How to sharpen a knife

[aliva]

I use this guide only a couple of $

 

[motormech1]

I won't get into the endless ways to sharpen a blade as I think the useful ones have been covered already. Personally, I use a 600 grit belt on my 2x72. However, speaking to stropping blades, many knife makers use the dirty wheel of their buffer to take the burr off and polish the edge In lieu of stropping. Usually there's no need to add compound as the residual in the wheel is sufficient. It literally takes 30 seconds. I was taught it by a friend who learned it at a knife making school. Interestingly, J. Neilson, a master bladesmith, commented on an episode of Forged in Fire questioning why contestants spent so much valuable time on sharpening and described the same process. Just wanted to provide another way to skin the proverbial cat. Cheers.

 

[GeneT45]

There's a lot of really good science behind "advanced" sharpening (deburring - "sharpening" is easy). The biggest takeaway for me is that the best method to get rid of the burr varies with the steel of the blade. I strop with a flat leather strop, folded newspaper, or the abrasive-impregnated leather of my Tormek grinder. Interestinging enough, a few knives (notably a Kershaw that I like) lose sharpness when stropped such. A quick pass through the edge of a hardwood block however improves sharpness. I'm measuring sharpness with a BESS sharpness tester and a razor's edge tester (the BESS tells you how sharp, the razor's edge tells you if it's consistent across the blade, since the BESS is testing a dental-floss wide patch).

I dislike most power sharpening as I think it wears the blade excessively. Wet grinding might be an exception, but I still prefer Japanese waterstones, Norton wet stones, or Shapton stones. Once you understand it though, you can sharpen on anything.

GsT

Edit: egregious spelling error.

 

[motormech1]

I agree on the wear aspect. I wouldn't put a highly valued blade on the belt grinder. I'd definitely pull out stones. But for utility use blades of any sort, which is 95% of what I own) I'm straight to the belt. But I think the buffer for burr removal, if somebody already has one, is worth a try if you haven't regardless of the sharpening method you prefer. It's only really polishing. Cheers

 

[GeneT45]

I agree on the wear aspect. I wouldn't put a highly valued blade on the belt grinder. I'd definitely pull out stones. But for utility use blades of any sort, which is 95% of what I own) I'm straight to the belt. But I think the buffer for burr removal, if somebody already has one, is worth a try if you haven't regardless of the sharpening method you prefer. It's only really polishing. Cheers

It certainly can't hurt to try. My point was that it may or may not make the knife "sharper" depending on its composition. Some sort of testing is in order, and conclusions can only be drawn with respect to a specific knife or metallurgy (e.g. I'm pretty sure all my kitchen set will react that same).

GsT

 

[motormech1]

Yeah, I could see it not working well for certain applications. But so far I haven't ran into one. That said, I don't make a very wide range of knife styles nor use a wide range of steel....so far. Lol Always learnin' man.

 

[brino]

Interestinging enough, a few knives (notably a Kershaw that I like) lose sharpness when stropped such. A quick pass through the edge of a hardwood block however improves sharpness.

For us "dull-minded" types can you please explain......

How can stropping cause a blade to lose sharpness?
How does cutting(?) a hardwood block improve sharpness?

...and I guess, fundamental to this discussion, how do you define sharpness?

Thanks,
Brian

 

[GeneT45]

For us "dull-minded" types can you please explain......

How can stropping cause a blade to lose sharpness?
How does cutting(?) a hardwood block improve sharpness?

...and I guess, fundamental to this discussion, how do you define sharpness?

Thanks,
Brian

Both stropping and lightly cutting into a hardwood block are methods of removing the burr or 'wire edge', ideally without damaging the 'real' edge underneath. You lose sharpens (and longevity) when stropping folds the burr over the edge, or causes damage to the actual edge. Most often cutting a hardwood block gives the illusion of an improved edge, by making the burr ragged, but the blade then quickly loses its 'sharpness'.

You can see electron micrographs in this book: https://www.amazon.com/Knife-Deburring-Science-behind-lasting/dp/179626458X . The author (now deceased) had a great webpage where much of the information was available for free, but I don't even recall what it was called. If someone else knows maybe it can be found on the wayback machine or another archive.

I'm defining sharpness as low (quantified) push cutting resistance on a calibrated thread as measured on my BESS sharpness tester. This is a 'push' (not slicing) cut, so making a ragged burr shouldn't give an artificially low (good) number. I also check the blade with a razor's edge tester to see if I have achieved said sharpness uniformly. It's not a perfect system, but it does allow for quantification and objective comparison.

There are also edge longevity testers but I have not ventured there (yet).

GsT

 

[brino]

@GeneT45,
Thanks!
Brian

 

[aliva]

It's sharp when you can cut a single newspaper sheet with one light stoke