sharpening confusion

AF

Joined
Jan 14, 2000
Messages
6,017
I tell you, I have basically been mystified with sharpening since I began in earnest to master the feat a couple of months ago. I have had some success and a fair amount of frustration. As I struggled to sharpen my friend's mini buck tonight, using the Lansky, I noticed that I had chipped the edge in a couple of spots. Yet, it still didn't feel very sharp. (20 degree back bevel and 25 primary). I switched over to the Sharpmaker 203 and achieved what felt like a decent edge, beginning with the coarse ceramic and ending with the fine. I never raised a burr, I don't think. The edge would not cut paper with any smoothness. I tried to shave some arm hairs and succeeded. I didn't have to really scrape the arm with much force. What happened?
Here's a related question I have. Why is it necessary to get a burr on both sides of the blade? Is it done simply to keep the edge centered?

[This message has been edited by AF (edited 05-19-2000).]
 
First off, welcome to the forums and the joy of sharpening knives. The reason why it is so important to get burr on both sides of the edge is simply this; what makes an edge sharp is having both bevels meet each other, then smoothing each bevel. Whether or not the edge is centered is of little importance, other than aesthetics. When a burr forms on the edge, that means that the bevel you are grinding on has met the other side. Its important to raise a burr on each side so that both bevels have met. Many times the second burr will form almost immediately, and other times it will take longer than the first. The thing to remeber is that raising a burr on both sides is probably the most important step in sharpening. Unless both bevels meet, no matter what you do afterwards you can't have a razor sharp cutting edge.

My advice to you is to get a cheap bench hone from your hardware store that has a very coarse side on it. One thing that many people overlook while sharpening is the fact that how you get the burr has no bearing on how sharp the knife will be. What's important is removing the metal. You can speed up the process and get a sharper knife by grinding your knife at a shallow angle on a rough bench hone till you get a burr on each side and then proceed to smooth the edge with your sharpmaker. You don't have to hold a precise angle on the bench hone, just make it shallower than the angle on the Sharpmaker. Feel free to e-mail me if you have any other questions, or if this is a little too confusing to follow. Good luck, and don't give up!
 
There is some really good stuff to read here---http://www.bladeforums.com/features/faqsharp.shtml
 
Thanks guys. I read the Talmadge FAQ and Juranitch's book. It's all interesting and informative reading but actually getting results has proven difficult. I do enjoy sharpening though, and will stick with it. I think at some point I'll invest in a razor edge system with the benchstones and the hone guides.
 
One other thing, unless my sense of geometry is skewed, the Lanksy does not provide a constant angle- it varies as you move along the blade, with longer blades having more variance. The angle chages more at the tip or for a blade with a lot of belly. Am I wrong? Also, can the Lansky stones be cleaned with Comet? On the directions, it says to just wipe them with a rag but that doesn't seem to work great.
 
AF --

My very strong advice is that if you are getting frustrated, then you should switch to practicing on a knife that is a bit easier to sharpen. A spyderco delica will cost you only around $30, it's a wonderful little knife, and is easy to sharpen. Buy one, use it hard for a few weeks, then sharpen it. This time, absolutely do not stop until you get a burr, first along the entire length of one side, then the other. If you don't get a burr, there's simply no way to be assured you've gotten all you can out of the edge.

Also, you should lean heavily on the magic marker trick. It will at least show you how close you're actually getting to the edge. Sometimes I'm convinced I'm at the very edge and a burr should happen any second now, but then I use the magic marker and I see there's much more edge left than I had thought. It keeps me from getting frustrated, because I can keep track of the magic marker, and be able to visually confirm that I'm making progress.

Joe
 
My Lansky stones were (are) clogged almost from the first strokes on the blade. And yes, the angle is not constant. The Lansky was good for learning (using 2 or 3 times) and changing the bevel on my Benchmade. However, I have scrapped the clamp and the rods and just use the stones. I will be getting some regular stones without any gadgets soon. DMT brand looks pretty good. Don't be afraid to try some free hand sharpening. I'm as new as they come and I'm getting the hang of it pretty well.
 
A question I've always had about burrs might get a response here so I'll try it. Once you have achieved a burr on both sides with say a medium stone, do you then work the fine stone until you again get a burr on both sides and then again with an extra fine stone?
Thanks,
Davy
 
Davy, I don't know for sure whether this is right or not, but I have been raising a burr with each successive grit stone that I use in the sharpening process. I use the Edge Pro system now which makes the process much easier than when I used my Lansky. For most of the knives I've sharpened with the Apex thus far, I usually start with the 180 grit stone (as I've been reprofiling the edges of most of my production knives), then I move on to the 220, 320 and 600 grit stones. With each of these stones I've been raising a slight burr and after the initial reprofiling is done, the successive higher grit stones seem to raise a burr fairly easily. Again, I don't know if this is right or not, but it seems to be working.

------------------
Semper Fi
 
Short answer: once you raise a burr, the entire remainder of the sharpening process is dedicated to grinding it off!

Remember what the burr tells you: you have reached the end of the edge, to the point where the edge is so weak it spurts out and over. Once you have the burr, you know your edge bevel has reached the end. Now, you want to get rid of the burr, because the presence of the burr weakens the edge. As you go to finer stones, there is absolutely no need to keep re-establishing the burr. Just switch sides between every stroke, making your strokes lighter and lighter as you progress.

My last few strokes, on the finest stone, are very very light. Often, there is still a tiny bit of burr left, that you absolutely can't see or detect. Well, you can detect it -- if your knife seems razor sharp, then you cut just a few things and it's not razor sharp anymore, you probably had a little bit of burr left that broke off. Even steel that gets bagged on in this forum -- like 8A -- should stay sharp for a while.

You can do two things to get rid of that last piece of burr. First, you can do a double-grind. By this, I mean you will increase your sharpening angle a couple of degrees, and take one or two very very light strokes per side down the stone -- don't do this too hard, or you'll re-establish a burr! Increasing the angle a couple of degrees for the last strokes grinds off the remaining burr, and makes the edge a bit stronger. If you're sharpening with the Sharpmaker, and you did the edge at 20 degrees, you can do the double grind by tilting the spine of the knife just slightly towards the center of the V, instead of exactly straight up and down -- that will increase the angle a couple degrees for the double grind.

You can also do a light stropping to get rid of the burr. If you strop for too long, you will not only get rid of the burr, but you'll razor-polish the edge. That's good if you want to razor polish the edge, but most people have more use for a coarser edge for better slicing.

Joe

[This message has been edited by Joe Talmadge (edited 05-19-2000).]
 
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