Sharpening prob

barrabas74

barrabas74

Joined
Jul 27, 2005
Messages
8,169
I usually dont have a sharpening problem but I do this time and its beginning to ware on my patience. I am trying to sharpen my AD and I am using the "sandpaper" method, I was just touching it up and went from 800 on up to 1500 and I get almost NO edge, it feels convex but almost dull. It feels like I may have rounded the edge but I made real sure that I didnt round off. Should I drop down in gritt and try it again? I was going to try my sharpmaker but the grind on there seems convex from the shop. Any ideas?
 
barrabas74 said:
I usually dont have a sharpening problem but I do this time and its beginning to ware on my patience. I am trying to sharpen my AD and I am using the "sandpaper" method, I was just touching it up and went from 800 on up to 1500 and I get almost NO edge, it feels convex but almost dull. It feels like I may have rounded the edge but I made real sure that I didnt round off. Should I drop down in gritt and try it again? I was going to try my sharpmaker but the grind on there seems convex from the shop. Any ideas?
Click to expand...

Barabbas74, I also have an AD with a convex edge... It would slice paper, but feel dull to the touch... I literally ran a finger down the entire edge last week with no cut at all. I think that the edge is just so smooth, it lost its "bite", so I use this rod from a cheesy knife sharpening 'kit' that I've had laying around, It's basically a fine grit steel, and i use it to lightly work the edge a few times per side after the mousepad & paper... helps a lot, and I won't be trying that crazy edge test with it NOW, LOL, as it has its bite back again. I hope this helps ya. :) ... Or maybe use some 600 or 800 grit paper just lightly on the edge after you get it how ya want it...?
 
I have noticed the wire edge on INFI is tough.
Look at your edge with magnification and see if it is still there...
 
You can also find a pesky wire edge with the "fingernail test." Take a finger that has any exposed nail and touch the tip of your nail to the secondary bevel with the flesh side of your finger facing the edge, nail side facing the spine. Slide your nail to the edge and see if it catches, or slides right off the edge. If it catches then you have a wire edge. If it slides right off, you're good on that side. Try the other side of the blade.

But I like using my 20x loupe to see the edge.

I have a cheapy Benchmade that I put a zero edge on for practice. On that one I think I feel the same thing you describe in this thread. It is polished all the way to the edge, and when you rub a finger on it, orthogonal to the edge, you can hardly tell it's sharp. But if you do a push cut it will slice like crazy. I agree with Jaxx that in my case at least it's because it's so polished that there are no teeth, and also the edge is much thicker than it needs to be!
 
OK yeah I think its so polished that it feels like its not sharp, I def can slice paper with it, it just does not have the "bite" that I am used to in my knives, I will try that steeling idea. It doesnt really shave hair though, so....hmmmmmm
 
something that you can do with convex edges that will tell you whether or not your actually getting the cutting angle you want - sharpen your knife with whatever convex method you want.

The permanent marker the cutting edge so its entirely black or red.

Then take your sharp maker, your edgepro, or whatever you have that has set angle markers, and set it at 21 degree's, 17 degrees, or whatever angle you wanted to get initially.

use 2000 grit stone or sand paper, something that wont dig into the steel.

and note where the permanent marker is removed. if you find that its removed at the dead center of your bevel, but no where else, then the actual cutting angle you produced via your convex method is actually more obtuse then the angle you initially wanted. if you find that its only taking off the marker at the top of the bevel, near the coating, then you produced a waaaay too obtuse convex edge.

more often then not, I have found that busse sharpens their knives to a 35 degree per side cutting edge angle, but you can quickly get it down to 21 degree's by removing the round convex nature of the edge. once you get it there, you can permanent marker the edge again and use the convex method, making absolutely sure to not remove material right at the very cutting edge, so that you ensure a 21 degree pers ide initiating cutting edge.



essentially - you can use your edge pro to determine the very initiating cutting edge angle without really modifying the convex. It's much easier to make a 65 degree included edge feel dull then it is to make a 30 degre edge included feel dull. and convex edges can often be deceiving with how the very initiating cutting edge can drop off and take on a more obtuse curvature.
 
Jaxx said:
I also have an AD with a convex edge... It would slice paper, but feel dull to the touch
Click to expand...

I have a HOGSJTACLE that is convex and it's the same deal. I worked the edge real well to 600 grit. It will slice paper great but feels dull. I had taken it to 1500 but there was no bite at all so I took it back to 600. I didn't see much advantage of going past 600, I prefer some bite for slicing rope and such.
 
Assuming it's still not sharp, are you rolling the blade across the paper on the end of the stroke? Drag and stop, then lift vertically or you'll just round over that edge.
 
attachment.php


a visual of what I was getting at. you cant really modify and understand what your doing unless you can understand and know what results your getting in the first place.

Given, practice makes purpose and experience is the greatest teacher, being able to check your results will speed up everything and make it a bagillion times easier.


Then again, I've never used a sharp maker, I'm used to the edge pro where you lay your blade on a table, making it hard to change the position of your blade which ensures that you get a truly consistent sharpening angle. I know that the lansky would work in with the method I described. If you have to free hand using the sharp maker, it might not work as well as I described above.
 
What are you using as a backing for the sandpaper? It could make a big difference. Try using something harder with a slight give such as leather. I agree with others that the edge can be polished to a point where it feels almost dull because it has lost its micro serrations. However, a edge like that should still be able to easily shave hair and push cut.

Are you following the same angle of the factory secondary bevel while convexing? Or are you reprofiling the meaty area just right behind the edge.

The edge of the AD and MS are very very meaty which makes them very strong. But the thick edge also makes them inefficient cutters. If you are following the obtuse secondary bevel while convexing then you could have easily rounded off the edge. If you are removing metal right behind the secondary while convexing then it would be harder to round off the edge. Well, at least until you get the the point where both sides converge at zero.

Note that at some point while convexing..... the meaty area behind the edge and the secondary bevel should become a large convex and converge to zero at the edge. Hope this helps and give you some ideas.
 
I agree with ban on using something with either reletively little give - or using very light pressure. If your using a backing that readily crushes downward, you are more likely to unwillingly curve the sand paper around the edge, creating a very steep curve at the initiating cutting edge. it will look like your bevel is correct, but because the foam curved around the edge heavily, the cutting edge itself is very dull....
 
I am using a leather strop and putting the sandpaper on that, I will steepin the angle and see what happens.
 
If you are using a leather strop then it should be good to go. I would like to suggest that you start off with 60 or 80 grit and work the area about 1/8-1/4" right behind the edge. Work towards removing that metal from that area until it converges all the way down to the final edge. Start going up to 120 grit as soon as you reach about .01. You can start going up in grits sooner but it will just take more time to converge the edge to zero as the higher grits will remove metal much slower. I usually stop at around 600-800 grit then just strop with Chromium Oxide. By the time you are done the convex edge should be about 1/4" high from the zero edge on thicker knives. .
 
I'll give it another go and start lower in grit, say 80 and work up to 600 and see how she goes. Thanks for all the help guys!
 
You must log in or register to reply here.
Back
Top