Sharpening tools/methods???

A

adam_balisonger

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Hi people, im new to the forum and new to knives. I just got my brand new BM 42 and a SOG flash I, but I am unsure how to sharpen them. I know i want a but of a smaller angle on the BM to have it really sharp, but i have no clue as to how to acheive this. I have heard much about the Spyderco sharpmaker, but I know i defenitely want to learn how to use a stone eventually. Should I get the widely used spyderco sharpmaker? Or should i use a DMT diamond stone, or a water stone, or some other sharpening device? Somebody please help me!!
 
Read everything you can find, those links above are very good ones. Go to a hardware store and pick up a cheap black silicon carbide stone. It should be around $10 and have coarse on one side and a finer other side. If your worried about scratching up your knives then pick up a cheapy knife to learn on. That is all you need to get a knife sharp. After you do it a few times and reread everything a few more times you will be geting that cheap knife sharper than any knife you've ever had. Once you have gotten knives sharp with that stone then you can start thinking about polishing the edge for a very sharp push cutting edge and also making your edges look as good as they cut. Hint, don't start raising the angle keep the spine down close to the stone. It really does take some time to grind the edge down and produce a nice edge.
 
Using a coarse hone is the fast way to reprofile a blade to a lower edge angle, but it is easy to scratch your blade in the process. The drag on the blade with a coarse hone is high and if you aren't real used to holding the right angle you will scratch the side of your blade. It is a good idea to practice on cheap knives, particularly kitchen knives, till you get experience. I will also suggest that you start out by using a finer hone than I would use as an experience free-hand sharpener. When you are just learning it can help to put strips of tape on the sides of your blade (leaving about an eighth of an inch of steel exposed next to the edge). This can reduce scratching.

I suggest a fine or ultrafine diamond hone. These cut relatively fast, even when they are not very coarse. Here is a graph that gives you an idea of how hones rank for smoothness and speed:

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I think that Woodcraft has a sale right now on hones that would work. The fine-grit hone will cut faster and leave you with a highly effective edge, the extra-fine will give you more of a shaving edge, but takes some more time. The combination would work best, but costs almost twice as much. To set your angle you can prop one end of the hone on a block to incline the hone and hold the blade horizontally as you hone edge-forwards. With a 6-inch hone you get around 1-degree for every .1 inch you put under the end. If you put a 1-inch spacer under the end you would put about a 10-degree bevel on your edge. I would go for about 1 to 1.25 inch (10 to 12.5 degrees) for your reprofiling. To finish the edge I would free-hand at about 15 degrees per side. This give you a finished edge angle (included angle between the two bevels) of about 30 degrees. If you want better shaving I would go lower than that.

http://www.woodcraft.com/family.aspx?familyid=226
http://www.woodcraft.com/family.aspx?familyid=5909
 
Wow, that's alot of information, thanks.
I think I'll probably start off with the simple sharpmaker and then eventually work my way up to using a waterstone or a diamond stone. Basically i just want something that can give my bali a razor sharp edge.

And BTW what does reprofiling mean?
And whats a hone?
 
The "profile" of a blade is combination of grinding angles that forms the edge and the slope up to the thickest part of the blade. Certain Scandinavian blades approach an ideal wedge shape. There are single bevels on each side of the blade and they meet at the edge. It is more common for blades to initially be manufactured with single bevels on each side of the blade that don't meet at all when they come off the assembly line. They start off with a flat surface where the edge is supposed to go. A secondary grinding (aka honing) step removes some material to taper the sides down to the edge. Usually this grinding is only done in a narrow area and is at an angle steeper than the angle of the factory bevels. Most of your cutting performance comes from the angle, thickness, and precision of that final sharpening grind.

The profile of the blade consists of both the factory bevel and the sharpening bevel. You can "reprofile" the blade by reshaping either or both of those surfaces. Practically you can only shape the sharpening angle using a reasonable amount of time with hand tools. So reprofiling just means to resharpen a blade to a lower sharpening angle than when it left the factory. This is generally more work than the average person goes to. I do it using a belt sander, diamond hone, or waterstone.

If you really aren't familiar with the term, a "hone" is almost anything used to sharpen or polish a surface. It could be a rock or it could be a glass plate with diamond paste on the surface. It is a more general term than a "stone". So a bench hone could be a metal plate with diamond grit in the surface. You wouldn't call that a bench stone. You could call it a sharpener, but since you are doing all the work I would call you the "sharpener" and the hone just something that you sharpen on.
 
So when you're talking about the factory bevel and the sharpening bevel, does that mean that all knife edges steepen at 2 different angles like in the second picture, instead of just the 1 same angle coming down on either side like in the first picture?

sharpen102.jpg
 
The V-edge shown is what an ideal scandinavian grind looks like. Given the scale of your drawing a real scandinavian grind looks more like your Double Bevel edge. A typical factory edge would look like your double bevel drawing only the bottom bevel would start much higher up the sides of the image and the edge would also be further up than shown. Here is a picture of a factory blade before and after reprofiling.
 

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So is reprofiling a blade with a factory edge really neccessary? and if so, what advantages does it have?
Also, if the latter edge in that drawing represents the ideal profile of a blade, how would one go about forming that profile on a factory edge?
And if it matters at all (which I'm sure it does) the blade of my knife is made of 440c steel.
 
Lower angles, more acute angles, thinner edges cut better. Unfortunately 440C tends to break down with extremely acute angles. You may want to get AUS-8 or VG10.
 
no im not forgetting about the stones, the stones are the best way to acheive a razor sharp edge

and what about 154cm jeff?
 
I would get the Spyderco Sharpmaker first & watch the video at least twice then do just as shown and you will have a sharp blade after you get good with that get the Edge pro, pro model for your reprofiling it will take along time to do a good job . If you end up with a water stone keep it flat by rubbing it on your cement steps or any flat cement with sand between them.
 
The sharpmaker will be OK for touch-ups and basic sharpening but if you want a smaller angle on the blades then you will want something that will take off metal faster.
A belt sander will do this, however learning the physical skills to get it right without ruining a blade can take a while.
Any of the guided systems, DMT Aligner, Lansky, or the high end Edge Pro will take a bit longer than a sander to do the work but the angles are held constant for you.
In the end it depends on how much time you have and whether you are 'good with your hands' which one will be most satisfactory.
Greg
 
154CM is also not an ideal alloy for extremely low honing angles. (By extreme I am talking about final microbevels at the apex of under 10 degrees). Most people don't notice differences between some of these alloys since they don't try and thin an edge to work like a straight razor. Try one of Kershaw's newly manufactured knives with the 13C26 alloy blade or something with AUS-8 or VG10. You can reprofile these to be extremely fine and it is easier to do than on 440C.
http://www.bladeforums.com/forums/showthread.php?t=487060&highlight=13C26
 
Makers and manufacturers of quality cutlery do quite a bit of research on sharpening angles. The angles recommended are good compromises for most people. Many here feel that edges have to be "hot-rodded" to be sharp, and take sharpening to a ridiculous level.
For many, many years people who used knives learned to sharpen them with a stone.
Get an India stone, hold the edge at a 15-20 degree angle to the stone, and abrade the edge evenly on both sides. It's a very simple process that gets overengineered to death here.
 
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