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High-Performance Blades Sharing ideas for getting the most out of our steel.

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  #1  
Old 11-27-2001, 08:13 AM
JHossom
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Let's Talk Edges


I like long smooth convex edges on my knives. I find these edge cut extremely well, and hold up better under extreme demands.

I shape my edges by starting with an edge thickness that might be about 0.040", though the steel above that edge might be a little thinner because of the way I hollow grind. I generally lay in a bevel of about 20+/- degrees, depending on the knife, size, and intended use.

All of this is done on slack belts, though I use one at high tension with little give and one at lower tension and more slack. Once I've raised a wire edge with 120 grit 3M 977 belt at high tension, I go to my looser setup and a 320 or 400 grit J-Flex belt to begin shaping how the edge will finally look.

The first thing I do is to knock off the shoulder of the bevel, using an extremely shallow angle (shallower is better, but leave a little room to go even shallower on the next belt ). In my experience, hard angles are points of high drag in cuts so I get rid of them entirely. After smoothing over the shoulder, I allow the belt to work it's way towards the edge, by slightly increasing the angle until I am almost but not quite at the edge. In effect I get as close as I can without getting there and raising another burr.

I then switch to a Trizact #16, and beginning at the most shallow angle I can get, I smooth out and semi-polish the whole curve, inching towards the edge as before, but this time I go to the edge and form a nice smooth even wire along the entire edge. Sometimes, I've had to go back to the 400 grit belt if the wire won't form, and do some more smoothing towards the edge. Once the wire edge is nice and smooth, I go to a polishing belt.

I use plain cloth belts that I get from K&G. Depending on the steel, I load it with either dark green or white compound (CPM-3V doesn't like green so I use only white on it). Beginning again at the top of the curve, I polish the whole edge, by progressing slowly towards the edge. You have to be careful throughout this process not to overheat the steel, using just one pass between dips in the water bucket. (with the Trizact belt, you need to dry the blade before returning to the belt, since these belts are not waterproof).

You have to be especially careful with the polishing belt, not to overheat the edge. As it gets finer, it is more prone to heating. The green compound in particular will overheat the edge in a hurry if you let it. Using ever lighter pressure, polish right out to the egde and you will see a VERY fine wire raised with the polishing belt. That's it for using the belt when that happens. I then strop the edge with leather, until there's just no hair left of my arm...

Sometimes, for reasons I don't understand, no amount of stropping will clean up the edge. In these instances, I'll use my 1800 rpm polishing buff with white compound and a VERY light touch to brush off the edge. That seems to always solve the problem, and I can't tell the difference between the stropped and buffed edges. I just don't like to buff, if I can get it done with stropping.

This edge, when done properly, is very strong and cuts better than any other edge I've ever used. There is very little drag in cuts, and it stays sharp for a long time. Since you inevitably increase the original ~20 degree angle to something greater as you finish with the 400 grit and #16 belts, you likely end up with a final edge angle of maybe 25 degrees. This may seem like a lot, and if you are making a small knnife you can probably start a lot lower (maybe 15 degrees or less), but there is nothing wrong at all with how this heavy angle cuts and cuts.

For sharpening I recommend running a ceramic stick along the edge from time to time. If it gets way out of shape, I re-edge my blades for free.

I've put this same edge on an $18 Ontario Machete and amazed some pretty good knifemakers with how well that blade can cut through sapplings and still shave. Considering it is 1095 steel at Rc50, that ain't too bad. I've had 6 of these machetes walk away with friends so far this year.

Give it a try and let me know what you think.
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  #2  
Old 11-27-2001, 08:19 AM
Don Cowles
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Great post, Jerry- my method is very similar to yours, but I wind things up with a Trizact 6 (after the 16) instead of a polishing belt. May have to try one of those!
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  #3  
Old 11-28-2001, 07:51 AM
JHossom
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Silence? Is this worth doing?
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  #4  
Old 11-28-2001, 08:53 AM
Don Cowles
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I know I'm not the guy you want to hear from, Jerry, but YES, it is worth doing. I think things are a little slow everywhere right now, but just having valuable information like this written down is worth a bunch. I see that there have been forty-some views of your post so far, and I would bet that everyone who read it came awaywith a better understanding of the process. Please don't give up!!!
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  #5  
Old 11-28-2001, 10:34 AM
Geno
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I slack belt mine to 600 grit on the belts, then buff the edges and get out the stones for that final edge.
It gives a great edge and lasts longer than any machine application I have ever tried.Plus it is easy to duplicate out in the field if need be. Not many people could duplicate a machined edge with a stone,and wind up reshaping the edge geometry.
Truing up on a stone and strop kinda breaks the knife in for normal use.
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  #6  
Old 11-28-2001, 05:40 PM
Bill Foote
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I use the same slack belt method-a 120 grit with max belt tension, then 220, 400 with loose tension, them 15 micron, 9 micron and finally a worn out 9 micron with green chrome rouge to a wire edge. I strop the wire edge on a thick piece of leather I have glued to a piece of granite. I first tried the slack belt on my Bader between the two inch rollers and the platen removed, but switched to using the slack area between the tracking wheel and contact wheel. I can see the edge better when I use the top part of the belt.Friends like my edge so much I'm constantly asked to sharpen their knives for them.
The edge looks nice and shiny, too. I have trouble keeping it very straight, though, for instance a wharncliffe blade. I sometimes use a diamond stone on that one.
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  #7  
Old 11-28-2001, 06:11 PM
JHossom
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Yeah, a wharncliffe is tough. The problem I have is with the lighter, flexible belts. They are impossible to run the length of the edge evenly on a wharncliffe, at least in my experience.

I stopped using those micron belts when I got so many belt cuts in one week I ran out of bandaids.

I'm a little older now; I might have to try them again. Sometimes, it's hard for me to write this stuff, because I change belts so often. Always looking for that magic combination that will make all this easy.
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  #8  
Old 11-28-2001, 06:13 PM
AbelKnives
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thanks for the information
i have not been able to put a shaving edge on my knives yet, i've tried and tried but it diden't work. i'll try you method exept i don't have the trizact or cloth belts.

by the way, anyone know where you can get cloth, trizact belts in 1x30 sixe belts?
thanks
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  #9  
Old 11-28-2001, 06:44 PM
JHossom
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You don't need Trizact or cloth belts to make this work. Just take it down to the finest belt you have and raise a wire edge. Then take your most worn out belt in your finest grit, and apply white compound to it. Get the wire to flash along the edge, then strop on leather. You might have to strop for quite awhile, but when that edge appears, it will pop hair for sure.

Watch your angle carefully. You might be using too steep an angle. For starters try maybe 15-20 degrees, and understand, that isn't much angle off the belt. Good luck.
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  #10  
Old 11-28-2001, 08:50 PM
Gary Mulkey
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I've been using a new method recently with good results. I take the blade up to 800 grit normally then turn the belt over and strop the blade while running the belt up side down. I then finish stropping by hand. This reduces the stropping time considerably.

Gary Mulkey
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  #11  
Old 11-28-2001, 10:46 PM
Rob Simonich
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Great info Jerry and the rest. I piced up an old knife at a garage sale here in Clancy for $1. I looks like an old Russel double edge sticker. It was pretty worn but very sharp, and had an edge very much like you describe. I was on my 4 wheeler headed home and stopped to let my dogs swim in the creek. I found a very smooth stone and wiped the edge on this knife a little and it would very easily float hair after I stropped it on my boot. I took that $1 knife home and with its 5" or so blade would sail right through 2 1" ropes. It also cut the pop can easily. I keep that knife in my shop and look it over when I think of edges. Whoever the previous owner was 50 to 100 years ago knew all about edges, what he wanted and how to get them. Impressive for a knife that cost a buck!
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  #12  
Old 11-28-2001, 11:55 PM
ERIC ELSON
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Great topic!


For my edges I first set a rough edge with a 400 grit slack belt, I dont worry too much about exact angles i'm basically just removing material. This BTW is the most nerve racking part of making a knife for me, something about bringing several hours of finished work near a moving belt scares me

I set my final edge on a Lansky *type* sharpener working through to a fine stone and then a quick stropping. I realize this is a lot more time consuming than using a grinder the whole way, but i am more confident this way and my customers can easily keep the same edge on the knife with minimal equiptment.

regards

Eric.
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  #13  
Old 11-29-2001, 01:29 PM
Jonesy7
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edges


That is a heck of an article. I have a Hossom sharpened Ontario machete and I have chopped up a lot of brush and trimmed trees and the edge geometry is what keeps on cutting. BTW it will still shave hair on most of the edge. And what gets me is there is no deformation to the edge either. It really is a tough edge to beat.

Jonesy
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  #14  
Old 11-29-2001, 09:02 PM
AbelKnives
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thanks for all the info you guys, i can't wait to try this out on a knife once i have the time!
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  #15  
Old 11-29-2001, 10:11 PM
DC KNIVES
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I tried something new, for me anyway.I bought a leather belt at the Guild Show.I got it for my small grinder, a 1" x 42" to try it out.After getting to the worn 400 grit,I switched to the leather belt and white compound.Light touch and it was pretty quickly very sharp.I was pleasently surprised.Don't know if these are made in 2"x48" or 2"x72".Dave
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