A Question About Chop-off's

psychicevolution

psychicevolution

Joined
Apr 11, 2009
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I've been doing some reading of older posts specifically about the Trail Master VS the CGFBM in a chop-off. Now, I am no expert, but isn't it unfair to try to show the comparison of two different blades in a chop-off without first establishing that they both have the same level of sharpness? I mean in the YouTube video of the TM vs the CGFBM you have to assume that the reviewer has both blades equally sharpened. But what if the TM was freshly honed and the CGFBM had a dull factory edge without ever being sharpened? That wouldn't be a fair comparison would it? Shouldn't it be explained / shown that both blades have the same level of sharpness before the chop-off began to be a valid review? Just curious....
 
If you are talking about professional and scientific reviews then its one thing. When you look at videos on youtube or done by friendly forumm8, then you should take them for what they are, a nice gesture on behalf of someone who gets nothing from it and shows off the knife.

There are many factors to consider besides the one's mentioned in a review, and a big plus of those reviews is the fact that you are able to tell the dimensions better then with pictures.
 
A scientific chop off would be hard. 20 test subjects of each knife model, factory edges, same density material being chopped through at the same angle and no human involvement in the actual chopping, just a robotic arm doing so with an equal amount of force each time.

Me? I just like watching them.
 
I never asked for anything "professional" or "scientific", just a simple demonstration of sharpness would do. I believe it is too easy to give your favored blade that "edge" in a chop-off by giving it a razor sharp edge without doing the same to the other blade is all. Personally, unless I know the person doing the chop-off to some degree, I cannot "take them for what they are". Yes, I do like watching the reviews regardless, but they don't really mean much to me. I really like Ankerson's videos and chop-off's but I know that he is a cool guy and honest with his reviews. I cannot say the same for others, especially those who would chose a Trail Master over a CGFBM for chopping power.

I am not trying to put down chop-off videos. I just think it would be a proper thing to demonstrate the sharpness of both before the chop-off is all. Is there anything wrong with wanting that?
 
Sometimes the point of those comparisons is to show how each knife performs with it's factory edge.

One thing that Cliff Stamp concluded after doing many, many reviews/comparisons was that one of the biggest factors in performance was not the sharpness or the steel, but simply the edge geometry. He distilled it down to a rule: Geometry Cuts. After that he tried to bring all edges to the same geometry (and sharpness) before any comparisons.
 
The thing with "sharpness" is that it is a fickle aspect in assessing how a knife performs... too sharp is just as much a problem as too blunt because with a very fine edge on most steels hardened in the 58 Rc zone the edge can "roll" when used on wood or cardboard quite quickly. Once the edge rolls it becomes less effective than a blunter edge .... so performance is compromised quickly.

A good example of this is seen with scandi bushcrafter knives .... usually the scandi grind is around 15 degrees per side or less ... sometimes it is 10 degrees per side .... sharpen them with the flat of the edge on the stone and you can see the edge is so thin it is tearing and never really getting sharp. You then need to apply a secondary edge either by use of the stone or by stropping. Most of my Scani knives perform best with a secondary edge created by a mixture of honing with a ceramic and stropping on leather with green rouge.

Infi works just the same .... too thin an edge and it will roll before it gets blunted from use ....

RG's comments about geometry and Cliff Stamp's findings are interesting .... Jimmy Fikes is also of the same view that geometry counts for a great deal and he is very famous for the cutting edges provided on his custom knives. We see it every day in the kitchen .... a thin ground cheap kitchen knife will still slice a tomato despite a butter knife edge because it is thin enough to do the task. Therefore on many knives they can perform better on tests like slicing and cutting if they have a thinner profile behind the edge.

For me I tend to find that the longest lasting edges on cutting tasks come from a mixture of profile and Rc hardness and edge geometry in terms of getting the right balance to the edge so that it is sharp but will not "roll". A harder Rc knife enables a thinner profile to be used but there seems to be a limit on all steels .... as all steels will roll ....

I find it interesting when people post that they prefer a 15 degree or less edge on their knives. My experience of using edges that are very thin is that you lose the edge from rolling before you blunt the edge .... those sort of edges need to be worked like a Barber uses his razor .... they need to be frequently stropped to keep the edge central.

Compare that to how a competition cutting knife is sharpened. They are taken very thin on a flat grind and a secondary convex bevel is applied at a steeper angle. This stops the rolling but the geometry of the knife has little resistance behind the edge area .... this is like combining the benefits of a kitchen knife with a very sharp edge on a steel which is hardened sufficiently for the "blunting" to take a long while.

I can guarantee most people on here probably have edges "rolling" before they are "blunting" ... I know I do .... it is a hard thing to get "right" because it takes a lot of work to re-profile an edge/knife so the above ideal set up is found. Infi blades come "thick" because of the possible need to cope with chopping stuff which professional knife users don't chop. Breeze blocks and metal etc come to mind.

I have though thinned down some knives and done edges like those on competition blades and they are a joy to use .... I did this to a SJTAC and a Skinny Ash .... I also fine the blade profile on a S5LE to be pretty good right out of the box .... and so is a Basic 5 .... perhaps the Basic 5 is a different example because it has a very unique ASM grind .... but on my large chopping blades I go with a simple convex edge or on some a zero convex edge. These type of edges and "use" they encounter "must" resist "rolling" otherwise you need to strop the knife during "use" to keep the apex right.

My point being that in an afternoon's chopping test where "stropping" was counted as a negative .... my edge preference to ensure my blade would last the course and do well .... would like as not be well off the pace on shaving arm hairs before the work began. It would however be able to carve wood at the end of the test and do cuts which knives where their edges had rolled would really struggle. Some knives can almost do it all though. My KZ can take three different edges .... one near the handle for carving .... one on the belly for chopping ... and a different one near the tip for reaming and point work. A NMFBM is long enough to also be sharpened that way and is perhaps easier to use. Doing edges like this though takes a long time to get right .... the movement of your hands on the passes on a belt sander need a lot of practise and consistency. For this reason once I get the blade close .... I prefer to use a "strop" to finish the edges off.

Anyway .... sorry for the long post .... but what the OP said is very "true" that knives need to be prepared as best they can to do a "truthful" post .... but at the same time what amounts to the best preperation can often not show itself by a simple "hair popping" sharpness test.
 
We need to teach more people about the utility of the microbevel. Cliff Stamp promoted it, and lately Vivi has taken up the cause of advocating thin bevels with a slightly steeper microbevel to protect it.

I like your three edge idea, Peter. :thumbup:
 
Peter, I learned a TON from your post and you answered my question and much more. Thanks so much for taking the time to post your reply. Very cool! :thumbup::thumbup::thumbup:
 
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