Knife Sharpening - Topic For May 2012
Knife Sharpening - Topic for May 2012
Hello everyone. This months topic is knife sharpening. How do you sharpen your knives? Also after you sharpen them do you test them before completing them?
I will normally take my edges down to .020 for a hunting knife and .025 for a chopper, before sharpening. I then go to the belt grinder and do a convex grind with a 220 or 320 grit J-Flex belt. I then remove the wire edge by stropping or a light buff. I will then check the edge by chopping seasoned oak or a number of other things. I also do a flex test on the edge with a brass rod to make sure the temper is correct. The knife is not completed at this stage so I can adjust temper if needed. I then go to hand rubbing the blade.
After completing the knife I like to use a Norton Tri Hone. Normally I will only use the fine india stone and it will only take a few strokes to make it really sharp. Then strop the blade to remove any wire burrs.
I also have a Norton 600 grit and 1000 grit hand stone for touch ups and sharpening things like recurves. These stones are 1/2"x 1/2"x 8".
That is pretty much my sharpening method. I am interested to see what other methods you all have.
Anvil Top Custom Knives
"How do you sharpen your knives?"
Poorly.... <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//rolleyes.gi f' class='bbc_emoticon' alt=':rolleyes:' /> This will be a good topic for me to follow.
Jeremy Lindley, Apprentice Smith
I can sharpen knives but not nearly to ABS standers.
Can't wait to see how this turns out. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' />
I pretty much follow the same method as you Brion. I take my hunters down to .015 - .020 and choppers to the same .025 before putting the convex edge on. I rough it on with a 320 j-flex belt also and then work through the finishing grits of a hand rubbed finish or mirror polish. I remove the burr with green chrome compound on a cardboard wheel. I too like to brass rod test every knife after heat treat and either cut rope or chop 2 X 4's (or both) depending on the knife's intended purpose.
For knives around the house such as my kitchen knives I usually just put what I call a convex beveled edge on them... I use the slack belt portion of my grinder (Edge down for safety) to apply the bevels. There probably isn't much of a difference between using the slack belt versus the platen to put the bevels on given the short distance from the edge to the top of the bevel, but every little thing that a person can do increases the potential of the final product... in my mind anyway.
On the knife pictured, I took the edge down to .025 before convexing it. I then tested it on a brass rod and a seasoned (85 year old) 2 X 4. I then sandblasted and painted it. After the paint was cured and the handle and guard finished, I touched the edge up on the slack belt with the finest belt that I have and then remove the burr on the hard wheel. Essentially this just made the edge "visible" for effect. (it's a Marine thing) and removed that little bit of paint to reduce drag in the cut. It's an interesting edge in that it has some very fine tooth from the sandblasting, probably similar to using a 320 or 400 grit belt. I then tested the edge's final sharpness by doing the free hanging 1" rope test and crunching through some manila rope.
This is an area of knifemaking that I've always been a stickler about. I just cringe every time I see what is an otherwise well made knife, and has huge, obtuse edge bevels. It might as well be a cold chisel!
So many folks out there view "sharp" as a totally separate thing, rather than an integrated part of the overall knife. Personally, "sharpening" starts when I begin the concept/planning of a particular knife. My goal is to have as close to a "zero" edge bevel as possible for the given blade. In order to do that, I must take into consideration the type of steel, the grind geometry, and the heat treat that will allow me to take the blade to a near zero bevel edge and still "hold up".
I use the term "cutting resistance" to describe why I choose to grind/sharpen the way I do. The less "meat" and the less bevel at the edge, the less cutting resistance a blade exhibits. In many cases a "dull" blade with low cutting resistance built into it, will actually feel sharper, and out cut a freshly sharpened blade that has the wrong geometry (such as those huge, obtuse edge bevels I mentioned earlier).
OK. All that being said, I actually have a couple of different "edges" that I will put on a knife, dependent on the given knife, and it's intended use. To explain, in my mind there are essentially two types of "sharp"...a "using" sharp, and a "collector" sharp. To obtain a "user" sharp, I will set up the edge with a worn out 400 grit belt, then finish it out on a fine India stone. This does not always produce a "hair popping" edge, but rather an aggressive, "bitey" edge. This type of edge will be more aggressive, and last longer when it comes to cutting things such as meat, hide, and other chores that most "using" knives encounter.
The "collector" edge, is what I put on most higher end pieces, that I know will rarely see hard use. I will set up the edge with a worn 400, then a worn 800, then knock the "wire edge" off with a loose buff and Pink No-Scratch compound. This produces that "scary" sharp edge, and will make arm hairs run away in fear. <img src=' http://www.americanbladesmith.com/ipboard/public/style_emoticons//smile.gi f' class='bbc_emoticon' alt=':)' /> This allows the owner to impress his/her friends by popping hairs, but that type of edge simply will not hold up well, nor last very long in "using" type situations.
Finally, one more thing that has always bugged me...so many people, who have limited knowledge of knives, are always concerned about "how hard is the steel?" Thinking that they want something super hard, so it will "hold" an edge longer. For the most part, I think we've done a very poor job as an industry when it comes to educating the public/buyers on this aspect of knives. Let's face it, any blade is going to go dull sooner or later, and require sharpening. One of the aspects that I have always tried to build into my knives is to find that "balance" between edge holding, and ease of sharpening. Which is one of the reasons that I have always had an aversion to most stainless steels....their makeup and required hardness levels, make most of them a bear for the average knife owner to re-sharpen. "Sharp" should be a part of the knife from the beginning.....not something that is considered once the knife is completed.
By the way what does this mean?
.015 - .020
is it blade thickness?
How close do you actually get to that zero edge Ed ?
Do you convex or flat bevels Ed ?
By the way what does this mean?is it blade thickness?
Yes Jonathan , that is edge thickness in thousandths of an inch.
9-11-01 , We Will Never Forget.
Work smarter NOT harder
In many cases, I try to finish grind my blades so they will have a wire edge on them when I come off a 400 grit belt. Generally I apply a combination flat grind for the majority of the blade, and convex the edge. The amount/depth of the convex will vary depending on the specific blade. For example, hunters/utility blades will have a very "short" convex, less than 1/8". Larger blades, and especially those intended for heavy use will have a deeper convex at the edge...sometime up to 3/8".
Something I discovered years ago, and that still amazes me, is how much difference that various amounts of convex at a blade's edge can make. Just having that couple of extra thousandths of "meat" at the edge (in a convex format) can increase edge strength greatly.....or a couple of thousandths too much can create too much cutting resistance. It took a lot of experimenting to figure out what I consider the "sweet spot" of having just the right amount of convex at the edge to provide less cutting resistance, yet have the strength I deem necessary.
Just a thought, since not everyone has a micrometer laying around: a credit card is about 0.030 thick - so the experienced folks here are talking about taking the edge down to 2/3 to 1/2 the thickness of a credit card before putting a convex edge on it.
Correct me if I'm wrong - I believe this style of edge is also called an "apple seed" edge.
Sorry for resurrecting this thread, but I was wondering how everyone tests for sharp? I know the standard is shaving but honestly... i dont have much hair and I am looking patchy already. Is there an equivalent? I find paper cutting is a gauge but it won't tell me if it is RAZOR sharp.
Depending on what the knife's purpose is, I might use different cutting materials. I typically will use a scrap of 6-8 oz. veg-tan leather for a hunter/skinner or general field knife. For kitchen knives, this is my test.
“So I'm lightin' out for the territory, ahead of the scared and the weak and the mean spirited, because Aunt Sally is fixin’ to adopt me and civilize me, and I can't stand it. I've been there before.”