Challenges to date :
| Challenge | Winner | Total |
|---|---|---|
| Sharpening CPM-10V Phil Wilson 62.5 HRC | C Ashmore | 3 |
| Sharpening Richmond Artifex | Astrowhale | 1 |
| Busse Combat Battle Mistress | xCaffieneJunkyx | 2 |
| Spyderco Catcherman | Paradextactical | 1 |
| Spyderco Air | C Ashmore | 3 |
| 12qwaszx35 | 1 | |
| Laminated japanese kitchen knife | nihontoman | 1 |
| Chumgeyser | 3 | |
| Benchmade 710-Axis CPM M4 HSS | whatfor5 | 1 | Chumgeyser | 3 |
| C Ashmore | 3 | |
| Cold Steel AK-47 AUS-8 stainless steel | shurdi3 | 1 |
| ZT0561, Piranta Edge, Lum Chinese, small Sebenza, Rajah III | Braynstorme | 1 | xCaffieneJunkyx | 2 |
| Cold Steel Rajah III | Chumgeyser | 3 |
| Miyabi 7000 D Chutoh | jumblejumbo | 3 | Warescrackdown | 3 |
| Bark River Grasso Bolo Fail | James Elam | 1 |
The challenges in detail are as follows.
Intro :
The challenge is to determine how come the edge was reset (apexed) much faster on what is in general a much slower cutting stone?
The solution is that the combination of very low angle and soft abrasive which could not cut the carbide cause the carbides to be torn out of the edge with the stone which in general is slower.
There are a few interesting general results of this :
Intro :
The solution is that one side of the edge was originally ground at a much higher angle and that side of the knife isn't being apexed at all during the sharpening. This is a common issue in modern knives because of the common methods of power sharpening often produce such bevels. This can be a non-trivial issue for the high carbide steels because the grindability is so low that even a very small in width heavier heavy bevel on one side (which can not be seen) will prevent that side from reaching the actual apex without significant regrinding.
This is why if the edge does not forming clean this should be one of the first things to check. Destress the edge and see if it re-apex from both sides equally as rapidly. If one side does not respond then just work that side only until it apexes.
Intro :
The solution is deceptively simple - the two cuts were done on different spots on the edge. This problem, while sounding silly, is actually very critical on many knife retention videos as often cutting is done with one area of the edge but then the sharpness checked on a different spot - then of course follows praise for high edge retention.
The reason that only part of the edge was sharp in this case was that a section of the edge was recurved (not intentionally) and this was keeping that section of the edge off of the stone. This is a quick check when destressing to ensure that the entire edge develops a uniform flat.
Intro :
The solution was that coarse shaping scratches are left on the bevel.
This not only causes the problem noted but it is the reason that people often conclude that high carbide steels have slicing ability due to the carbides themselves cutting. The low grindability of those steels means that those coarse initial scratches are staying on the bevel due to taking much longer to abrade and while the knife does look polished those initial scratches are still on the edge giving it a coarse finish.
Intro :
Describe in a YT comment box how to conduct an experiment which shows the difference in performance between the edge retention due to the influence of two different people sharpening this knife on a cheap benchstone.
There were a number of excellent responses, the top answers utilized :
This challenge of course shows that with a little thought it is possible to do very meaningful comparisons with just very basic equipment through use of known scientific methods.
Intro :
Your friend drops off the knife and notes the middle of the blade never gets sharp like the rest of it and this is consistent each time he sharpens it. He uses an inexpensive benchstone which has a fine/coarse side.
The reason for this problem was that the stone was unevenly wore in the middle due to reshaping of the tip and it created a hollow which prevented the stone from sharpening the blade in the middle. This is a common problem with soft stones which are not frequently lapped and/or tip work is done first.
Intro :
Your friend drops off a 710, he wants you to regrind and sharpen it to maximize the ability of the steel. In one comment box :
The point of this challenge was that the grind of a knife and how it is sharpened has to be optimized by taking into account the following :
One of the top answers :
So CPM M4 has relatively high? wear resistance at relatively high strength/toughness which is why it finds itself on CCs. Take down the saber grind to a? flat grind, which won't significantly weaken the knife, but will improve cutting. Presumably the stock geometry is thicker behind the edge bevel than it needs to be. Even a relative novice should be able to safely use CPM M3 at ~.5mm behind the apex bevel. 20 inclusive with micro at ~35 for apex. Remove initial grinding HT damage.
Intro :
The solution to this is that the angle of the stone across the stone sets the aggression and by changing the angle of the knife across the stone can make it more aggressive when you draw cut towards or away from you.
Intro :
From the following :
Using one YT comment box for each, argue that :
One of the top selected answers :
xCaffieneJunkyx I would argue that the 0560 is the most inconsistent. We see that it has varying degrees of comfort in the handle. Across the board however I think most would? agree that during use that extends for much duration it is going to be uncomfortable. It has inconsistent lockup. It has inconsistent initial sharpness out of the box. And may even suffer from burnt edges. Also (presuming without calipers) decent variety in edge thickness ect. Seems to have a initial wide margin in edge retention as well
The point here is that design consistency is very critical in knives and that it makes no sense to have conflicting aspects.
Intro :
The point of this challenge is to explore commentary in detail, to subject reviews to critical evaluation and feedback. This both provides more information to the listener/reader but if the reviewer is open to it then it allows them to learn as well.
Intro :
The solution was contamination of the water which was being used on the stone. Very fine waterstones have to be kept very clean or else the grit of the stone can be masked by simple dirt which can easily be larger than the micron size particle rating of the stone.
Intro :
This knife suffered catastrophic damage in what would normally be considered very light use ref. The performance of the blade was defended from the maker with the following
First - No matter what - the knife is still fully covered under warranty.Lets step back and look at the situation.
Whenever You have a Half Moon section out of a blade - Any Blade - Any Maker - it is usually not the blade - Not the heat treat or even the kind of Wood You are chopping.
It is what we all call the Unsupported Chopping Phenomenon. This is where the knife bites and either the user or the Wood Being Chopped turns laterally and literally takes a Half Moon out of the blade edge.
We have seen this happen with a large number of Blades by a large number of makers and none of them were heat treat or even edge thickness related.
That half Moon Breakout is always indicative of this happening.
The Grasso Bolos are 5160 and all of them were Heat Treated the same way - in fact they are all heat treated together at One Time.
If there is a Heat Treat Problem - they either all have it or none of them have it. Since we have had a ton of Folks that have tested them I would say we can rule out a Heat Treat Problem.
To Add - Since these are all Hand Ground - They all spark the same way in grinding and if one of them were bad - the person who Ground it would instantly notice a difference in the Spark Trial and point it out. These are all Ground by people - not robots - so any variation in the Way a blade grinds would be caught right away.
More specifically - That knot section was the first Thing Chopped and if You watch Carefully the chopping was - indeed - Wobbly -Causing more lateral stress than the later chopping with any of the knives.
When the Second chopping was done with the GB-II was done - it actually Cut Deeper and Faster than any of the other knives and was not damaged Further. If it was the heat treat - it would have failed and been Damaged Further. - It was not.
Had the Op Chopped with the GB-II further down on the Wood - this most likely never would have happened. You will also notice that as the Chopping Continued the OP became more Comfortable with Chopping and all of his Strokes were more Deliberate as he gained more confidence in what he was doing.
You will also notice the Spark that was Generated on that last set of chopping. Wood Does not make Steel spark. Commercial Lumber can and does have little pieces of Saw Blade in it - Hence the spark. That was NOT what caused the Break out and it did not damage the Blade on that last set of chopping - It usually does not on any knife because the sliver of Saw Blade is too small to damage a blade.
If we actually did Slow Down the Video Frame by Frame would could identify and isolate the instant that the Half Moon broke out of the Blade. I am Confident that the instant where that happened was a Combination of the Wood Moving and the OP's hand giving a lateral wobble. This would have been a 90 degree movement of the Wood combined with a 90 degree wobble in the opposite direction for the split second.
The Initial Chop - on the End of the plank was causing the rest of the plank to lift slightly off the Ground - not where it was being impacted - it was actually causing the rest of the plank to lift into the Direction of the Chop at 90 degrees to the Blade.
The harder knot only made the plank lift or move more - it was not the actual cause of the break out.
A few weeks ago Ethan Becker held a Becker Head Outing in Tennessee and this same Phenomenon Happened on a number of knives from a number of makers - Some were even Custom Knives (Not a Bark River that time).
Jim Nowka was in attendance and when he called me that Monday he started to tell me about it and I stopped him and Finished the Explanation of what he was about to tell me. He was shocked that I knew exactly what had happened on all the Damaged knives - just from his description over the Phone.
That Half Moon Break out is not uncommon and can happen onAny Brand of Knife and actually can be duplicated.
All of You might find it interesting that All - I mean ALL - Bark River Knives are impact tested - by the exact person that Grinds the blade - Right on the line - At the Station that the Blade was Hand Ground by slamming it into a section of very old - very dry 4" X 4" post to check the Terminal Geometry on EVERY knife.
The Bottom Line is that it truly is a Combination of User Error and Lack of Support of the thing being Chopped. It is totally unintentional and not something to point fingers at or about - it just sometime happens.
This is what solid Company Warranties are for.
No matter how it happened it is 100% covered under our Warranty.
I hope I have gone over this in enough detail to make it Clear.
Send the knife in and we will re-grind the blade at no charge.
The challenge was to defeat that argument which is riddled with nonsensical physics and inconsistent logic.
Comments can be emailed to Please Use the Forum or by posting to the following thread :
and/or the YouTube Playlist.
| Last updated : | |
| Originally written: | 14/08/2013 |