Putting the final edge on

I used to use a belt sander with 220 or 320 grit belts followed by leather power stropping, and recommended it frequently. On and off over the years I got odd behavior from various blades. I finally traced it to power sharpening. After seeing the loss of performance on a few knives, I can no longer recommend it as a good way to sharpen. The knives I'm talking about were rather large, showed no color on the blades, no heat to the fingers, yet dulled quickly and dented on small branches. This was on a wide range of steels from 1055 to A2, and once on M2 that I'm not quite sure about. When I used the sander to thin the edge, but didn't let it get right to the edge, then finished by hand sharpening, I found the same 1055 and 1095 blades would cut all afternoon and still shave my arm, and make it through a couple of 2x4's or a pressure treated 4x4 without noticeable dulling. I mention these 2 steels in particular as they're the most susceptible to heat. The study mentioned was further expanded upon by later testing and found a loss of 5 points of hardness, maybe more. I don't remember the alloy, but it wasn't a plain carbon (10xx) steel.
 
Just ordered the diamond KME system and base with additional extra coarse stone. Should be here Thursday!
 
tradhunter said:
Nathan, so even your chiller platen couldn't keep the temps low enough for you?
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For this, no. The chiller keeps the platen cool, which is an issue when grinding on a radius platen or grinding lengthwise with the top wheel removed and for some folks who do regular flat grinding at high speeds and pressure, but platen heat is not an issue when sharpening. While a platen chilled with ice water can reduce the need to lift in some conditions it is not the same as grinding wet.
 
This has been a very informative thread.

Im working towards doing my secondary bevels entirely by hand but I still have issues with consistency.

My current setup is this- on the rotary platen and at loe speeds
I use a sopping wet 120 grit belt to apply the initial bevel. Then a finish the bevel with a 320-600 grit J flex belt wet. Finally i hand strop on leather loaded with green compound. This allows me to make a consistent bevel and Ive found that a coarse edge actually cuts significantly better a 1000+ grit edge.


As for the heat debate, i used to finish off all my edges on the paper wheels. I now firmly believe that they harm the temper of the edge and they also have the effect of "smoothing out" the edge and causing the knife to cut less aggressively.
 
thanks for this discussion. I saw Roman's talk at Ashokan, like a lot of people I assume. It struck me as meaningful. I don't always change my methods because of it (when I make a hunting knife for a friend who will be so shocked by a real heat treatment compared to the things he was using). But, I do take this into account when I make something to sell on the custom market. After all, people are expecting we will do the best we know how to do. If you know something can make you better, and you are selling your work to people, it seems like you should try it.

But... that's just me. I don't think anyone else should necessarily do anything like I do it.

I mostly just want to thank you guys, all of you, for taking the time to put your opinions and information out there.

take care,
kc
 
The major manufacturers use a belt, or at least the ones I've read about.

Any thoughts on the belts width?

I use a 1" belt and I'm very happy with the results, but as I mentioned, I'm also likely to finish with stones and a strop. Seems like the 2" belts would be more likely to create heat if the time spent using is the same as the more narrow belt. Even with the 1" I'm pretty quick.
 
Should this discussion extend to paper or cardboard wheels? I've often wondered how the high speed and friction of these wheels affects the HRC of knife edges.

What say you?

Fred
 
Fred.Rowe said:
Should this discussion extend to paper or cardboard wheels? I've often wondered how the high speed and friction of these wheels affects the HRC of knife edges.

What say you?

Fred
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One only needs to talk to any of the dozens (hundreds?) of customers that have sought Richard J or OHALLUM's sharpening services to dispute any claim that the paper wheels might cause any damage to a knife's edge.

I'm not saying that you are making any claims mind you, I've wondered the same, but there's a lot of evidence that the method is sound.
 
Strigamort said:
One only needs to talk to any of the dozens (hundreds?) of customers that have sought Richard J or OHALLUM's sharpening services to dispute any claim that the paper wheels might cause any damage to a knife's edge.

I'm not saying that you are making any claims mind you, I've wondered the same, but there's a lot of evidence that the method is sound.
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No claim here; just asking the obvious. I think working with the paper wheels can cause damage to an edge with enough pressure applied and a fast enough rpm. I think it depends on the operator like in most operations. I've been to Richard J's house and discussed sharpening with him. :)

Fred
 
Ah, then you know more than I. :)

I've spoken with him a few times, but haven't had a knife with one of his edges applied. OHALLUM did grace me with a treasured knife (a slipjoint) and he had sharpened it to an impressive level, but honestly, I haven't used it much.
 
There are so many variables involved that it's nearly impossible to truly put one sharpening technique against another and come to any meaningful conclusions. To do that would require a great deal of time and expense. In the long run... seriously now... who really cares about all this academia and theory?

Well, I do, and clearly many other makers and clients care, too. But there comes a point where we're "splitting hairs" just for the sake of splitting hairs...

If the edge sucks and/or doesn't last, there's a problem. If the edge cuts well and keeps cutting for a long time, there's no problem.
 
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I don't know if this is right or wrong but I have a Gatco sharpening system (similar to a Lansky setup) that I've always used. I also have a fine and very fine diamond sharpeners I try to polish the edge with but I always feel like I don't keep a consistent angle. I'm toying with the idea of using Freds bubble jig on a Coticule stone I have for polishing.
 
The paper wheels do use a wax as a lubricant/coolant from the descriptions I've seen.
 
It comes down to friction and heat build up at the apex. The apex is the thinnest cross section and will heat up fastest. What ever is being used to remove the material you have to measure heat caused by friction and fracture along the edge. There are a lot of ways to sharpen, but you have to take the time to learn how to use one tool or the other. Moving belts aren't bad, its how they are used; be alert to friction/heat buildup. Paper wheels aren't bad; pay attention to friction/heat buildup. I've seen people burn edges up with both of these techniques; I've seen some great edges sculpted on them as well. Most things these days seem to be either or; but I don't think this is one of them.

Fred
 
Fred.Rowe said:
It comes down to friction and heat build up at the apex. The apex is the thinnest cross section and will heat up fastest. What ever is being used to remove the material you have to measure heat caused by friction and fracture along the edge. There are a lot of ways to sharpen, but you have to take the time to learn how to use one tool or the other. Moving belts aren't bad, its how they are used; be alert to friction/heat buildup. Paper wheels aren't bad; pay attention to friction/heat buildup. I've seen people burn edges up with both of these techniques; I've seen some great edges sculpted on them as well. Most things these days seem to be either or; but I don't think this is one of them.

Fred
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Exactly. It has to be done correctly.

The same goes for many things in knifemaking such as forging a blade vs grinding one. If you look at the two forging has many more pitfalls while making the knife. So instead of just giving up and abandoning the method the maker takes precaution to make a forged blade.

Learning to do the craft correctly is what actually makes one a craftsman.
 
Used the KME DIAMOND set to put the edge on.
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Shaved hair from my arm so I'm happy with it. Took forever though. My fault, however, as I think I left the edge too thick finish grinding. I'm stoked.
 
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Good job Maelstrom. You live and learn, and now you know to go thinner pre-edge. The KME is a solid little system and as you can see, it's pretty easy to pull off nice, sharp edges with it right away. As long as you work both sides of the knife evenly, you're golden. If you haven't figured it out yet, you can flip the guide that holds the pivot ball up-side down and re-install for more acute angles. Also, the strop and cbn emulsion is a great addition if you don't already have it.
 
Thanks Mr. Buttry. I didn't know about the guide flip trick and the strop and emulsion is on my list for sure. The hard work is on the coarse stone so why not added a couple easy refining steps and get a nicer edge.

Thanks!
 
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