Trying to learn and steel need some help: Blade Angle Geometry

A few observations with the vid & opinion expressed therein:

1. The branches he was chopping were mainly rotten and breaking rather than chipping out like green wood. To his credit he addresses the condition of the wood, not that it would have escaped unnoticed otherwise :rolleyes:.
Offhand, I'd estimate 65% of what I observed, the logs were breaking or splitting primarily from inertia and stock rottenness. You can see this when the blade sinks into the log and a "break" occurs further toward the unsupported end of the log right <on your comp. screen> of the impact. Some of the logs even bust and split out lengthwise from the underside before the edge penetrates to that depth. Anyone could have taken 1/4 inch raw bar stock and done as clean a job on some of the "cuts." So, I'm a little perplexed why he'd choose this particular condition of brittle wood to demonstrate bite and choppability. This wood would have been more conducive to a karate exhibition rather than a knife chopping vid.

2. I noticed when he does encounter some wood with reasonable integrity like ca. 3:12, his chopping technique degrades starting about 3:21 to compensate for the tougher chopping he encounters. I have waved edges in machetes and non-Bussekin choppers with that type of technique*. With those blades under those conditions I've got to be mindful to work the blade out of the cut with vertical up/down levering rather than twisting it horizontally out of the cut.

*NOTE on technique...I define that type of chopping technique as bad or degraded in relation to the tool being used, not the technique itself, necessarily. That is, twisting the blade out of the cut is an effective way to hog out large chunks of wood and get the wood processed quickly-- but only if your tool is up to the task. For instance, I have NO PROBLEM twisting my BM's, Basics, or Squatch out of cuts because I have found they can take it. I've got a SR R9 that I have no problem twisting also. But I largely avoid employing that twisting technique with other blades, custom or otherwise. So, I'm not surprised he noted some edge damage, pin knots not withstanding.

3. In the commentary he states a more rearward grip moves the sweet cutting spot of the blade more rearward. But he basically maintains the same grip area on the handle throughout the vid. He varies the impact point on the blade a bit, but the grip is not varied much at all. Puzzling why he'd make a major point about varied grip and their respective blade impact sweet zones yet not illustrate it in his lengthy chopping vid inset. I'd liked to see some more of the versatility he claimed the blade design + edge geometry possesses. A little batoning demo. would have also been welcomed. But this may have been stylistic choices on his behalf.

Minor quibbles perhaps, yet they stand for me.
 
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Actually, just putting more thought into this and I actually was not saying what I had really had intended in my original posts here. What actually should be noted is that in addition to lowering the edge angle as the OP described, you will also want to thin out the primary grind behind that edge bevel as the the thickness behind the edge increases by lowering the edge angle because the edge bevel now terminates farther up towards the spine on the primary grind.

Due to the thick cross section behind the edge bevel that now exists once the DPS have been lowered, regrinding the primary in addition will add considerable performance over just lowering the DPS of the edge bevel… in addition to more expedient resharpening after dulling as you have to grind away less metal to re-apex the knife. At a certain point of reducing the thickness behind the edge, you MUST ALSO reduce the edge bevel below 10 DPS to ensure that the edge bevel will contain the failure rather than pushing it into the primary grind.

Regarding the video Petey, you might wish to pose those questions to Cliff on his forum as I can't speak for him and I know he would be happy to speak more at length for you on that subject regarding his experience/views on that matter… http://www.cliffstamp.com/knives/forum/list.php?24
 
Back to the original post, look to the design of the knife and philosophy of use prior to grinding in any new bevel. In my experience, Infi and Sr101 favor toughness over edge stability. Furthermore, pursuing a very thin edge may have cosmetic consequences as you remove steel further up the face of the blade and have a very wide bevel compared to knives ground thin from the outset. I advise a conservative approach that does not favor excess removal of metal. It cannot be put back on. Try out an edge and see how it performs. Use it. Evaluate. Adjust. An edge should evolve over time based on the design and purpose of the blade paired with the characteristics of the user.
 
I agree with petey, the video unfortunately does not show what happens to a thin edge on hard wood and knots. I do think that if you grind an edge down to 10 dps, you will see a lot more damage than if you have it at 14-15. What cliff is talking about is a little confusing. Having said all that I would love to see the theory cliff proposes drawn out on paper as compared to a normal profile. Because it honestly does not make sense to me. I may do so on his forum
 
Panthera tigris said:
Back to the original post, look to the design of the knife and philosophy of use prior to grinding in any new bevel. In my experience, Infi and Sr101 favor toughness over edge stability. Furthermore, pursuing a very thin edge may have cosmetic consequences as you remove steel further up the face of the blade and have a very wide bevel compared to knives ground thin from the outset. I advise a conservative approach that does not favor excess removal of metal. It cannot be put back on. Try out an edge and see how it performs. Use it. Evaluate. Adjust. An edge should evolve over time based on the design and purpose of the blade paired with the characteristics of the user.
Click to expand...

Bolded part: That is right on the money. Every knife is different and you cannot apply the same criteria across the board. A 2 inch wide flat ground blade will have a much thinner profile than a 2 inch wide sabre ground blade of the same thickness. There is a lot less metal down near the edge on the flat ground blade. Much better slicer. The edge you put on this blade imo will be larger than the edge you would put on the sabre ground blade. Which is what cliff did with the blade in that video. That blade is a sabre grind and not wide. He went thinner on the edge because he had more metal behind it and had to go thinner to make up for the obtuse blade profile. at least that is how it looks to me.
 
Thanks for all these responses!!! It looks like I will have some work to do sharpening soon!!! I anxious to see what type of an edge the Elmax take along with some of the larger blades. Thx again for everyones input.
 
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