, but the way it was mowing arm hair like never before I think it worked. The new bevel is about the size of what you would see on a new Dovo, and maybe a bit wider. So it is pretty narrow considering the first bevel. Looks good though. I'll probably shave with it tonight (whatever stubble I have left from testing other razors).

It is great news that your razor feels sharper but this is not the double bevel method described on Tim's site. In effect you just changed the angle of the primary bevel to be a little bit steeper and polished it up to shaving sharpness. In Tim's method the second microscopic bevel is only above 10K (The first bevel is established with the 4K and polished with the 8K and Chinese 12K before adding two more layers of tape). Check out his site to see what I mean.

Originally Posted by heavydutysg135

It is great news that your razor feels sharper but this is not the double bevel method described on Tim's site. In effect you just changed the angle of the primary bevel to be a little bit steeper and polished it up to shaving sharpness. In Tim's method the second microscopic bevel is only above 10K (The first bevel is established with the 4K and polished with the 8K and Chinese 12K before adding two more layers of tape). Check out his site to see what I mean.

I do realize that. It is different than Tim's method, but using his, I don't think that this edge would have gotten nearly sharp enough any time soon. I also understand that wedges can take hours to hone, I was just being impatient (after a few hours though) and wanted this blade sharp. It is technically "two bevels" though.

Thinking about it actually, using Tim's described method, isn't it just the same besides the size of the bevel (his method being much smaller since you only use 10k+ for a few strokes) and the polishing of the first bevel? Say I did polish my bevel up to 12k and it still didn't shave, then taped the spine and started at maybe 8k for the second bevel, wouldn't the end result be similar? Technically for either method the second bevel will be the only one actually cutting the hairs right?

On a side note, I test-shaved the razor and it was great! Very comfortable and sharp!

Thinking about it actually, using Tim's described method, isn't it just the same besides the size of the bevel (his method being much smaller since you only use 10k+ for a few strokes) and the polishing of the first bevel? Say I did polish my bevel up to 12k and it still didn't shave, then taped the spine and started at maybe 8k for the second bevel, wouldn't the end result be similar? Technically for either method the second bevel will be the only one actually cutting the hairs right?

No the results would be different. The purpose of Tim's metod is to use just a very small microscopic bevel at a slightly steeper angle at the end of the honing process to completely eliminate the scratch pattern of the lower grits; not to create one steeper bevel to speed up the honing process. It is like changing the recipe for a food dish. The results might still be good but it will not be the same thing.

On a side note, I test-shaved the razor and it was great! Very comfortable and sharp!

That's great news!

I have to disagree fundamentally with the comment about a double bevel not being as long lasting as a single, the raw physics at work dictate that a steeper bevel produces a more resilient edge.

It's like the difference between a Sushi chef's ultra fine Sashimi knife that would probably shave your face as well as any brand new TI, and his Cleaver, which, while intentionally not sharpened to the same degree, has a much more robust grind to withstand the force of chopping through hundreds of pounds of tuna spine without incurring any damage.

Granted this is a dramatization, but there is no way a steeper bevel should deteriorate faster than it's more acute counterpart, if indeed the steels are of identical quality, and the same abuse imparted to them.

There may be an issue with stropping the micro bevel to the same degree as a traditional edge, and thus leaving the edge in worse condition after each shave, but it shouldn't be an issue of the actual process being inferior.

Stropping is a good point. I didn't evaluate long term stropping nor edge resiliance but I was surprised that razors honed like this draw equally on a strop to traditional methods. I've been studying draw phenomenon for a few years and found this interesting.

I've tried this double bevel stuff on about half a dozen razors lately, and I did notice an improvement in the shave-tests. I'm not sure I'll use this technique very often, but I think it is valid.

Josh

Originally Posted by Russel Baldridge

I have to disagree fundamentally with the comment about a double bevel not being as long lasting as a single, the raw physics at work dictate that a steeper bevel produces a more resilient edge.

It's like the difference between a Sushi chef's ultra fine Sashimi knife that would probably shave your face as well as any brand new TI, and his Cleaver, which, while intentionally not sharpened to the same degree, has a much more robust grind to withstand the force of chopping through hundreds of pounds of tuna spine without incurring any damage.

Granted this is a dramatization, but there is no way a steeper bevel should deteriorate faster than it's more acute counterpart, if indeed the steels are of identical quality, and the same abuse imparted to them.

That may not be entirely correct. An acuter bevel might cut with less effort than a steeper one. As a result the material that is being cut could exert more stress on the edge and abrade it sooner. If one would conduct lab test with a given knife and a given material, one could find the ideal cutting bevel that would always be the steepest bevel that could still allow for a fairly strain-less cut, or looked at it from the opposite direction, the acutest bevel that could still offer enough resilience against the cutting forces.

If I'm informed correctly, razor manufacturers have been using bevels of 15 to 17 degrees (someone better double-check this). I think they had enough time (a few ages) to get it right.

I don't know if altering the bevel angle with a degree or so, would be noticeable in the shaving experience. The only one that seems to have done some exhaustive comparison between single and double bevels on the same razors is David (heavydutysg135) and Perhaps Tim Zowada himself.
Actually, the whole hollow grind principle is already a kind of a double bevel thing.
As far as completely removing scratches from lower grit hones, it is my experience that doing enough strokes on my Belgian Blue and there after on the coticule easily takes care of that. I aim for that when I inspect the edge under the microscope between different hones. I understand that Tim Zowada, being a professional knife and razor maker, wants to speed up things a little, aiming for a better production-cost ratio.

Just my random thoughts on this matter,
Bart.

Originally Posted by Bart

As far as completely removing scratches from lower grit hones, it is my experience that doing enough strokes on my Belgian Blue and there after on the coticule easily takes care of that. I aim for that when I inspect the edge under the microscope between different hones. I understand that Tim Zowada, being a professional knife and razor maker, wants to speed up things a little, aiming for a better production-cost ratio.

Just my random thoughts on this matter,
Bart.

I agree with these comments.

Originally Posted by Bart

That may not be entirely correct. An acuter bevel might cut with less effort than a steeper one. As a result the material that is being cut could exert more stress on the edge and abrade it sooner. If one would conduct lab test with a given knife and a given material, one could find the ideal cutting bevel that would always be the steepest bevel that could still allow for a fairly strain-less cut, or looked at it from the opposite direction, the acutest bevel that could still offer enough resilience against the cutting forces.

This comparison deals with cutting in a line parallel to the edge, not perpendicular. I agree when severing a given fiber there is always a "field of stress" that develops as the edge forces it's way through the media. And the the field of stress increases with bevel angle, so the lower the angle the easier it is to cut with that utensil.

But ease of use and edge retention are not the same quality. And the two different cutting motions do not "necessarily" correlate.

This is one of those situations where we are dealing with such a fine edge that a slight increase in angle should not affect the ease of use as much as it ought to increase the edge retention.

Here's a quote about a BIC razor blade taken off a triple bladed cartridge that was inspected under a micrscope:
"The third microbevel is only 0.0009" wide and shows no scratches. It was probably done using an abrasive with grit under 1 micron. In my testing of honing compounds used on leather strops, I have not found any that produces this fine a finish. This leads me to suspect that BIC is using a very fine abrasive paper to finish their edges, or possibly using a sub-micron diamond honing compound. ...Images of a more recent blade, taken from a three blade razor, suggest that the final include(d) angle is actually over 35 degrees."

I think BIC has done their research, and apparently they've found it acceptable to have a dramatic increase in angle if its small enough and polished well. Though I seem to remember seeing a "How it's Made" episode where they attributed the improved edge retention of the micro bevel to laser cutting. but not sure on that one.

EDIT: This is just a frame of reference for the validity of double bevels and edge retention, as that is probably the primary goal of BIC's design, not comfort. It's possible and plausible that 35deg. is too much and would probably suffer in terms of comfort compared to traditional razors, but the point is that the double bevel aids (at least a little) in edge retention.