Sharpening technique for "straight" edge traditionals

[btb01]

Over the last year or so, as I've gotten more into traditional folders, I have also found myself sharpening a lot more (mostly because I like putting my own edge on a new knife). I have (at least in my admittedly amateur opinion) become adequately adept at putting a good, functional edge on my knives. For a while I was using Arkansas stones with so-so results. I've now switched to DMT Dia-Sharps and am very happy with the results. I have a Fine and an Extra Fine. The Fine seems plenty aggressive to me (especially on 1095, which is 90% of what I'm sharpening), so I don't see the need for anything coarser. Occasionally I'll finish with a Black Hard Arkansas stone after the Extra Fine, or a strop, or both, but often the two DMT's seem to get the results I want.

As I've started collecting more traditionals, I've purchased a few straight edge knives - sheepsfoot, wharncliffe, etc., mostly GEC's, a Case Swayback Gent, stuff like that. While I've often read that many people here find straight edge blades easy to sharpen, I've found the opposite to be the case. I've come to find that these "straight" edges are often not perfectly straight, and that's given me some trouble when I put them to a flat sharpening stone. I usually use a Sharpie to make sure my angle is correct, and when I do this with these not-perfectly-straight straight edges, no matter how many passes I make, the Sharpie at the tip of the blade remains. If I hold the blade at a 90° angle to a flat surface, I can see that the edge is not perfectly straight - most often it curves up ever so slightly at the tip, which I guess explains the Sharpie.

I've tried two things to remedy this. First was just keep sharpening and sharpening until the rest of the edge catches up to the tip and evens itself out. And this works… eventually. The problem is that you seem to sharpen away far too much steel doing this. I have a sheepsfoot GEC 25 that I did this with, and by the time I sharpened it enough to straighten the edge out, I had also removed enough steel that the small notch/choil between the edge and the kick was completely gone. I've also tried lifting the handle as I sharpen - like you would on a blade with belly to follow the curve - but very slightly, just to make sure the tip gets down on the stone. This seems to work ok, I guess, but it also leaves the edge with some odd-looking transitions.

So my question is this:

Has anyone else had this problem? Is there a better way to sharpen these not-quite-straight edges? Is there something I'm missing, or am I not thinking about this the right way? Any recommendations or ideas are greatly appreciated!

 

[on_the_edge]

It sounds to me like you are dealing with a "modified" wharncliffe or sheepsfoot blade where the edge is not flat along its entire length, but presents with an ever so slight belly. An example of such an edge would be the CRK Insingo, though that may have a more pronounced belly than what you are dealing with. Still, if I understand you correctly, the correct way to sharpen those knives with stones so far as I know is to use the second method you describe above. I'm not sure why the transitions look "odd" unless you are not being consistent and smooth with lifting the handle. As an alternative, maybe trying a stroke towards the edge of the stone so you are dealing with the tip close to the edge of the stone might produce a better transition. With the edge away from you, rotate your hand to push the tip of the knife forward while holding the handle back a bit, if that makes sense.

I understand what you are saying about sharpening until the rest of the edge catches up with the tip, but that would be a last resort for me personally. IMO, that is just removing way more steel than is necessary.

 

[btb01]

I know the type of "modified" straight edge that you're talking about, but that isn't what these are. On the GEC knives, I think it's likely a result of the edge being finished by hand on a belt, but I'm not sure. The amount the tip comes up off a flat surface when the edge is held at 90° is less than a millimeter, and it's only the very tip (last 1-2mm), but it's just enough to keep it from touching the stone when sharpening. You might be right about my consistency with lifting the knife as I sharpen - I've only tried this with one knife, a GEC #15 Beer Scout, so the slight adjustment needed may just take practice.

 

[Rey HRH]

If the tip lifts up, why not sharpen it as you would any knife with a belly and follow the slight curve? On a flat stone, you do have to lift up slightly on the handle as you near the belly / tip but the point is to maintain the same angle to the blade as you go around the belly as the angle you have on the straight portion.

 

[Obsessed with Edges]

Over the last year or so, as I've gotten more into traditional folders, I have also found myself sharpening a lot more (mostly because I like putting my own edge on a new knife). I have (at least in my admittedly amateur opinion) become adequately adept at putting a good, functional edge on my knives. For a while I was using Arkansas stones with so-so results. I've now switched to DMT Dia-Sharps and am very happy with the results. I have a Fine and an Extra Fine. The Fine seems plenty aggressive to me (especially on 1095, which is 90% of what I'm sharpening), so I don't see the need for anything coarser. Occasionally I'll finish with a Black Hard Arkansas stone after the Extra Fine, or a strop, or both, but often the two DMT's seem to get the results I want.

As I've started collecting more traditionals, I've purchased a few straight edge knives - sheepsfoot, wharncliffe, etc., mostly GEC's, a Case Swayback Gent, stuff like that. While I've often read that many people here find straight edge blades easy to sharpen, I've found the opposite to be the case. I've come to find that these "straight" edges are often not perfectly straight, and that's given me some trouble when I put them to a flat sharpening stone. I usually use a Sharpie to make sure my angle is correct, and when I do this with these not-perfectly-straight straight edges, no matter how many passes I make, the Sharpie at the tip of the blade remains. If I hold the blade at a 90° angle to a flat surface, I can see that the edge is not perfectly straight - most often it curves up ever so slightly at the tip, which I guess explains the Sharpie.

I've tried two things to remedy this. First was just keep sharpening and sharpening until the rest of the edge catches up to the tip and evens itself out. And this works… eventually. The problem is that you seem to sharpen away far too much steel doing this. I have a sheepsfoot GEC 25 that I did this with, and by the time I sharpened it enough to straighten the edge out, I had also removed enough steel that the small notch/choil between the edge and the kick was completely gone. I've also tried lifting the handle as I sharpen - like you would on a blade with belly to follow the curve - but very slightly, just to make sure the tip gets down on the stone. This seems to work ok, I guess, but it also leaves the edge with some odd-looking transitions.

So my question is this:

Has anyone else had this problem? Is there a better way to sharpen these not-quite-straight edges? Is there something I'm missing, or am I not thinking about this the right way? Any recommendations or ideas are greatly appreciated!

You've noticed it too.

I've yet to see a sheepsfoot or wharncliffe blade that's PERFECTLY flat & straight. Even the slightest variation in the primary grind or thickness behind the edge will translate to uneven-width bevels, especially if sharpened very THIN to low edge angles. Every 'ripple' in the primary grind will show up there. Secondly, a lot of thinner sheepsfoot blades will also be slightly bent or curved to one side or the other, as viewed tip-on or from the heel, along the edge. This means, when sharpened on one side, only the ends of the blade will make contact, and when sharpened from the other side, only the central portion contacts the flat hone. That creates even more unevenness in the bevels' width. And lastly, as you mentioned, rarely is the edge dead-straight if viewed from the side, with a little bit of 'belly' visible near the tip (usually). More obvious, if the edge is placed on the surface of a flat hone for a straight-edged reference.

I've considered using some sort of specialized means to sharpen them, in attempting to match or compensate for the irregularities in the grind. But I've decided just to sharpen them 'as is', using the same hones and means as with all my other blades. To me, it's pointless to try to make the edge look 'perfect' if the primary grind is anything but. If there's an excess of 'belly' near the tip, or if the tip is too-noticeably upswept, that can be corrected somewhat just by grinding the edge flat with the blade cutting perpendicularly to the stone's surface, then regrinding the edge bevels. OR, if the tip is rounded off, grinding the spine at the tip is one way to put a sharp point at the tip again.

With very thin sheepsfoot blades, some of the 'ripples' in the edge grind (& therefore the bevels) can be 'disguised' or blended into the primary grind by using a strop of hard-backed denim with an aggressive compound, like white rouge or other aluminum oxide polishing compound. That's how I've 'shaped' the bevels & shoulders of my sheepsfoot blades, for the most part. It leaves the bevels with a very shallow convex, and the shoulders of the 'bevels' essentially blend in or disappear, minimizing their otherwise hideous & wavy appearance if left with crisp shoulders.


David

 

[Trout Hound]

I just recently had the same problem with the sheepsfoot on a Case 6318 that was not even remotely straight. I found that sweeping the blade off the edge of my DMT plate with each stroke gave me significantly better results. By doing this, you get much more even contact with the abrasive across the entire edge, resulting in much more even bevel lines. Hope this helps.

 

[Bighaze51]

There is a trick I learned from honing straight razors that are warped. I believe it's called something like a rocking x-stroke. Instead of laying the blade flat, you actually tilt the handle down so the tip of the blade is in the air and only the heal of the blade is in contact with the stone. Also, you want the handle pointing away from you and the tip of the blade towards you. As you start the first stroke, you rock the blade on the stone. Just imagine how a rocking chair works. So as you continue through the stroke, you roll the blade from the heel to the tip. And you are only using maybe 3/4 to 1 inch of the stone towards the edge. The. You repeat it on the other side with the butt of the handle leading the stroke. I've gone warped straight razors this way and was able to get an otherwise useless razor into shave ready condition. I hope I explained this well enough. If not,'do a good lenses have for how to hone a warped straight razor. You can apply the same technique for a warped or bent pocket knife blade

 

[btb01]

Obsessed with Edges, that's exactly what I'm talking about! :thumbup: I knew I couldn't be the only one. I think you're probably right about slight variations in the primary grind being the culprit, and the thinness of the blade exacerbating the problem (which is why this happens, I'm guessing, mostly with traditionals and not modern folders). I've thought about grinding the edge down (holding the knife perpendicular to the stone) then reprofiling the edge as you say, but having not done so before, I was always afraid I'd screw it up.

Thanks for the recommendations, guys!

 

[cbwx34]

I just recently had the same problem with the sheepsfoot on a Case 6318 that was not even remotely straight. I found that sweeping the blade off the edge of my DMT plate with each stroke gave me significantly better results. By doing this, you get much more even contact with the abrasive across the entire edge, resulting in much more even bevel lines. Hope this helps.

^ This... or applying a little downward pressure with my finger at the tip seems to work for me.

 

[Obsessed with Edges]

I just recently had the same problem with the sheepsfoot on a Case 6318 that was not even remotely straight. I found that sweeping the blade off the edge of my DMT plate with each stroke gave me significantly better results. By doing this, you get much more even contact with the abrasive across the entire edge, resulting in much more even bevel lines. Hope this helps.

To some extent, this happens more or less by default on warped/bent/curved blades anyway. Sharpening from one side of the blade, the heel & tip will already be in contact near the edges of the stone, and the remainder of the edge will sweep across the near edge of the stone as the blade comes off it. And sharpening from the other side, only the tip OR heel can be in contact at any one moment (depending if the handle is lifted for the tip, or lowered for the heel), and the whole of the edge will still sweep across the edge of the stone again, as it comes off the stone during the stroke.

To make it a little less hazardous for the blade on the edge of the stone (which focuses pressure laterally against the blade's edge, increasing risk of rolling/chipping), rounding off or chamfering the stone's edge can help distribute the pressure as the blade's edge sweeps off the stone.


David

 

[bgentry]

OWE covered it fairly well. You've got some choices:

1. Radically flatten the edge by cutting directly into the stone and shape the blade until it's as straight as you want it. Then cut brand new bevels into it, making a "perfect edge". Of course you'll remove a good bit of steel in the process.
2. Treat the imperfection at the tip sort of like a chip: Keep sharpening normally and eventually, you'll grind away enough of the straight part of the edge to reach the tip. But in the mean time, the tip won't be any sharper.
3. Treat this just like any other knife and follow the (very slight) curve near the tip. Use Secret #3 to do so. Be sure to employ secrets #1 and #2 as well.

Brian.

 

[Trout Hound]

Yes, I was careful, with my method, to keep pressure very light on the edge of the stone, to prevent other problems. I just bought a second Crystolon stone, and my plan is to round over one edge on each side so that I'll have it in my arsenal for recurves, as well as for these situations.

 

[cbwx34]

I've thought about grinding the edge down (holding the knife perpendicular to the stone) then reprofiling the edge as you say, but having not done so before, I was always afraid I'd screw it up.

I wouldn't recommend this for a few reasons: First, it's a waste of steel... there's very little benefit to be gained other than looks. Second, the tip, in most cases, sees more action than the rest of the blade, so it dulls and wears faster, which leads to the third reason, tips are often sharpened more than the rest of the blade, so even if you ground it flat, in a few months of use/sharpening, you'd be back to where you were. (It's often also easier to over sharpen the tip area depending on the blade, since it's often thinner and easier to apply too much pressure to, and/or remove too much metal in this area).

Isolating the tip and sharpening it just enough to keep it cutting, IMO, will provide better results long term. I also wouldn't recommend pretending that it's like any other knife and "follow the curve to the tip"... that will only exaggerate the issue. I try and keep everything as straight as possible, and do just enough to the tip to keep it cutting.

I'd also suggest that you check a new knife and see if the knife comes the way you describe, or if it's something you're doing when you start sharpening... it's easy to fall into the habit of slightly lifting the handle (or whatever you use on a regular knife) to sharpen the tip, and you may unconsciously be introducing it into your flat edges. Just a possibility to consider.

 

[Obsessed with Edges]

Yes, I was careful, with my method, to keep pressure very light on the edge of the stone, to prevent other problems. I just bought a second Crystolon stone, and my plan is to round over one edge on each side so that I'll have it in my arsenal for recurves, as well as for these situations.

Perfect.

I was actually thinking of a SiC stone when mentioning that; one of mine has chamfered edges for the same reason. They're very easy to reshape as needed, and they're a good 'fit' otherwise, for traditional knives in general. The two go well together.


David

 

[Kcsstrat]

I just recently had the same problem with the sheepsfoot on a Case 6318 that was not even remotely straight. I found that sweeping the blade off the edge of my DMT plate with each stroke gave me significantly better results. By doing this, you get much more even contact with the abrasive across the entire edge, resulting in much more even bevel lines. Hope this helps.

May I ask what exactly you mean by "sweeping" the blade?