Sharpening Why won't my edge sharpen?
Posted 04 November 2011 - 04:30 PM
I just got my first knife up to the point where I was ready to sharpen it. It is 1084 bought from Aldo. It was normalized after forging. I did the oil quench in ATF and the file skated off of it. I tempered it to a nice light hay color. Everything "appeared" to work great. But, I can't get an edge on that thing to save my life. Looking for some help here. I thought maybe I missed something in the process so I re-quenched twice. I then re-tempered to a hay color again in my toaster oven. Tried to sharpen, no-go. I have tried sharpening with a stone and with sandpaper up to 500 grit.
I am a newbie, so I am sure I am doing something wrong, just need some direction. I even looked at the edge under magnification and it looks good from there. The angle on both sides looks very even and it looks like it comes to a nice clean edge, but it is definitly not sharp when I feel it or try to cut anything with it. It is very discouraging.
Posted 04 November 2011 - 04:56 PM
If the blade hardened to where a file skated on it then the H/T worked. I use Aldo's 1084 and temper it twice for two hours at 435 degrees. I am at a loss to tell you what isn't working unless it is in the sharpening of the blade. Are you confident that the sharpening of it is the same as what you have had success with in the past? Let us know more of what you are doing and maybe we can be of further assistance.
Posted 04 November 2011 - 07:31 PM
As I said, this is my first knife (forged), so the only successful experience in the past would have been with kitchen knives and the knives I used when I worked at a meat processing plant. Not sure what else to tell you that I am doing. I am attempting to sharpen the knife the same way I have done regular knives in the past. I have tried different angles. I think the last angle was probably around 20 degrees or so.
A grey one. It is actually the one I used when I worked at a meat processor years ago. It is 2 sided. One side course, the other fine. I tried just the stone by itself and then I tried sandpaper after the stone, then I tried sandpaper by itself. I also have a ceramic rod style hone along with a metal hone (also from my meat cutting days), but I did not really mess with using those as the knife was not doing what I was expecting coming off of the stone. The fine side of the stone will usually get a knife to what at least "feels" like a sharp edge. I am not getting that at all here.
Number of downloads: 19
I'm sure I must have done something wrong, just not sure what.
Posted 04 November 2011 - 08:16 PM
Let us know.
Anvil Top Custom Knives
Posted 04 November 2011 - 08:26 PM
Posted 05 November 2011 - 08:47 AM
I think you guys might very well be on the issue. I don't have all that fancy equipment so removing stock takes me a great deal of time. I want to make sure that I am going to stick with it before I invest a lot more money than I already have into a $2000+ belt sander. So, right now it is files, a wheel grinder and a Harbor Freight 1x30 belt sander that I think I got for about $30 with a coupon. After watching some of the videos and seeing how fast those nice belt sanders take off stock, and after removing the drool from my mouth, I was tempted to just bite the bullet and get at least a Grizzly (just under $600 delivered with the 10" wheel) to get going...but I must be patient. I want the KMG.
My edge is pretty thick right now. The knife is about 1 1/4 inch wide at the widest point. As I bevel for the edge, I see in one book (David Boye) that he generally grinds the blade to about .03 thick at 1/4 inch from the edge before sharpening. Does this sound about right, in general. I know it really bepends on the design and all that, but I am just looking for a rough idea to get my feet wet here. I know right now my knife is way thicker than that at 1/4 inch up.
So, for now I guess I will head back to the grinder and put in some work. Thanks everyone!
Posted 05 November 2011 - 10:16 AM
You should have heard a comment someone named Fisk made about one of my first cutting knives, way too thick at the edge and it showed. It just comes with experience. You are welcome Jeff.
Anvil Top Custom Knives
Posted 06 November 2011 - 08:01 AM
This is my thought as well. In trouble shooting edges things can be broken down into two areas (that is, on something as simple as 1084), achieving an edge and holding an edge. Holding an edge is in the heat treatment, but achieving an edge is most often in the geometry. Anything that can abrade down coherently to a micron or less can be sharpened, regardless of how soft it is as long as it can stand straight; yes, some materials are ornery to the idea due to carbide size and consistency issues but 1084 isn't one of them. Skating a file is but a first step in indicating that your heat treatment is good, but it is still just a small enough glimpse of a very large picture to be quite misleading at times, but once again, in this case I don't think we need to worry about it.
Instead a look at the geometry is in order. As has been mentioned many makers go through a phase where they struggle to sharpen, it sometimes follows a phase where the sharpening was easy but edges ribboned in heat treatment . While one can leave the edge as thick as a dime for the heat treatment, that edge has to be rolled on and reduced afterwards in order to easily reach a high level of sharpness. Heavy secondary bevels are the stuff of factory made blades, not so much hand forged knives where we have the option of a better edge geometries. Those shoulders at the top of a heavy secondary bevel are the limiting factors on sharpenability and will get in the way of it by setting whatever angle they were cut at as THE angle the blade will have to be sharpened at until they are gone. By rolling on the edge and blending in your sharpening bevel, you open up the field to any number of angles you wish. In this sense factory made knives almost need those hokey sharpening guides that they sell, while a handmade knife can be sharpened by hand with much less trouble. Sort of makes sense when you see the correlation, edge bevels made by a machine with fixtures requires a fixture to resharpen, blade made by hand only require your hands to resharpen.
To fix your issue I would suggest dropping your angles when rolling the edge on the belt, and continue working it until you see the silver line of a foil edge form on each pass before moving to a stone. This will assure you have reached and edge you can work with. On the stone you should find that just about any angle the same as or higher than the one you used on the belt will quickly give you a very keen edge. Now the next step is to see how long you can keep that edge, with the concerns of all that belt work added to any heat treating concerns. This is why I use all wet techniques for sharpening level operations, but for your situation I would just worry about getting that edge for now and wait to add more worries to your plate.
Posted 06 November 2011 - 10:07 AM
You have some really good information here about edge geometry. This is likely a large part of your issue and something that you need to consider.
I asked about the stone that you are using because the type of stone and the condition of the stone can also affect the amount of effort required to get an edge sharpened. A sharpening stone can actually become dull. Any stone stays sharp by having its surface worn away exposing new sharp abrasive. Too, a stone can become loaded with metal from use and plug the spaces between the abrasive particles. The point that I am trying to make is that you need to understand that your stone is a tool, and like any tool, if it is not in top condition, it will not do its job properly. I suggest that you purchase a new stone and try sharpening your blade with it.
My main stones are Spyderco ceramic stones. I also have some DMT diamond stones that I occasionally use. The India stones that Brion mentioned are also good for starting the sharpening process. Here's a link to a company that has some pretty good basic information on stones and sharpening techniques.
Posted 06 November 2011 - 02:15 PM
Steve, Spyderco was definitly one on my radar as I noted the brand you used at the Midwest Symposium. I definitly need to invest in stones (among MANY other things), but I figured for a start, what I have on hand should get me at least close. After all, not that I am even close to being that talented or experienced at sharpebing, but if Murray Carter can get an edge on a cinder block and cardboard, I should at least be able to get one on a stone made for sharpening knives. Thanks for the link. I have saved it to my favorites for a future purchase.