From screaming sharp to butter knife dull I'm one cut?

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No1up

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Feb 27, 2016
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My paramilitary 2 was screaming sharp last night. I cut one rope and I'm sure it would have a hard time cutting through butter... why so?
 
Probably a wire edge, possibly a burnt edge depending on if you have sharpened it since the factory and what you used to sharpen it (could be from the factory too). Also if you have it could be too thin of an edge compromising the edge stability. Dirty rope could have something hard in it like sand or grit. We'd need more info on sharpening. Least likely, but still possilbe is a bad heat treat batch (probably less that .1%).
 
I know cutting manila kills a edge on a knife... depends on rope maybe or the actual edge to begin with.


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The pera 2 was sharpened on the KME with chosera stones up to 10000 then stropped. Any advice for removing a wire edge? Also 17 degrees.
 
If a new knife, and other than sharpening error, keep sharpening it, it should get better.
My new sage1 s30v came with a razor sharp edge that quickly disappeared.
With the 1st few aggressive sharpenings, I chased an almost elusive burr, that when finally conquered, quickly dulled.
Afterwards, It's now no longer burring so bad and settled in to a more lasting edge.
I feel it will get even better with more steel removed.
 
10k is pretty extreme for the steel, back it down to about 800 grit and try again.
 
Once you get past 2000 or even 1000 (if not a strop) you are going too far. You remove too much material and make it brittle. 800 or 1000 is as far as you should be going
 
No1up said:
My paramilitary 2 was screaming sharp last night. I cut one rope and I'm sure it would have a hard time cutting through butter... why so?
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Rope made from natural fiber is very abrasive, with silica and/or any number of other dirty/gritty stuff in it. Couple that with the possibility of a burr (wire edge) folding over, and it's not too surprising how a fine edge can dull in cutting it. Also, if the edge angle is relatively wide, such as 35-40° inclusive or higher, the drop-off in cutting performance will be extreme, when the apex itself loses it's crispness. It's a little easier to sustain some marginal cutting effectiveness at a narrower geometry, such as 30° inclusive or lower, even after the apex dulls a little bit.


David
 
Well it had DEEP scratches from the diamond stones that were bothering me so I cleaned then up with the Ken Onion Worksharp. Once the scratches were gone and the last 1/8th of the blade was even I moved on to the KME and the chosera stones.


I belive my problem would be that on the KME I spend some time on each side and don't really alternate stroks. Like 20 and 20, simply because I dread flipping the knife. Getting closer and closer to pulling the trigger on the WE
 
IMHO the edge was too polished and just lost its bite . To remove the burr raise the angle to about 18 degrees or 19 and do very light strokes from tip to heal.
 
REVDH said:
Once you get past 2000 or even 1000 (if not a strop) you are going too far. You remove too much material and make it brittle. 800 or 1000 is as far as you should be going
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Well stated, after 800 or 1000 max a few licks on the strop or if you have an old belt should give you a good longer lasting edge.
I have 4000 & 8000 water stones but only go that fine for my razors.After 8000 a half dozen laps on the belt & it's ready to shave with.
 
No1up said:
Well it had DEEP scratches from the diamond stones that were bothering me so I cleaned then up with the Ken Onion Worksharp. Once the scratches were gone and the last 1/8th of the blade was even I moved on to the KME and the chosera stones.


I belive my problem would be that on the KME I spend some time on each side and don't really alternate stroks. Like 20 and 20, simply because I dread flipping the knife. Getting closer and closer to pulling the trigger on the WE
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I hated flipping on the edge pro too, just because I rarely put the knife back in the same place . My edges really suffered because of this too . I would do 20 flip then 20. You haft to flip it and do less passes though . That's part of the reason I don't use jigs anymore because it's a pain to me to do 1 stroke on a jig flip do a stroke flip, but it's a must if you want the most out of your edges.
 
I don't think the WE is the answer to your problem. Like Jason said 10k is too refined for cutting rope. Keep your same angle you have now but drop down to 800 or even 400 and then try it again. The fg of the para2 with the 34 inclusive and a lower grit sharpening should make the pm2 cut rope like it's not even there.
 
But do guys think the edge would be lost after only one cut? The Wicked Edge would allow for strokes on both sides reducing a formation of a burr.
 
No1up said:
But do guys think the edge would be lost after only one cut? The Wicked Edge would allow for strokes on both sides reducing a formation of a burr.
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Yes if your edge was not really an edge it was a burr , your cut removed the burr.
 
No1up said:
But do guys think the edge would be lost after only one cut? The Wicked Edge would allow for strokes on both sides reducing a formation of a burr.
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Yes, with a burr or wire edge, it will dull in one cut... and it doesn't have to be rope to do it. It's all about burr/wire edge removal. (I do it similar to how Spartan00 described... raise the angle and a couple of light alternating strokes). It is easier on the W.E.... but you don't have to do it a bunch of times. Usually just a couple of alternating strokes will do it... not that difficult on the KME. Try just a few... probably easier than you think. (Even on the W.E., you still have to deburr the edge.)

Not doing it means your original issue was probably a burr or wire edge (especially if it dulled as fast and as bad as you described)... next time you test try just cutting some copy paper or light cardboard... these will quickly show a wire edge if there, without wondering if the media dulled the edge like rope can.
 
OP you can also deburr in a block of wood or even a strop . Run the edge lightly through some wood to pull that burr off . When I'm working with really coarse stones I have in the past went to a strop after my coarsest stone . Nothing like finish stropping just a couple strokes to make sure that burr is gone before I go to the next grit . CKTG sells a felt block for a couple of bucks for this .
 
No1up said:
But do guys think the edge would be lost after only one cut? The Wicked Edge would allow for strokes on both sides reducing a formation of a burr.
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After one cut on abrasive rope with a highly-finished (high grit) edge, it's entirely possible. Burrs can come in a wide range of sizes too, and even very tiny & thin ones can interrupt clean cutting. With the rope, I'd bet more of the issue is due to abrasion of the too-fine edge, as opposed to a burr; not that a burr couldn't be an issue though. Abrasive wear, by scrubbing off a fine apex, is a lot more common with polished edges used on rope. If it is just an issue of a fine burr folding over, some stropping could temporarily bring it back by realigning the burr; that'd be an easy way to verify if a burr is the problem. If the same sharpness doesn't come back with stropping, it's much more likely the apex has been rounded off due to abrasive wear, and it'll likely need some restoration on a stone to make it crisp again.


David
 
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10k is for Straight Razors not knives. Knives need that toothy edge because most things you cut are very abrasive, meaning it will wear down a finely polished edge in as little as one cut. The coarser the better.
 
Jason B. said:
10k is for Straight Razors not knives. Knives need that toothy edge because most things you cut are very abrasive, meaning it will wear down a finely polished edge in as little as one cut. The coarser the better.
Click to expand...


Exactly right. :thumbup:
 
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