Compound on strop?

J-P SAN said:
How about these methods? Do they work as final step?:


http://youtu.be/iYVfW8Z1k5s


http://youtu.be/vvTo4O2rQJo
Click to expand...

The first vid demonstrating use of a ceramic to remove a burr (by breaking it off) is something I generally don't recommend very often. Not that it can't work, but it requires an extremely light touch (can be difficult for some, as regulating pressure seems to be one of the more challenging things to learn). Some steels won't always respond as well either. In particular, very ductile steels like 420HC and VG-10 at lower RC have very tenacious burrs, and scrubbing the edge on a ceramic often creates more burr than it removes, if pressure is just a little too heavy. And even at higher hardness (60+ RC), I've noticed ATS-34's burrs are still tenaciously nasty to deal with. If using a ceramic to remove burrs on these steels, I've always gently filed them down at extremely light pressure, and I never use the corners or edges of ceramics for this; always the flat face of the hone. The corners/edges of the hone concentrate a lot of pressure on very small portions of the edge, and that makes it doubly difficult to avoid creating a bigger problem.

The 2nd video, demonstrating drawing an edge through a piece of wood, will only work with extremely fine burrs in steels that aren't very ductile (burrs are brittle and break away easily). Again, 420HC, VG-10 and ATS-34 are basically the polar opposite of that, and they've just laughed at me when I've tried to remove burrs this way.

In both cases, the best way to remove burrs is to minimize their size in the first place. Keep them as small as possible; this means watching very intently as you sharpen, for the formation of the burr. Pressure is what does the most to form burrs, so lightening up the pressure as the edge becomes more thin is critical. Holding the edge angle is also important; if the angle is a little too high, it has the same effect of focusing too much pressure into the edge.

I'm not knocking either method shown. They'll both work sometimes, for some steels under specific circumstances. But knowing when/how to apply them is the tricky part. Burrs are always a LOT easier to deal with when they're as small an thin as possible. If they're very big and/or thick, dealing with them becomes much more tedious.

( Edit: BTW, I reacquainted myself with ATS-34's burr-prone tendencies this afternoon, while 'testing' my stated remarks about ceramics above. I have a custom knife in ATS-34, and I've long-believed this particular blade to be harder (RC) than any others I have in the same steel. After very, very gently fine-tuning the edge on it to shaving sharp via diamond hones, sandpaper, polishing on a natural stone and stropping, all it took was a couple of very light passes per side on the corners of the white rods of a Sharpmaker to make the burr rear it's very ugly head again. :mad: )


David
 
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How can I tell that knife does not have burr or wire edge anymore? When I know that I'm safe?
 
J-P SAN said:
How can I tell that knife does not have burr or wire edge anymore? When I know that I'm safe?
Click to expand...

In the end, the cutting will tell the tale. I test for burrs & wires by very SLOWLY slicing into the edge of a piece of phonebook paper. Use the full length of the cutting edge, from heel to tip. If the paper snags anywhere along the edge (watch to see where those spots are), there's likely a burr/wire. On the other hand, if the paper just slides over the edge without being cut, it's like not quite fully sharp. When you can do the slow slice through the paper consistently and repeatedly without slipping over or snagging in the paper, chances are the edge is in good shape.


David
 
One more question! Is it possible to remove burr/wire edge COMPLETELY by only using hones?
 
J-P SAN said:
One more question! Is it possible to remove burr/wire edge COMPLETELY by only using hones?
Click to expand...

In terms of reducing it to a level that doesn't affect 99.999% of cutting tasks, yes. That comes with practice and attention to detail. The reality is, there's always going to be at least some tiny bit of burr/wire left on a fully-apexed cutting edge. But you'd have to examine the edge with a SEM (Scanning Electron Microscope) to even know it's there. At that level, it becomes essentially moot anyway.


David
 
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