Freehanding flaw - anyone else have this issue?

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GingivitisKahn

Joined
Jun 8, 2010
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When I sharpen freehand, whether I'm using a diamond stone, a stone stone, sand paper, whatever, I seem to have issues getting the bit closest to the handle (circled in red below) as sharp as I'd like. The rest of the blade is pretty good but that straight bit - the bit I'd think would be the simplest to sharpen - seems to give me fits.

20110715img0302a.jpg


Anyone else have the same issue? Better yet, anyone have any words of wisdom?

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Beckerhead #42
 
Break the blade up into sections (if you aren't already). Its very difficult to hit the first stretch of edge unless you isolate it a bit. I also keep a finger tip or two from my support hand right on the spot I'm grinding.

Are you having any issues with the sheath on your BK11 dulling the edge (is this the only knife you have this problem with)?
 
If you freehand like most of us, with a heel-to-tip stroke, the portions of the edge closest to the choil/ricasso will get much less 'on stone' exposure. The edge closest to the inside edge of the stone comes off the stone almost immediately in the stroke. The portions of the edge nearer to the tip will get full contact across the full width of the stone, assuming a heel-to-tip stroke down and across the stone. For that reason alone, it'll take longer to remove the same amount of steel from portions nearer to the ricasso.

A lot of blade grinds are also somewhat thicker near the heel. If the edge bevel from the maker is uniform in width (width measured from edge to the shoulder of the bevel), the edge will almost always be more obtuse (thicker) nearer to the ricasso. That is another major factor in why it takes longer to sharpen it. More of the blade's thickness must be removed there, so it'll take longer, and it will also widen the bevel there, if the same edge angle is maintained for the entire edge.

Yet another factor. Most blades are shaped & ground on belts. Close to the ricasso, the 'plunge line' (edge of the grind that separates the actual blade from the ricasso & tang), will usually be curved in a concave shape. If looking at the edge straight on (blade laying flat in front of you, edge toward your eyes), imagine laying a flat hone flush against the edge. As the hone is moved closer to the heel, the edge of the hone will 'ride up' that curved portion of the plunge, and most of the stone's surface will be lifted away from the edge, leaving only the outer edge of the stone in contact. This means every time the stone gets close to the heel, it'll be lifted off the edge. This can be compensated for, somewhat, by using a stroke that moves from tip-to-heel, instead of the other way. But it will still take longer.
 
HeavyHanded said:
Break the blade up into sections (if you aren't already). Its very difficult to hit the first stretch of edge unless you isolate it a bit. I also keep a finger tip or two from my support hand right on the spot I'm grinding.

Are you having any issues with the sheath on your BK11 dulling the edge (is this the only knife you have this problem with)?
Click to expand...

Not just that knife but knives in general.

So you're suggesting I should concentrate on the problem area and once that's sharp, concentrate on the rest of the blade to even things out (as opposed to trying to sharpen the entire edge in one stroke)?

Obsessed with Edges said:
If you freehand like most of us, with a heel-to-tip stroke, the portions of the edge closest to the choil/ricasso will get much less 'on stone' exposure. The edge closest to the inside edge of the stone comes off the stone almost immediately in the stroke. The portions of the edge nearer to the tip will get full contact across the full width of the stone, assuming a heel-to-tip stroke down and across the stone. For that reason alone, it'll take longer to remove the same amount of steel from portions nearer to the ricasso.

A lot of blade grinds are also somewhat thicker near the heel. If the edge bevel from the maker is uniform in width (width measured from edge to the shoulder of the bevel), the edge will almost always be more obtuse (thicker) nearer to the ricasso. That is another major factor in why it takes longer to sharpen it. More of the blade's thickness must be removed there, so it'll take longer, and it will also widen the bevel there, if the same edge angle is maintained for the entire edge.

Yet another factor. Most blades are shaped & ground on belts. Close to the ricasso, the 'plunge line' (edge of the grind that separates the actual blade from the ricasso & tang), will usually be curved in a concave shape. If looking at the edge straight on (blade laying flat in front of you, edge toward your eyes), imagine laying a flat hone flush against the edge. As the hone is moved closer to the heel, the edge of the hone will 'ride up' that curved portion of the plunge, and most of the stone's surface will be lifted away from the edge, leaving only the outer edge of the stone in contact. This means every time the stone gets close to the heel, it'll be lifted off the edge. This can be compensated for, somewhat, by using a stroke that moves from tip-to-heel, instead of the other way. But it will still take longer.
Click to expand...

Good info - thanks for that. Your first point about on stone exposure had occurred to me as well and I try to go out of my way to address that but I'm not sure how successful I've been with that.

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Beckerhead #42
 
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I understand the advice to break the edge up into sections. However, note that when you do that, at least in my limited experience doing it, it's harder to develop a consistent "burr" across the entire blade, before you flip it over. Because the general advice among the more experienced sharpeners here is NOT the Spyderco SM approach of just alternating sides of the blade with every stroke. Instead, the general advice is to keep going on one side until you've established a burr.

If that's true, then doing the blade in sections makes it tricky to get a burr, because in reality, you end up with different "burrs" all along the edge. Maybe that's not a bad thing, but it is a side effect I've noticed when I try to do my edges in sections rather than with a continuous stroke from heel to tip.
 
maximus83 said:
I understand the advice to break the edge up into sections. However, note that when you do that, at least in my limited experience doing it, it's harder to develop a consistent "burr" across the entire blade, before you flip it over. Because the general advice among the more experienced sharpeners here is NOT the Spyderco SM approach of just alternating sides of the blade with every stroke. Instead, the general advice is to keep going on one side until you've established a burr.

If that's true, then doing the blade in sections makes it tricky to get a burr, because in reality, you end up with different "burrs" all along the edge. Maybe that's not a bad thing, but it is a side effect I've noticed when I try to do my edges in sections rather than with a continuous stroke from heel to tip.
Click to expand...

I've also usually sharpened these in sections. The key is to really, really watch with every stroke, to see how the edge is developing. Use a magnifier. When it's getting very close to forming the burr, decrease pressure to very light. And maintain a somewhat abbreviated 'sweep' to the stroke in each section, so as to blend the overlap between each. With some practice, the finished edge will look 'as one'.
 
GingivitisKahn said:
Not just that knife but knives in general.

So you're suggesting I should concentrate on the problem area and once that's sharp, concentrate on the rest of the blade to even things out (as opposed to trying to sharpen the entire edge in one stroke)?
Click to expand...

Exactly. I used to do every edge with one sweeping stroke, even machetes which meant I had to manufacture 18" bench stones from SiC sanding belts. Then something happened when I was experimenting with circular sharpening using a circle about the size of a dime on the stone, working my way up and down the edge. You end up with a swirling hodge-podge of scratch patterns - very ugly. With no more than 3 or 4 heel to tip strokes I was able to completely cover the old pattern with a perfect unidirectional one. Conclusion, reducing the distance my hands travel per grinding motion reduces the amount of pitch variation = much cleaner bevels. One also doesn't have to grind the entire edge to clean up one stretch of blade - much faster and reduces unnecessary metal removal. By overlapping the areas you hit - I don't try to exactly stop and start at specific areas, rather I just work my way along the edge - you wind up with cleaner bevels and no need to whip up more of a burr in any one spot than is absolutely necessary. It might require a slight bit of adjustment, but for freehanding I highly recommend it - certainly improved my consistency. Best way for me to describe it is a linear scrubbing type of motion with the blade canted back about 30 to 40 degrees from the grind direction. I only move about 1.5 to 2 inches per stroke and move it all over the stone as I go. This keeps the wear even on a waterstone, and keeps the swarf buildup distributed more evenly on a solid stone - fewer stops to clean it off and it interferes less with clean grinding on the stone.

Then there's Obsessed's observation about the recurve portion common to so many belt sharpened knives. All of my stones are "eased off" a bit on the long corner so I can get nice and snug to the stone even if it has a bit of a recurve - I lapped 'em down to a nice soft radius. You can do it with the corner of a stone, but it beats it up - the scratch pattern looks like you're using a much rougher stone than the rest of the edge.
 
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maximus83 said:
I understand the advice to break the edge up into sections. However, note that when you do that, at least in my limited experience doing it, it's harder to develop a consistent "burr" across the entire blade, before you flip it over. Because the general advice among the more experienced sharpeners here is NOT the Spyderco SM approach of just alternating sides of the blade with every stroke. Instead, the general advice is to keep going on one side until you've established a burr.

If that's true, then doing the blade in sections makes it tricky to get a burr, because in reality, you end up with different "burrs" all along the edge. Maybe that's not a bad thing, but it is a side effect I've noticed when I try to do my edges in sections rather than with a continuous stroke from heel to tip.
Click to expand...
With a bit more practice, I suspect you'll find the opposite. Using one sweeping motion, you might raise a burr at one point, but not another. By continuing with the entire edge you wind up with all manner of burr variation as each stretch of bevel grind reaches the apex with a different number of strokes. That variation in burr size could turn into a real headache down the line. Careful observation and you only need to work on the regions that need it. I can't argue against a full sweep too much since this is how I used to do it for many years and got good results. My results using a segmented approach are better.
 
Here's a link to a thread I came across a while back, from the 'Custom & Handmade Knives' sub-forum. It sheds some light on the blade & edge geometry near the ricasso that contributes to these sharpening difficulties. If you look further down into the thread, there are some illustrations & photos of the radiused curve in the plunge, near the ricasso. Interesting perspective, mostly from the guys who make blades:

Why do some makers not sharpen the entire blade?
 
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Yes, these are some really useful and practical insights. In the last month, I think I've learned more about sharpening than I knew in an entire 40+ year lifespan!

You know, it would be SO cool to collect some of the "consensus" details about freehand sharpening that have been covered in many of these threads, and compile a "Guide to Freehand Sharpening". It would really save people a LOT of time versus hunting through dozens of old threads.
 
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