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TOPIC: Looks sharp but isn't????

Looks sharp but isn't???? 9 months 3 weeks ago #14633

  • Grift
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Not sure sure which forum this should be in so if this isn't it please feel free to move it.

Here is my conundrum. I just got done sharpening a Pro Tech prototype folder I sometimes carry. I wanted to get a really razor sharp edge on it so I reprofiled the edge to 17.25° per side (checked on angle cube). I used a sharpie and looked to see when I hit the apex using a loupe. I progressed from 100 up to 1000 applying very light strokes with the 1000 towards the end to get most of the scratches out. I checked the edge with a loupe and I did a very good job of getting all the scratches out. It had a milky mirror edge all the way to the apex looking through the loupe. I figured that was good enough for the night and I might just strop it tomorrow. To the touch it felt pretty sharp as well. I took it out of the vice and proceeded to try and shave my arm like I always do and it wouldn't shave at all..!!!

I don't understand? It looked and felt to the touch like it would have been as sharp or sharper than the edge I've put on other knives that were indeed shaving sharp, yet it wouldn't shave. Anyone have any ideas as to why this is the case. I don't get it......
Last Edit: 9 months 3 weeks ago by Grift.
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Looks sharp but isn't???? 9 months 3 weeks ago #14636

  • DAUG
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Grift,

Are you progressing to a burr on your re-profile or are you just using the sharpie mark elimination method to indicate whether you've reached your edge or not? The burr is important, since it indicates you've reach the edge of any side you're sharpening. Do you need a burr at each stage of your progression? Not necessarily, in my experience it's only required at the initial re-profile progression, since I just use progressively lighter pressure at higher grit levels.

Conclusion, if it does not feel sharp to the touch at your final progression, then you may have not reached the edge initially. So check it out!
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Re:Looks sharp but isn't???? 9 months 3 weeks ago #14637

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Well I was pretty sure I had a burr. I used the loupe (small jewellers magnifying glass) to check if I reached the edge. It showed that the scratches went to the very tip apex of the edge. I didn't feel for one this time since I was just looking for it instead with the loupe. I dunno, maybe u didn't get a burr, but It looked like I did and the edge felt as if I had...
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Re:Looks sharp but isn't???? 9 months 3 weeks ago #14638

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Do this to ensure you've created a burr, fold a damp paper towel in half and swipe the opposite side of the edge you're profiling. If a burr has occurred it will leave tell tale signs of cotton strands on that edge. If not, then you haven't reached the edge yet. You can use a cotton ball as well, but a paper towel will work just as well.
Last Edit: 9 months 3 weeks ago by DAUG.
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Re:Looks sharp but isn't???? 9 months 3 weeks ago #14640

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Yea I'll try to detect a burr on it tomorrow and resharpen it. Shouldn't be too bad since I got the angle set and I've got to be really close to getting a burr already. Is the wet paper towel the best way to detect a burr? Is there any other ways that are better? If there is another method that makes it easier to detect even if it is something specialized I'd need to buy I'm all in at this point.
Last Edit: 9 months 3 weeks ago by Grift.
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Re:Looks sharp but isn't???? 9 months 3 weeks ago #14642

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No need to buy anything more expensive than cotton balls or paper towels to test for a burr. You've got all the tools necessary to successfully achieve the edge you want.
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Re:Looks sharp but isn't???? 9 months 3 weeks ago #14645

  • razoredgeknives
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A few Things that may be the culprit:

1. You may have a burr that still needs to be removed. Try shaving arm hair on the other arm. If it does shave, this would indicate that you have a burr on one side that is not present on the other side.

2. Take a very bright light (preferably use the sun on a sunny day) and turn your knife edge up and look down at the edge. See if you have any bright spots on the edge... If so then you did not truly apex it. You need a burr, which you can actually create with the 600 stones (no need in going all the way back to 100 if you are already close)
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Re:Looks sharp but isn't???? 9 months 3 weeks ago #14646

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Do I need a burr with every stone? I thought I only needed to create a burr with the first stone, then work both sides evenly through the rest of the stones. I dunno maybe I just been getting lucky in how I was doing all the other knives, but they all had scary razor edges.

One more thing while I have some of you knowledge guys attention. I haven't stropped every knife but a few I did at first had an even better edge. I did a couple that actually got duller after the strop. I have been stropping at the same exact angle as I used with the stones but used very light strokes. Should I change the angle for stropping since they are softer?
Last Edit: 9 months 3 weeks ago by Grift.
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Re:Looks sharp but isn't???? 9 months 3 weeks ago #14647

  • cbwx34
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You're right, you only need to create a burr once, not with every stone.

I've come to the conclusion that stropping is sort of "user dependent"... in other words experiment and use what works best for you. That being said, Clay has tested and taken some microscope pics showing that stropping at a 1-2 degree lower angle will still contact the edge and improve it.
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Re:Looks sharp but isn't???? 9 months 3 weeks ago #14650

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Grift wrote:
Do I need a burr with every stone? ......

One more thing while I have some of you knowledge guys attention. I haven't stropped every knife but a few I did at first had an even better edge. I did a couple that actually got duller after the strop. I have been stropping at the same exact angle as I used with the stones but used very light strokes. Should I change the angle for stropping since they are softer?

As cdwx34 indicated, try to create the burr only once otherwise you're applying too much pressure and removing more metal than necessary - although to some the latter is less of an issue) on subsequent progressions.

As for dulling the edge after stropping, I suppose it can happen if the angle is close to the original set angle, but just off by a few degrees (about -[0.5-1.6] range). I've experienced this a few times with my WEP (I), since the arms have more play than the WEP (II). Being off by that much can mean not polishing the desired edge as oppose to the sides near the edge. And it becomes more apparent the thicker the blade you're working on.

As for the WEP (II) I haven't experience dulling a blade as yet and I suppose it's because of the tighter arms on it. So I'll make sure to check my progression angles are > or = to the initial set angle and keep them that way throughout the progression process. This way it is always contacting and hence polishing the edge.

Hope by now you've identified the cause of your dulled edges and get them corrected to your desired result. Good luck!
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