The Paper Cut Test After Sharpening

[David Martin]

As an edge becomes both thinner (geometry DOES make a significant difference) and more polished, the sound when cutting paper will change from a louder 'ripping' sound (more coarse/toothy edge), to something approaching a whisper-quiet 'whoosh' in cutting the paper. Convexing & polishing the shoulders of the bevels will also tend to make paper-cutting quieter. I never realized how much the hard-edged shoulders of a V-bevel actually drag in a slice through paper, until the first time I smoothed & rounded them off, while essentially leaving the edge apex unchanged. Makes a big difference in the sound produced, and also in cutting resistance (more smooth/rounded & polished => much 'slicker' slicing).
David

Yes, I've noticed this as well. DM

 

[fmendez]

This is why I advocate SLOWLY drawing the blade through thin paper (like phonebook pages), while holding the butt end of the handle (I like to do this with knife held just between thumb and one finger). It's more difficult to influence the aggressiveness of cutting with the individual hold/technique, when held this way. The integrity of the apex (how crisp, how pure, how clean) will show up more here, and it'll effectively demonstrate both push-cutting and slicing effectiveness at the same time, using essentially the weight/geometry of the blade only.

More aggressive slashing and hacking at the paper is largely influenced by individual technique, much in the same way a golfer's distance and clubhead speed are influenced by the rhythm and fluidity of his own individual swing.

As an edge becomes both thinner (geometry DOES make a significant difference) and more polished, the sound when cutting paper will change from a louder 'ripping' sound (more coarse/toothy edge), to something approaching a whisper-quiet 'whoosh' in cutting the paper. Convexing & polishing the shoulders of the bevels will also tend to make paper-cutting quieter. I never realized how much the hard-edged shoulders of a V-bevel actually drag in a slice through paper, until the first time I smoothed & rounded them off, while essentially leaving the edge apex unchanged. Makes a big difference in the sound produced, and also in cutting resistance (more smooth/rounded & polished => much 'slicker' slicing).


David

The way you suggest holding the handle makes it, IMO a more difficult and rigorous test but it certainly will demonstrate a sharp edge, cutting through regardless of the paper's grain direction. how much does humidity which makes paper curl affects slicing the paper's edge? I'm also noticing that phone books are becoming scarce in my area and the remaining ones available use a thicker paper.

 

[lobo9er]

Didn't read through all of thread so maybe this has been covered....

I like the paper test to find burs,rolls and or chips. When the paper snags up it shows some sort of edge issue.

 

[Obsessed with Edges]

The way you suggest holding the handle makes it, IMO a more difficult and rigorous test but it certainly will demonstrate a sharp edge, cutting through regardless of the paper's grain direction. how much does humidity which makes paper curl affects slicing the paper's edge? I'm also noticing that phone books are becoming scarce in my area and the remaining ones available use a thicker paper.

With the phonebook pages, I don't think humidity plays into it much. I started doing this when living in central Texas a few years ago. It was MUCH muggier there, at times. I'm living in much drier New Mexico now, and don't see any difference in how the paper behaves. This is part of why I like using phonebook pages, because they've behaved very consistently (across two states, anyway ).

One thing about REALLY low humidity, here in the desert southwest: when slicing phonebook pages on really dry days, I've sometimes seen the paper strips will cling to and collect on the blade, with static electricity. The static seems to build up with repeated slices in the paper, more so when doing it with some speed. Sort of odd to see, but all the more fun.

If phonebooks are hard to come by, I've also found a lot of mail-order catalogs to serve reliably in their place. Cabela's seems consistent, and I've also received catalogs from Staples/Office Depot that are very similar.


David

 

[cchu518]

I think mag is correct. I've been reading his sticky over and over to uncover what mistakes I have been making and looking at jdavis videos

The style of sharpening that I have been doing works well to get a knife sharp but not finished as mag says. I've been applying a series if lighter and lighter strokes on the fine and the overall uniformity of the edges that I'm getting are much smoother now thanks and ironically the knives now slice paper! The original issue came down to my poor technique.

 

[David Martin]

cc, Yes, technique is important. I've noticed during sharpening a blade (420HC but most follow this pattern)it is first able to cut newsprint across the type and cannot slice up or down the print. After working it more on the stone (320grit fine India) it will began to slice newsprint in either direction, still, without stropping. Work it a little more and it will begin to cut thru wrinkles and no burrs present. DM