TikTock said:
...what sets the MS-level guys apart from us new makers.
Opinels would likely not pass MS finish levels, those were the class of blades being discussed.
STR said:
Yeah I'm pretty sure he is talking about 'larger fixed blades' with those drawing examples.
No, in the parpagraph right before it there is no mention that this is something constrained to large fixed blades, it is presented as a general principle and is misleading simply because it compares a thin convex bevel to a thick v-ground edge and uses this to promote the idea that convex bevels in general cut better. What you have in effect fundamentally in the picture is the effect of a relief grind and you can do that with a flat bevel as noted by J.J. among others.
It sounds like you are confusing edges and grinds somewhat also Cliff.
No, the article covers both, and the same principles apply. You can sharpen a full convex blade on a straight stone for example, or a Sharpmaker and maintain the geometry. Or just use it to add a v-bevel as Fowler does and companies like Fallkniven who both run full convex blades.
A Mike Stewart Bark River knife for example is a true convex grind from the beginning to end. It isn't a hollow grind that has later been honed to reshape the primary bevel to a convex edge. It also isn't a convexed with flat sides which is no longer a 'true convex' when that is the case is it? I would call that a 'modified convex' or a 'modified flat grind' personally because it incorportates aspects of two different grinds.
There would be no way to tell if a convex grind was ever a flat grind, all bar stock is of course flat ground to start with anyway. As for the process, I have fully convex flat stock, I watched a friend of mine do a full convex grind with a file, Alvin has done it with a angle grinder (initial shaping he does finish it beyond that). Ask him which is easier, the full convex or a full hollow. I have examples of both from him and yes he describes both of them as fairly easy once you know the method, he encourages anyone to do it and even gives away prehardened blanks on a regular basis.
By the way it is generally believed that it does take skill to convex grind a blade or tool from scratch.
It takes skill to do anything, however the arguement was that it takes more skill, so much so it prevents it from being used. Is Dozier actually unable to do a convex grind, is Wilson, are those guys really showing a lack of skill by not using convex grinds?
TikTock said:
Convex allows you to create a more efficient geometry without overly thinning the stock.
So if you took a convex ground blade like an Opinel and then flat or hollow ground it, it would then uniformly cut worse? This isn't the case obviously - in general. As a trivial example, I can take a thick convex bit on an axe and rip off all the material and make it flat and it will cut much better. I can then hollow out the primary above the bit and it will cut better still. Several people have done this on axe heads and noted the results, it is really dramatic when the initial convex profile was very curved because it is a matter of cross section. Now the same general principles apply obviously to thinner blades. This however as noted doesn't mean they don't have any use, however the advantages are not as general and all inclusive as noted making the one grind directly superior.
TikTock said:
Again, I think you are way off here. Are you taking about convex edges or convex blades?
I have both, custom and production with varying bevels, some even run dual distinct convex grinds of different curvatures and others combine them with deep fullers, multiple even.
For a chopping blade, for example, if chopping ability was driven off the thinness of the blade, we'd all be chopping with razors.
For a chopping blade you need weight to give power and you need thickness to reduce binding, the latter is why soft and hardwood axes have dramatically different profiles. The durability limit on cross section is *way* below what is needed to prevent binding usually even on really cheap machetes. You can thin them to the point they have to be chopped out of woods and the edge will be stable. Convex grinds do have advantages in wedging, but full convex grinds are actually only used on soft wood cutting tools, hardwood felling axes actually have primary hollow grinds with a primary convex edge and a secondary v-ground flat bevel for durability. Some axes, the racing ones have more complicated geometries depending on the wood type and user preference, one of them are simple convex.
-Cliff
Thats why I find the statement by Cliff amusing at best I guess. It isn't as easy as it may look and one or two knives under your belt isn't enough to allow you a good enough perspective to make a bold statement like that that it is not all that hard or complex or that it doesn't require a higher level of skill to pull it off. IMO.