Sharpmaker Flats?

R

Robert Ptacek

Joined
Oct 8, 2013
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308
Does anyone just use the flats to sharpen plain edge blades exclusively?Or are the corners required to set edge after a reprofiling.
 
I use the flats. As Sal explained it the corners are faster though since the smaller surface = higher point load and more metal removed with each stroke.
 
From the threads I've read about the Sharpmaker most people seem to use just the flats for the entire process. The corners load fast and too much pressure can deform the edge.
 
I almost exclusively use the flats but I do find the corners work a little better on a recurve blade. At least for me.
 
I only use the corners, it seems no matter how much I focus on holding it to the stone with the flats only about the same surface area as the corners makes contact with the edge at any given time anyhow, corners seem work better to hit the entire edge ime, also I don't think the mediums are very aggressive even clean I do want to get the more coarse stones though
 
From reading a lot of SM posts once upon a time, I got the idea that "flats only" was the way to go. Recently, though, I've been using the corners again when I need something a little more aggressive than just the flats. The caveat is that it's hard to finesse the very tip with the corners, so when I use the flats at the next step, I give extra attention to the tip.

I guess I'd forgotten how much the corners can simplify the work. For instance, my wife uses her kitchen knives a lot and I try to tune them up for her every week or two. Using just the flats, I would sometimes get frustrated with how long it took. But just a short session with the corners, followed by another short session on the flats, does the trick.

Another good use for the corners is the heel area next to the tang. That part is often incompletely ground from the factory and needs some work. I set my initial bevels with a Work Sharp KO but often can't completely sharpen that area without adding an unwanted "recurve". So I'll stop short and go to my SM. The corners allow you to focus in on just that very small area and bring it to apex.

Andrew
 
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aleforme said:
I almost exclusively use the flats but I do find the corners work a little better on a recurve blade. At least for me.
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I actually use the flats for recurves, but I use my sharpmaker stones sort of weirdly, in that i hold the knife in one hand and the stone in the other. Using the flats on a recurve is actually like using 2 corners on the recurve at the same time. The recurve arcs over the flat and contacts the two corners which sweep the recurve one after another.

As I do double freehand it is very hard for me to feel when the edge lays flat on he sharpmaker rod on the single corner.
 
Just trying to pick other peoples brains for different techniques.Thank you for the feedback and keep them coming.
 
Robert Ptacek said:
Does anyone just use the flats to sharpen plain edge blades exclusively?Or are the corners required to set edge after a reprofiling.
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If I'm reading your question correctly, and the edge is already reprofiled, then the edge should already be set, in terms of reaching a full apex at the desired geometry. If so, most any work that follows should be relatively light anyway; just refining, in other words. Done with a good, light touch, it shouldn't matter then, which part of the rods (corners or flats) you use. Use it according to your preference, in that case.

If you're asking if the corners should be used to do the reprofiling (setting the edge), I personally don't like using them at all, for that. As mentioned earlier, and taking into account the assertion that the corners focus and increase pressure (presumably to cut deeper and remove more metal per pass), the corners of the ceramic rods load up with swarf very quickly, sometimes in just a handful of passes, and more so with focused pressure. When they get loaded up, they slow down dramatically in their ability to remove metal. And additionally, the focused pressure is more likely to roll or chip the edge as it gets thinner.

The Sharpmaker, with the standard ceramic rods alone, isn't a very good reprofiling tool. If you have the diamond or cbn rods for it, they'd be more effective for that. Even then, for myself, I'd still be inclined to just use the flats for most of the grinding work, as there's more abrasive surface area to work on the steel and therefore a lesser tendency to get loaded up and clogged very quickly; and the larger, flatter abrasive surface area is less likely to focus lateral pressure on narrow segments of the edge to damaging levels. Reprofiling is a task that most of us intuitively want to do with increased pressure, to 'hog off' metal quickly. Trying to use heavier pressure on the corners of the rods is a bad combination, for the sake of the edge.

For any light work that won't generate a lot of swarf to clog the abrasive, the corners can work fine. Just be sure to keep the pressure featherlight, when using them. And even if you're not generating a lot of swarf, it's still a good idea to wipe down the corners of the rods fairly frequently, to keep them cutting effectively. Use an eraser, or something like a microfiber towel with some Windex for that (that's how I do it, most of the time). If you notice any burring while doing so, or worse, chipping in steels at higher hardness, that's the strongest indicator the pressure is heavier than it ought to be.

Edited to add:
(If this helps at all...) Sometimes, when I feel my own 'touch' with applied pressure isn't quite on the mark and a bit unsteady or too heavy, I'll be more inclined to use the flats only, to minimize complications with burring or edge-rolling. On other days, when I'm more 'in the zone' with my light touch, I find using the corners can work very well for the very last, finishing touches. Sort of similar to using a kitchen steel on an edge, in that regard. But I still will never use the corners for any heavy work, at all.
 
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AFAustin said:
Another good use for the corners is the heel area next to the tang. That part is often incompletely ground from the factory and needs some work. I set my initial bevels with a Work Sharp KO but often can't completely sharpen that area without adding an unwanted "recurve". So I'll stop short and go to my SM. The corners allow you to focus in on just that very small area and bring it to apex.
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Andrew,
That is really good info !
THANK YOU !
 
What I was wondering if the corners do a better job of cleaning up the edge that is burred after a reprofiling than the flats seeing it is more aggressive?
 
Robert Ptacek said:
What I was wondering if the corners do a better job of cleaning up the edge that is burred after a reprofiling than the flats seeing it is more aggressive?
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More aggressiveness isn't necessarily a good thing for cleaning up burrs. A lighter & more delicate touch is best for that; a more aggressive approach might actually make burring worse, working the edge against the hard, narrow corners of the rods. If your touch is very good, there'll come a point when you can use whatever works best for you. But the flats of the rods will help distribute pressure instead of focusing it, which effectively lightens it. For burr cleanup, I'd favor the flats for that.


David
 
AFAustin said:
... Another good use for the corners is the heel area next to the tang (Italics mine). That part is often incompletely ground from the factory and needs some work. I set my initial bevels with a Work Sharp KO but often can't completely sharpen that area without adding an unwanted "recurve". So I'll stop short and go to my SM. The corners allow you to focus in on just that very small area and bring it to apex.
Andrew
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This is one of my main uses for the corners, also. My WE doesn't get all the way back to the beginning of the blade choil on my PM 2's and PM 3 because the diamond plate on the sharpening blocks doesn't go all the way to the edge of the block. I can get the last little bit with a corner of the SM rods or with a hand held sharpener like a DMT Dia-Fold.
 
Hey guys,I appreciate all your input.Sometimes I need to break away from my rigid thinking and explore new techniques.I wish all of you a Merry and Blessed Christmas.
 
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