A New level of Sharpness - Push Cutting TP

Rickbw said:
I've been playing around with this test and it has been an eye opener for me. Stropping with .25 micron diamond spray on leather has always given me a great hair whittling edge but I was very surprised to find that it was terrible at the TP test. With some experimentation I found that stropping on CrO (the old stuff from HA) followed by clean leather was far superior to anything I could achieve with diamond stropping even when followed by clean leather. It was also interesting to find that the TP sharp edges are more difficult to whittle hair with because they tend to slice right through unless you are very careful.

My ZDP blade has given me the sharpest result, sliding through the TP as if it was not even there. The worst material has been S30V which is a bit snaggy no matter how carefully I prep the edge. I should note, however, that even a snaggy TP cut will easily whittle hair, tree top arm hair or pass any other test I've tried. The nice thing about the TP is that it gives very good feedback on edges at a level of sharpness beyond other tests. Why does it matter? Still asking myself that question!

My diamond spray is still the quickest strop to a useful edge but if I want the ultimate sharpness it is waterstones to 16K with a quick touch-up on CrO and leather. Thanks to Ankerson for a great test!

Rick
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I share your experience with S30V and TP. Even when I get it to the point where it can bisect it in two hole parts, it still feels more like it's tearing than really cutting through it cleanly.
 
idaho said:
What is easy when you hold both sides of paper! Try getting knife so sharp it will cut free hanging paper.
I can't, so far...
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THG said:
Well that's the same thing as splitting a hair with a coarse edge if you hold it on both sides... It doesn't really prove anything.
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Post your TP slicing videos then.

I have tried and you need to have a sharp and polished edge.
 
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I messed around with this a bit last night...

I will say that whether or not it's a true push cut... it definitely takes a higher level of sharpness to slowly pass the blade thru the TP in this manner, vs. the technique previously used. Those who doubt its effectiveness of testing a blade should try it.

I was wondering if you could post the "sharpening specs" for the blades just for reference in this thread (angle, level of finish, steel etc.) Be good info to have contained within the thread, IMO.

Good stuff!!

cbw
 
I can't believe you did that. According to Sheryl Crow, you just wasted two trips to the bathroom. :D
 
I've been doing toilet paper for at least a few weeks, and I think it's a pretty good test. I try to hold the blade more horizontally, and actually push cut it. With the blade held at an angle more vertical, it's easier. The extremely polished edge that will more or less push cut tp is too smooth to pass the three finger test, IMHO. You either get a push cutter or a slicer- again, MHO, and I haven't tried this with a bunch of knives. The tp that Ankerson is cutting does show a nice cleanly sliced edge. That is a very sharp knife.
 
cbwx34 said:
I messed around with this a bit last night...

I will say that whether or not it's a true push cut... it definitely takes a higher level of sharpness to slowly pass the blade thru the TP in this manner, vs. the technique previously used. Those who doubt its effectiveness of testing a blade should try it.

I was wondering if you could post the "sharpening specs" for the blades just for reference in this thread (angle, level of finish, steel etc.) Be good info to have contained within the thread, IMO.

Good stuff!!

cbw
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I think this is a good idea too.

I've used ZDP, VG10, M4, Aogami blue (or whatever Murray used in my neck knife) @12*-14*, finished with .25u diamond on leather, then a clean horsehide hone.
 
I made an attempt to to do a push cutting test similar to the other videos. Not quite to the level of Ankerson's, as you can see, I get some tearing, (I should have spent a bit more time), but thought I'd post it anyway, since the last cut (4th one) is a slice like the "old standard", I thought this demonstrated pretty well that it takes a higher level to accomplish what's being done now. Kershaw Shallot dated 4/08 so 13C26?, 14.3 deg. (measured since I went a little farther in than the standard settings) on the Wicked Edge sharpener.

[youtube]Q_35GT3ixqU[/youtube]

(I'd still be interested in the sharpening stats of the knives in the other videos.)

Thanks.

cbw
 
cbwx34 said:
I made an attempt to to do a push cutting test similar to the other videos. Not quite to the level of Ankerson's, as you can see, I get some tearing, (I should have spent a bit more time), but thought I'd post it anyway, since the last cut (4th one) is a slice like the "old standard", I thought this demonstrated pretty well that it takes a higher level to accomplish what's being done now. Kershaw Shallot dated 4/08 so 13C26?, 14.3 deg. (measured since I went a little farther in than the standard settings) on the Wicked Edge sharpener.

[youtube]Q_35GT3ixqU[/youtube]

(I'd still be interested in the sharpening stats of the knives in the other videos.)

Thanks.

cbw
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The Blue Handled knife is at 32 degrees Inclusive and sharpened to 6000 grit EP tapes with Mothers on it.


The Military is at 30 degrees inclusive and taken to 6000 Grit EP tapes.
 
That is impressive. Even more impressive would be cutting the TP with the blade edge at 90º to the plane of the paper, without any draw.

Whenever the blade is angled other than 90º to the paper, the effective bevel angle is lower than the actual bevel angle. This is a shearing cut, and is why the guillotine has an angled blade, and why woodworkers skew their planes when working difficult grain.

A knife that could push-cut Charmin at 90º would be ready to try the scimitar/silk scarf trick on. THAT is a video I would pay money to watch!

Bill
 
Believe it or not,I just did it tonight with a 10" bowie blade I've been working on.It's forged 5160 that I've been hand sanding. I ground this one insanely thin just to see how it would perform.I sharpened it before the test on a fine DMT and stropped the snot out of it on leather loaded with green compound.

My cut was slightly more ragged than in the video and there were a few pieces of fuzz left on the blade.Does this count?
 
R.H.Clark said:
Believe it or not,I just did it tonight with a 10" bowie blade I've been working on.It's forged 5160 that I've been hand sanding. I ground this one insanely thin just to see how it would perform.I sharpened it before the test on a fine DMT and stropped the snot out of it on leather loaded with green compound.

My cut was slightly more ragged than in the video and there were a few pieces of fuzz left on the blade.Does this count?
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Sounds good to me. :D :thumbup:
 
Ankerson said:
Sounds good to me. :D :thumbup:
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I'm really glad you posted this.I've been looking for a good way to test sharpness.Both my arms are nearly as bald as my head and my wife won't let me test on my legs.She doesn't want me to look any more retarded than I already do.:rolleyes:
 
R.H.Clark said:
I'm really glad you posted this.I've been looking for a good way to test sharpness.Both my arms are nearly as bald as my head and my wife won't let me test on my legs.She doesn't want me to look any more retarded than I already do.:rolleyes:
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No problem, I think it's a great test. :)

Now all you have to do is strop it some more until it cuts cleaner and there is no TP left on the edge. :D

A 10" blade is a lot of work.
 
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