Asymmetric Edge Resource Thread

Good Idea for this. I have been wondering how easy the asymmetrical edge would be compared to the convex edges I have now on all my Infi.

 

if i were to touch up an asymmetrical edge that just needed stropped, i would give it a few passes on my paper buffing wheel to get it back to shaving sharp. if the blade had a nick or needs a burr worked up due to a flat spot i would leave the flat side of the blade alone and just hit the convexed side on my belt sander just enough to work up a burr and then go to the paper buffing wheel to remove the burr. in the field or for thoes of you who dont have a belt sander, i would use sandpaper and only sharpen the convex side and finish off on a leather strop.

 

The Asymmetrical edge is awesome. I have a folder with the Asymmetrical edge.
Stropping will bring the edge right back to sharp. Or, go 10 passes on the flat side of the blade and then two passes on the beveled side. Then lightly strop.

 

:thumbup: :thumbup: :thumbup:

Thanks, Guy!

Here's mine:

1) Strop convex side on soft leather loaded with CrO to align/polish the bevel (then wipe off any CrO residue);
2) Draw flat side across ceramic rod 2-3 times with edge trailing;
3) Strop convex side again lightly on clean soft leather to finish.

 

ummmm... Resin, I was referring to the Asymmetrical edge.

 

Actually Guy hit this on the head!!! Well said, for that's what I've been doing on my ERGO's (those that have A-sym edge) and a rod or carbide on the flat and strop or sandpaper on the convex.

At least this works for me as well and mine will shave.

 

Richard sold me on his paper wheels. They leave a nice polished edge and fast. I use the paper buffing wheel on my shbm whenever it needs a touch up and love it.
j_d

 

My methods are very similar to those in RG's quote from Jerry which are attributed to Cliff Stamp. Especially the first paragraph.

The technique in the second paragraph is the same for me using a waterstone on the flat section. This angle is where the "magic" lies and retaining it is very important. I colour the flat section with a sharpie/marking pen and use a waterstone as water does not dissolve the ink and this is just eroded by the grinding effect of the stone. I use a jewellers loop to make sure the metal is being removed across the whole section of the flat grind ensuring that this is kept as per the original angle.... which as I say seems to be the most important thing in keeping the edge working brilliantly. It appears to be about a 9 degree angle.

I differ on the convex side as when I need to re-profile after a lot of use or after flattening the edge by clipping a stone .... I use a belt sander instead of sand paper .... I initially use the edge as it comes as this is usually excellent .... but following a tip from Will York I have taken the convex side a little higher and used a lot of belt tension for a steeper more appleseed convex curve. This seems to improve the geometry but go steady as you don't want to enable the edge to "roll" more easily. If I have a failing on my edges it is that I often take them too high wanting maximum geometry advantage ... then forgetting that the rolling effect when cutting into wood at 45 degrees negates this advantage if the edge rolls. You only need a slight improvement to what comes from the factory on the convex side .... the factory curve seems done to cope with guys chopping breeze blocks .... I don't do this .... but have found it helpful if you hit a stone .... although taken just slightly steeper the edge obtained is truly amazing .... my Basic 5 has this done to it and has yet to be in need of re-sharpening .... I just re-align the edge using a ceramic rod on the flat side .... it is definately one of the sharpest knives I have.

On my Basic 9 and the Basic 11 I will probably just do the section near the handle like this for fine carving ..... leaving the sweet spot on the chopping part of the blade as per the factory angles.

 

The convex bevel is on the right side of the blade with the blade pointed away from you, edge down. The convex bevel is the wide one.

 

:thumbup:

 

The angle of the flat edge is very accute ... around 9 to 11 degrees .... that angle is where the "performance" on the ASM edge seems to hinge .... if you are going to sharpen that side it is pretty imperative you get the angle right. Variations on altering the angle seem to lose performance .... go steeper and you virtually make it a chisel grind which is the worst error performance wise .... go more obtuse such as the angles on the sharpmaker at 15 or 30 degrees and you create a secondary bevel on the flat side. If I was to use a sharpmaker .... and I do use mine set on the 30 degree inclusive or 15 degree either side setting .... it is only to remove with a few passes the wire burr created from sharpening the convex side on my belt sander.

For me most of my sharpening is done on the convex side which is a lot "safer" to play with because if you take the convex curve higher or lower it does'nt have the same effect as altering the flat side angle in my experience. Then I just remove the bur with the 15 degree setting on the sharpmaker using the dark stones and a couple of very light passes on the white stones to give it a razor finish.

I was lucky in that I had Two Basic 9's and one still had the factory edge and the other a user .... a burr in the blade caused me to need to sharpen both sides and I got the flat side wrong .... I went finer than 11 degrees and it became too chisel like as a grind .... I mic'ed up the second spare and re-ground the flat side to the same angle using diamond stones on a very carefully set up Lansky system which was moved every 4 inches along the spine to ensure consistency on the edge .... then after that which was a long labour of love .... I used my finest waterstone to polish the flat edge having attached an angle guide for the correct angle ... the knife came back better than new ....but it was a lesson to me that the flat side is where the magic lies ..... the convex side is comparatively "robust" in keeping the performance on cutting if sharpening ....

I am not sure why this is the case .... but it appears that the angle of the flat side if done right enables the knife to almost self sharpen and remove slight rolls or dull spots in the edge when used in the right hand .... anyway .... saying it simply the edge lasts a "lot" longer when you get that angle right ..... but don't ask me why it is so critical or why that is the case .... but from lot's of use I can say it definately is ....

Maybe Jerry can chip in and add to this ..... I think only he must understand the ratio's of angles and why they are done this way .....

 

Guy,

A few thoughts...

All of my asymmetrical edges have improved in cutting efficiency as the flat bevel has been allowed to wear back and almost disappear altogether, with repeated sharpening/thinning of the convex side. I would not take any metal off the flat side of the bevel, and would not try to grind that angle back in--let it go dead flat, in other words. The only thing I do to the flat side is to lightly draw it across a ceramic rod with the edge trailing to re-align the edge, then strop on the convex side to clean up any burr. The micro-bevel this leaves is almost imperceptable. To restore the edge after a ding or other minor damage, I work on the convex side only and leave the flat side flat.

I've sent two Basic 5's in to Jerry over the years to have the points and edges thinned out for use as hunters, and have specifically requested that the convex edges be restored before sending them back to me. On neither of these did he re-apply a bevel to the flat side--the primary grind on the flat side goes all the way to the edge, in other words, with all the edge bevel on the convex side. These are fantastic cutters.

I think the flat-bevel side of the factory-issue asym edge may be the result of needing a finishing step that's not too time-consuming to apply, but meant to leave the least possible amount of bevel on that side. By hand, though, it's possible to improve on that by reducing the amount of bevel on that side even more--almost to zero. Anyone who's experienced the cutting efficiency of a full-flat zero grind to a really thin edge--the 6 degree per side primary bevels on the blades of Ed Schott years ago come to mind--will understand the potential here.

As for the convex-side bevels on the B11, they ARE shallower than on the original Basics, i.e. less curvature/flatter as you say. Actually, I think this may offer slightly improved performance but it may be hard to distinguish from the originals without doing controlled testing.

Most of the above is based on surmise and experience--don't really have anything more scientific to offer than my impressions.

Will

 

Interesting points Will ..... I know you have used Basic's for a lot longer than most .... my own experience from going higher on the flat side which made it more or less a convex single sided chisel grind was that the edge did'nt feel as sharp and perhaps burred over towards the flat side .... maybe I did'nt remove the burr fully to bring about a proper pinnacle to the edge .... but on the "pinnacle" issue ... for the edge to have a real "pinnacle" it felt to me that the slight 9 degree back bevel assisted in achieving this .... especially when polished with the nagurra slurry on my waterstone ....

Anyway ... I am happy to try what you say again and see if I just need to work on the burr a bit more .... next time one of my ASM edges needs re-profiling I will give it a go ....

 

The flat side still needs to be rid of burr, which is where a light pass or two on the ceramic rod does wonders, IMO. Lightly burnishing the edge with a strop on both sides after using the rod gives me the best edge. :thumbup: You may be achieving a similar result by polishing your 9 degree back bevel.

I'd say do whatever works for you, and if that means applying an acute-angle back bevel, so be it. Before settling on that, though, I'd recommend you try going to a full-flat to the edge with just a micro-bevel on that back side.