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Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly

Posted by jasonstone20 
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Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 01, 2020 08:43AM
This happens to me every once in a while. I get an edge that feels sharp but doesn't cut well. The blade will cut well after a full sharpening, but not after touch-ups or stropping. I am not sure what is going on when this happens. I could feel some micro-chips in the blade, and I should have looked at the blade under magnification before sharpening but I didn't. Has anyone else experienced this? The blade had sat unused for a many months if not a year.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 01, 2020 02:58PM
Just for the sake of conversation,recognizing you are better read on this sort of thing, could there be some sort of work-hardening going on with the apex?
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 01, 2020 03:08PM
tarantella,
I am not sure. The edge was behaving as if the steel is fatigued, as I can't bring the edge back with stropping or touch-up sharpening.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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cKc
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 02, 2020 05:50PM
Whats the blade steel? the composition of the steel as well as the HT is going to play a huge part in what may be going on.

lots of theory could be offered, but without details and inspection they are just that.

you do a proper sharpen, and its sharp? is the sharpness holding long, or dulling quick, and then failing to strop/touchup?

you said there are some chips.. assuming you didn't cut things that you'd expect to chip the blade..
high carbide steel could be carbide tearout, rather than chipping.
could be the matrix steel is too soft allowing the carbides to tear out.
could be too brittle steel allowing it to get crisp and sharp like obsidian can, but then its fracturing.. still might feel sharp because jagged, but not in the right way to cut as the apex too wide and uneven (light reflections?) resists touch ups because the steel too damaged now.

other alternative.. too soft..
sharpens up well.. but then in use you get a complete rolling over of the edge like a burr thats folded over onto itsself.. some bits so soft might catch on cutting materal and rip out.. but the rest is now curled over and cant be touched up..


there are just too many ways a knife can be sharp with a good sharpen and then fail in the way you are describing.

not sure why it sitting unused plays any part in the issue? except unless it was not really in the condition you assumed it was when you put it down

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 02, 2020 07:25PM
Kyley,
It's an old Benchmade AFCK in ATS-34.

Before I just sharpened it the other day, I had put a new edge on it with a full Japanese waterstone sharpening. I could have just put it away with a good amount of use and forgot about it, thinking I would sharpen it before I carried it again.

I laid the edge back pretty far, close to 10°-12.5° per side, so the edge apex could have a lot of carbide tearout, and that could be the whole issue.

I haven't had great luck with Benchmade's ATS-34 and 154CM heat treatment being very consistent. Sometimes the blades HT is good, and the blade sharpens nicely, sometimes not.

I don't remember having an issue last time I used the knife, I think I was happy with it. I was doing a thread about it on this forum, I have to find it and see what I was doing.

As far as the knife being not used for sometime, I have noticed a small decay in high sharpness, most likely from corrosion and metal set/memory with knives that have not been used for more that a week or so, stainless steel or not. That is most likely why I didn't sharpen it before I put it away.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 02, 2020 07:40PM
This is about one of the other AFCK knives I have, the 806 Axis Lock in D2. I think I carried the 800 ATS-34 right after or during when I was using this one:
[www.cliffstamp.com]
or it could have been around this time:
[www.cliffstamp.com]

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Edited 1 time(s). Last edit at 04/02/2020 07:50PM by jasonstone20.
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 03, 2020 06:35PM
I forgot to add that my expectations of sharpness and cutting ability are fairly high. The edge that was not cutting well would pass all of the normal cutting tests. What was happening during cutting was it took more force than normal to cut the double corrugated cardboard, and sometime the cut would just rip the cardboard. This is in a mostly push cut. Also, there was a burr left over on the serrated part of the blade from a quick and dirty sharpening job of the plain part of the blade. It felt like the blade was too thick behind the edge or it had a high edge angle.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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cKc
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 04, 2020 07:40AM
Interestingly 154cm and ATS34 are 2 steels that were really in fad in the early 2000's + but there was wide ranging complaints in regards to very flexible quality control in heat treatments. at the time I dont think i ever had a knife of either steel that i didn't just hate from a sharpening perspective.. would take 440c over either of them.. (i would say because people just did better ht)

what you are describing is every leatherman 154cm blade i've ever used
grinning smiley

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 04, 2020 03:01PM
cKc,
Yeah, Benchmade's HT can be hit or miss I have noticed. Not enough to were the knife is unusable, but enough for me to think it needs to be sharpened more that it should. ATS 34/ 154CM isn't bad if it is has a good HT, the last Benchmade I got in 154CM (Mini-Griptillian Sheepsfoot) had a great HT. I am thinking that S30V is a better steel for knives than ATS-34/154CM, but I have noticed the same issue with Benchmades HT of S30V, it is either good or not to good. Kershaw has the same issue, they both use the same heat treatment facility here in Portland, OR. My friend used to work there, and I don't think they use the best practices for cutlery heat treating.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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cKc
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 04, 2020 05:52PM
I've only had one Benchmade 940 that was a user.. its edge was complete crap from the factory.. i zero ground it and took about 1/4 mm off the edge and for the last 10 years been nothing but excellent.. who knows if its the edge or the reprofiling.. i think often the HT is ok, but the sharpening is dry, and done on a grinding wheel which is the worst

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
cKc
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 04, 2020 06:03PM
just went back to look at a factory tour.. sharpened on a high speed 10" belt wheel in the video..

so yeah.. sure its going to get piping sharp and do a paper test in the factory.. they only testing 1 or 2 cuts, not testing the edge is not burned

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 05, 2020 12:56AM
cKc,
Yeah, their edges are burnt. The Mini-Grip I got a year or two ago actually had a great edge on it, like the Benchmade sharpening jobs of old, but it was still burnt and only lasted a week of light use before it needed to be resharpened. I have a 940 in S30V that I zero ground by hand and put a 10° per side micro-bevel on it, and it is one of my favorite knives, the 940 in general being one of my favorite Benchmades. It's weird how the S30V doesn't micro-chip at 10° per side while 154CM, D2, and VG-10 will.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Edited 1 time(s). Last edit at 04/05/2020 02:48PM by jasonstone20.
cKc
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 05, 2020 10:14AM
This reminds me of an issue i had with a batch of my micro hikers.. because i know what my steel can do, and i did a batch differently, and they were cutting like garbage..

i sent some to Cliff to test, and he concurred.. it was garbage (relative to my normal)
I'd done a different cycle on the HT and suspected this was the issue, but it wasn't hardness or anything else

All his tests matched up with mine.. just not as good.. flaking, chipping etc..

after a lot of testing and experiments, because i was worried I'd ruined 60 knife blades, i finally worked out what i believe the issue was..

it was the only batch i'd ever laser cut, vs waterjet.. after grinding 1mm off the edge, the steel was normal again.. the Burn of the laser had caused unrecoverable damage, to a worse depth level than i thought it would be.. i'd not ground off enough of the edge steel before HT..

if the factories are using laser cutting, and dont intentionally make the edge 1mm+ more than is needed and grind it off as a precut cycle before HT then i believe this is what a lot of us may be experiencing, vs a bad HT.. different steels may have greater or lesser impact..

i only just remember this last night when i looked back on emails i had with cliff smiling smiley

i remember, because when i laser cut my slipjoints after i added 1.5mm of extra steel on the cutting edge to trim off because of this. grinning smiley

----------------------------------------------------------------------
It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen
Re: Edge Feels Sharp, Passes Sharpness Tests, Still Cuts Poorly
April 05, 2020 02:50PM
cKc,
That is also and issue, Benchmade does lasercut their blades.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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