Sharpening: doing something wrong

Svashtar

Svashtar

Joined
Dec 28, 2003
Messages
4,793
To explain myself, I grew up sharpening knives on an oilstone (my dad used oil on his Arkansas stones, so that's what I did then and still do; he left me a set of 8" medium, hard and black hard Arkansas stones in cedar boxes that are really nice), so understand the basics. But it wasn't until I talked to Yvsa and Nasty at Gin's house in April, and saw Yvsa give a great convex edge to my Cherokee Rose, that I understood that kind of sharpening. I have just been doing a few passes with a tapered diamond steel to sharpen up some of my khuks, but have two khuks I am sending to my brother, so wanted to really do them right today.

The first one is a 15" wood handled AK from Amtrak, and it is butter knife dull. Great overall knife, just really polished dull. I used the same sharpener Yvsa did his demo with, which is a DMT diamond hone (black/blue). I went slow, with the edge facing away from me, rolling the knife edge up a bit and towards me as I pushed the hone, as I remember Yvsa doing, probably for close to an hour. Working to get a burr on the back side of the blade.

Finally I got a good burr along the entire back edge that felt really good, so I turned the edge to face me, and trying to keep the same angle overall, I rolled the edge up and away from me and worked it with the hone. I was feathering/marking up the blade more than Yvsa did, but I had the inside curve to deal with, and figure I can always try and polish it out, or easier yet just give it a satin finish when I'm done.

Anyway, after I got the burr out, I felt the edge with my thumb, and it hardly felt sharper at all! Any idea as to what I did wrong? I have garnet paper and a piece of mouse pad, but thought this would be a lot faster. Bottom line is after a couple of hours, and marking up the blade quite a bit from my efforts, is that the knife is only a little bit sharper than it was before.

I am planning on buying a belt grinder down the road, but I'm not going to do that until I can do it by hand first, so that I understand the process.

Also, this is the most I have used this blue DMT hone since I bought it, and in the middle where it was rough to the touch, now it is completely smooth. I have some DMT bench hones for my 4" folders, but those have not been used this hard. Despite the smooth feeling now, I am assuming it is still working, although frankly I can't tell. I heard that these are supposed to cut better the more you use them, but that kind of runs counter to what you would expect. (?) Again, thanks for any information. I actually figure I'm pretty close, but am just making some basic mistake.

Thanks,

Norm
 
We'll see what Yvsa says, but maybe you're doing too much?

When sharpening, I always pretend I'm spreading peanut butter on toast, and try to give it just that much thought and physical force. Unless there's a damaged edge, it shouldn't take long at all.
 
It is much easier to sharpen by producing a constant angle bevel edge on a knife blade. If I want a chopper, then I just use a larger included angle between the angle formed by the blade and the stone.
I have multiple sets of oilstones and waterstones. You can get good results using water on Arkansas stones, and I just got a Norton Lilly White Washita that works great with water.
A bevel egde works better for slicing, but a convex edge is likely to last longer when chopping. It has always been traditional to use a convex edge on axe blades - you take the stone to the stationary blade.
I am conservative and lazy about sharpening, and simply modify the angle between the stone and blade to suit intended purposes.
My guess is that it is hard to sharpen and generate a constant curvature - you may be changing the angle and then eliminating the sharp edge with subsequent sharpening.
It shouldn't be like doing a katana using old-fashioned methods. If you are spending an hour at it, then you are probably erasing your progress as you go....by increasingly rounding the edge over and eliminating prior work. If the edge is too soft, then finer stones are a waste of time.
 
Norm I suspect that you just need to lighten up.;)

If I were really ornery I'd leave you hanging with that a while but I'm in no mood for playing today so I'll tell you what I mean.;) :D
When you get the final burr on the opposite side of the blade you started on then it's literally time to "lighten up," with the hone that is.
Just barely kiss the edge with a very slightly increased angle just a bit on the last few swipes on the hone and see what happens.
If you have a set of crock sticks you can do maybe 3-5 swipes on a side using them and then when you strop the edge the microbevel will disappear back into the convexed edge.
It's been a while since April and we've both slept since then and some of the nuances in finishing the edge may have been dreamt away.;)
I sometimes have the same problem and have to remind myself that lightly is better. You're a good sized ol'boy and are maybe using more pressure than you realize.;) :D

Use a light stroke on the strop as well. Nasty brought up a good point the other day when he said that the strop could as easily dull an edge as it can sharpen by using too much pressure. The leather rolls back over the edge in a reverse manner when too much pressure is used.
If worse comes to worse try using a piece of cardboard to do the final stropping with as it doesn't have the give that leather does.
The problem can be that you keep rolling the microburr back and forth from one side to the other without removing it. That's the idea of the increased angle at the end.

Dayum I hope this makes sense. I've been in a great deal of pain the last couple of days and am under heavier medication than normal, probably shouldn't even be posting.:grumpy:
I see my Dr. in two more days!!!!:thumbup:
 
Yup...lighten up.

The low pressure needed is surprising. The thin pale grey backing for legal pads makes a great strop. When in Ogden once, I showed Vampire HunterD (Dan) how to strop on the road with theyellow pages...just opened in and laid it on the desk and stropped a couple of edges right up to hair popping. He later commented here on it...

I also suspect that those edges you are having trouble with are the better blades.
 
Thanks very much guys! Yep, I went after the burred side just as hard as the first. Probably used way too much force on both sides, so in theory I'm just working over and over again to move the burr from one side to the other. I know Yvsa did not spend hardly any time on the burr side, but I obviously am just making more work for myself.

I'll work at it today and see if I can do better.

Thanks again!

Norm
 
Another good trick is to run a Magic Marker along the edge. You can then see exactly where you're removing metal.

The paint section of the auto supply store has some very fine Silicone Carbide waterproof papers that do a good job when backed up by a strip of mouse-pad. 2,500 grit will give you a mirror polish. :D
 
I actually had to take a semi-smooth single cut file to the edge of my 18" WWII and draw file it (hold the file perpindicular to the edge and run it back and forth parallel to the edge) first. Then I went and got a 2' length of 1 1/2" dowel and covered half with 220 grit and the other half with 400 grit. I also have 600, 1500 and 2000 grit papers, as well as a few squares of emery cloth. Then I use a double sided wooden handled strop loaded with 0.5 micron chromium oxide that I picked up from Lee Valley. Now it's acceptably sharp. Like DDean and a few others have posted in the past, sometimes you need to remove a bit of metal to get to the good stuff.
 
Norm you need to go after it as hard as you can to get the first burr up. And you can go as hard as you can to get the second burr up if you're convexing the edge for the first time.
It's when you get the second burr up that you need to settle down.;)
Bri's suggestion of the Magic Marker is excellent too. I use that when a blade is giving me trouble and nothing I seem to do is right.

I applaud you're wanting to sharpen by hand before you go to the belt sander. Once you learn to sharpen it's like any other piece of knowledge; no one can take it from you ever!:thumbup: :D
Our Mr. Teach is spot on as well. If the edge isn't down to the good stuff it's more difficult to sharpen as the softer steel is easier to push from side to side.
The steeper angle will help correct this though.
But probably the only place you will ever run across that is with a Nepalese Khukuri or other indigneous made edged tool.
 
I actually spent 4 hours trying to put an edge on knife DK made for me. I was just so pissed off that I gave up. I wanted to use my fine eze lap stone to put a convex edge on it. It just wasn't working. I know it can be done but the best I got was an edge you could work with but couldn't slice paper.

So I caved today and used the mouse pad. My results with this have been 50/50 at best. But, I was able to produce a good cutting edge just short of shaving.

Right now I'm in the process of using my lansky knock off shapening kit to try and convex my 18" WWII with flat stones. This has been much easier than my knife because the blade is so much bigger.

I really do think that a convex edge is easier to maintain than your typical V edge. On my kumar karda, its my most successful sharp job, I find it very easy to hit it with a cardboard box , notepad, pantleg, palm, whatever, and keep it nice and sharp.

Thanks for the tip to lighten up, I think that this has been my major problem in the past. I always have a hard time determining which angle to use and how hard to push.

- D
 
I figure once you get a burr on one side, just try to minimize it as much as possible, don't bother reworking the whole other side till the burr flips over all the way. Use a light touch and DON'T trust yer thumb on how sharp it is, it's a useful tool to use to periodically check to see if stuff is going as expected, but also shave a small bit of hair with and against the grain, and cut through a sheet of paper to make sure it'll cut without tearing or getting hung up on nicks.
 
DannyinJapan said:
Id pay for a dvd with all of these sharpening techniques. I suck at sharpening.
Click to expand...

DIJ a DVD might be of some help but I doubt it would really be all that. The main thing is to work on one side until you have a full length burr all down the other side.
Then flip the blade over and work on the burr side until a burr is formed on the opposite side.
Then lightly hone the burr off. That is *Really* the *Secret* to sharpening anything.
And it's more a matter of *feel* than it is technique and the *feel* isn't something that can be taught on a DVD.:(

It doesn't matter whether it's an angle, convex, concaved, or what as the edge will take care of itself.
People that have never been shown how to sharpen will automatically sharpen a convexed edge. It is just human nature.
 
Even though I've only been sharpening kitchen knives for years, this thread was inspiring enough for me to put a good edge my 9" baby Chitlangi. Sharpening a khukuri is a lot like sharpening an axe. In other words, not a good beginner project. Especially a tiny curvy Chitlangi that has to stay pretty for pics. Luckily, it was a case of the edge being buffed off, so it wasn't too much work. Kitchen knives are so much easier.
 
Well, I dedicated the whole day to this, and it seems to be time well spent. I ended up getting a good "tacky" working edge on the AK, that is as close as possible to the edge on the Rose as I can make it. Not a super fine razor edge, but seems to be a good solid sharp working edge. (The blue DMT is way smoother now, but I'm hoping it takes more than this to wear these out.)

The second knife I'm sending him is a nice Sher 16.5" WWII. These are to be his first khuks, so I wanted to do them right. I did that one as well, although as the blue DMT was not seemingly cutting as much I used the black side for a while, and then switched back to the blue.

This one seemed to sharpen up way faster, and in looking at the knives I think it was just because the AK has such a fat bevel and so much metal to remove that it was way more work. The WWII was so easy to sharpen up, and I marked up the blade hardly at all, that I can't believe how hard I worked last night on the AK.

Not wanting to leave well enough alone, after dinner I used this EZ Edge device for the first time for my 4X36 that I bought a couple of weeks ago, after reading about it here. Very well made quality piece of work. It took some tweaking with the belt tension, but I got it working, and it worked _great_! I should be experimenting with my own knives and not the ones I am sending my brother, but thought I would just do a couple of passes, and you would not friggin" believe how fast this thing cuts. The highest grit I could find for my 4X36 was a 120, and it cut like a carbide saw on steroids I swear. I removed too much metal at the thicker part of the blade just in front of the cho, and freaked a bit, but then went to the back side and compensated. That was in the deepest curve of the AK, so that was expected. The rest of the blade turned out OK. I can't believe how fast this slack belt worked. Essentially I guess what I did was to cut a new larger convex bevel on the knife. It was good before, but now it looks just like my Blackjacks as far as the edge contour, so I think that's good.

Then I installed the 4X36 leather belt that I also found out about here, and it was so tight the motor would not turn. I put it in a spreader clamp for two hours to stretch it out, which made it better, but it still wouldn't work. Figured out that by opening the blade tension lever the whole way, starting the motor and then slowly closing it as the belt got up to speed, it ran fine. I coated it with green chromium oxide, and cleaned up the rough edges on the bevel in about 3 minutes flat. I am totally stoked that for more open blades like this 15" AK and WWII, that the 4" sanding and leather belts work fine. I would have some trouble with an M43 though...

Finally I used a loose canton flannel buff and white rouge to clean up all the marks on the blade, (very carefully!), and this knife is so damned sharp it is scary! I have gotten beveled edges this sharp after much work on a hard arkansas, but nothing like this so fast. I'm gonna have to put a disclaimer in the box with these knives. (-:

Now, I'm in sharpening mode, but I'm going to start by forcing myself to put away the 4X36 for a while, and do at least 3 or 4 more by hand so that I can really get it down and make sure this wasn't a fluke. I'm also going to see if I can find a higher grit than 120 for the 4X36 for when I do go back to it, but Sears seems to have just 50 and 80 and 120.

There's the 25" gelbu and a katana, a manjushri and a Tarwar I want to try for big blades, but that's a lot more work, so will go slow there. Screwing up a 15" AK is one thing, but not a manjushri!

The great thing about the heavy leather belt is that it totally polished out any areas of the bevel where I held the sander a bit too long. It's not perfect, but for a first attempt I am not displeased. :thumbup:

Like I said, a day well spent to learn knew skills. Thanks for all your help, and for what it's worth I'll do my best to pass this info along in the future to others as well.

Regards,

Norm
 
Those belt sanders are nice, aren't they?

A good compromise is to do large blades and swords on the sander and the little guys by hand. It doesn't take me too long to sharpen up a folder on the Spyderco hones but doing a sword like this is a day long evolution. I don't believe that the two sharpening methods are mutually exclusive, either - many of the fundamentals remain the same. (Maintain a consistant angle, raise a burr, etc.)

I've noticed that the leather belts loosen right up after they get hit with the stropping compound. Something in the base (wax?) seems to soften the leather.

I doubt that your brother will mind the experimentation.

Invest in some Band-Aids. You may be needing some shortly.
 
Petroleum base vs. natural wax base. Petroleum deteriorates leather. I think I said this in another post recently.
 
You did indeed, Nasty.

Are those the usual bases for stropping compounds? Petroleum and/or wax? For all I know it's my little knife elves sticking the chromium oxide particles together with chewing gum. PFM, as far as I'm concerned. :)

I guess wax (with maybe a bit of oil to soften it a little) would make more sense.
 
You must log in or register to reply here.
Back
Top