Resharpening...Shaving Or Not?

[Eric Isaacson]

Lately, I have been doing a lot of work in my yard and around the farm with my BA-E. I've noticed that with the particular materials that I'm cutting a more aggressive edge works very well. When resharpening the knife I stop a little short of Shaving Sharp(it will slice paper but not shave), this type of edge seems to really grasp the vegetation and branches(any softer materials) and make cutting easier. I have also noticed that when chopping on small branches the more aggressive edge doesn't slide on the branch, of course this also has to do with the angle of attack but I'm sure the more aggressive edge helps.
Now if I were cutting harder materials I'm sure that the shaving edge would cut better.

I'm assuming that the micro-serrations are larger on the more aggressive edge, therefore it works better on the softer materials. The Shaving sharp edge would have smaller micro-serrations and work better on harder materials. Of course this all could be that I'm just too lazy to put that final touch on the blade to get it to shave.
So what do you do when resharpening? Do you take the edge back to shaving sharp or do you stop a little short? Has anyone else come to the same type of conclusions or am I just possibly grasping at straws.

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Eric Isaacson

 

[Climber]

Eric - i've been doing lots of cutting in yard-work this week, too; also cleared trails at Wilderness Park with vshagios & Lukers from the forums.
i've pondered those questions myself...
i've concluded that if i leave my edges at as low as a 325 grit, the edges "bite" into vegetation (or cardboard, for that matter) so well, that it isn't necessary to further refine them. As U say, for harder materials a finer edge does better, but for soft "live" stuff, like branches, the aggressive & rough edge does real well.
A case in point: (i know this isn't a D. Boye forum, but Jerry won't mind!) my Boye Basic #3 (4" Blade) cuts BEST with that low grit, straight off of my DMT coarse diamond stone (325 grit); if i get it shaving sharp, or smoother on the edge, it only cuts arm/leg hair well! The chromium carbides, they tell me, are optimized for cutting if left "jagged" - microscopically speaking, of course (coarse?

)
So "sharp IS what sharp does...!" If hair-cutting impresses friends, & they're only collector knifeblades, take the time. Or if cutting hard materials is necessary, refine that edge; But if cutting/slicing soft materials is what's needed, save your sharpening energy for the work-task.
i've noticed that the edge LASTS LONGER at that grit, than at a more highly polished edge, through actual use. The finer edge blunts easier/quicker than the "micro-jag~".
Happy Knife Work to ya!

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Clif
"Percival... I never knew how empty was my soul until it was filled."
Arthur the King upon sipping from the Grail.

 

[Cliff Stamp]

Joe Talmadge discusses this in detail in the FAQs and as well it has been brought up before on the forums. One clarification is necessary, shaving is a matter of alignment. You can shave with even really coarse edges if they are ground well, I have seen it with an x-coarse DMT hone as well as a 220 grit SiC Japanese waterstone.

If your coarse edges are not shaving it is probably because the edge is burred slightly to one side, not to the full depth of the microserrations. Some possible causes can be a loaded hone, or too heavy a stroke, or a hone not aggressive enough for the steel in the blade.

A burred edge will cut at a distinctly lower level than a well formed one and last for a much reduced length of time. There is no need not to have a blade shaving sharp. As for the level of polish, well that depends on what you plan on doing as you noted. For slicing, generally you want teeth that are large enough to sink in fully, larger teeth require more force to be exerted down on the blade and may not be optimal, and smaller ones more strokes because the teeth cut a shallow track.

-Cliff

 

[Eric Isaacson]

Thanks Cliff,
If I'm not getting it shaving sharp but I'm able to push cut paper, does it sound like it is burring slightly? I thought this could be the case but I'm not seeing any decrease in the level of performance or reduced edge life. However, the materials I'm cutting are soft.
Thanks

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Eric Isaacson

[This message has been edited by eaisaacs (edited 06-14-2001).]

 

[Cliff Stamp]

Eric :

<font face="Verdana, Arial" size="2">I'm not getting it shaving sharp but I'm able to push cut paper</font>

That is pretty interesting, I have never seen that scope of performance before. A push cut through paper is a very highly aligned and well formed edge. That is a level of sharpness *well* above what is necessary in order for the blade to have the ability to slice paper. I have seen lots of blades that can shave but still not push cut paper, but never the other way around.

Of course shaving is a pretty vague term. In the strictest defination it is the ability to push cut through even slight hair without any scraping. If the hair is stiffer then it is far easier to shave with as it provides more resistance to being bent and thus will allow a higher level of pressure on the edge of the blade. I can easily freeshave my beard for example when I finish sharpening the Battle Mistress, using a push cut well above the skin like trimming a hedge.

Most of the coarser edges I have seen that shaved did require a bit of a slicing motion, but the force applied would be light, they would not need that much force so as to aggravate the skin. I usually put a decent level of polish on the Battle Mistress because it is used for high impact work on hard woods and coarser edges will deform more readily. However the finish is not a complete polish as that would retain little slicing ability. I finish on 1000 grit SiC sandpaper on Mylar backing, and a few passes on a canvas strop loaded with a wax/chauk paste.

Back to your blade, regardless of it is shaving or not. If the blade is performing well at what you want it to do, that is all that really matters. Sharpness tests are only relevant if they correlate well to actual use, in this case it seems that shaving does not for you.

-Cliff

 

[Eric Isaacson]

Thanks Cliff,
I thought of a couple things while reading your last post.
1)Maybe I just have Tough Hair

2)I agree the edge seems to be working for me, which case I will probably leave it.
3)I may need to try the push cuts again to check the validity of my work.




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Eric Isaacson