Q: Is there an in between process for knives that have a decent edge?

[bdaabat]

Quick question: what do you all do for knives that have a decent edge that you just want to touch up to get back to their full potential? Meaning, do you start with a relatively aggressive abrasive (I'm using a belt system, so my usual starting belt is a P120 grit belt) to definitively raise a burr? Or, do you start with something more fine and try to save some metal in the process?

Thanks!
Bruce

 

[Blues]

I generally either strop...with or without diamond emulsion... or give it a few swipes on ceramic . If I need more than that, I'll go to a diamond hone of appropriate grit.

I don't have any mechanized sharpening tools / belts.

 

[Obsessed with Edges]

For me, a lot depends on the specific character of the edge's sharpness. In other words, if it's got good edge geometry and a certain toothy slicing aggression that I prefer, I try to minimize how much it gets altered in touching it up. That usually means I'll just give the edge a few very light passes on a medium or fine ceramic hone to apply the most minimal of micro bevels.

Until recently, almost all knives that were new to me would get reprofiled to my preference, whether the original edge was 'decent' or not. I always prefer narrower edge geometry than most makers will set by default. But over the last couple or three years, I've finally found one manufacturer's factory edges to be very, very good. I've not felt compelled to alter them straight out of the box, but instead do as I described above, just lightly enhancing them with a ceramic hone.

I've come to really like an edge that's initially set with a relatively coarse hone, like a Coarse or maybe even an Extra Coarse DMT (325 and 220 grit, respectively), and then micro beveled with a medium ceramic. That makes for a wickedly aggressive slicer that's also very durable over time. Eventually, after the ceramic has taken much of that coarse bite out of the edge, that's when I'd be inclined to completely reset it to my liking with the C/XC hone again.

As for raising a burr, I don't deliberately aim for that every time I touch up an edge. Instead, I'll just test cutting performance as I go, slicing some fine paper like phone book pages or catalog pages, or paper towels, to see if the edge cuts like it's already fully apexed and burr-free. Paper towels are a very good way to test an edge for the presence of burrs in particular.

 

[Maximumbob54]

I quit thinking I have to use each stone or plate in the kit. I started years ago with the standard Lansky four stone system and I would go coarse to fine thinking that's how it was done. These days now that I'm finally long since done grinding all the blades away I just generally use whatever mediumish type to touch up an edge and I've been happy ever since. Long winded way of saying it's less about in between than just generally one and done.

 

[conan11]

Well before my blade goes dull a few light strokes on ceramic seems to get it back slicing very nice. If it needs a little more a few passes on fine Diamond . If sort of dull start back on course diamond. I try to remove the bur with very light strokes.

 

[annr]

If the blade has not reached the point of “too thick behind the edge”’or a straight edge is no longer straight, I work in reverse: steel, ceramic honing rods, (#1000), #600 grit, etc. This is quickest most reliable IME and spares the steel.

If you start back at square one, you can wind up with deep scratch marks needing removal or create additional problems.

 

[bdaabat]

Thanks all. In the time after posting this and checking my daily use knives, I decided to try a little test. Three different knives with different metals. All had been previously re-profiled to the same edge angle. They were not in exactly equal condition. One knife just needed to be re-sharpened. The other two got just several passes with the Edge Pro super fine micromesh belt (10,000 grit) on the Work Sharp KOMk2.

Results were decent for one knife (Mercer) and no discernible change for the other (Victorinox). I don't have formal testing tools. I was using magazine paper to test.

Ended up fully sharpening (meaning, starting a P120 grit, then Trizact 600, then felt belt with 3 micron diamond emulsion then leather belt with 1 micron diamond emulsion) all of them anyway since I was already there and doing the other knife.

What does this mean for me moving forward?
For me, I think it means I need to just keep testing.

Was the micromesh belt the "right" belt for this test? Donno. I'll continue testing using more coarse belts and see what happens. This was just one test.

But, the bigger takeaway is that there are too many variables to be able to make a lot of generalizations. Different metals, different blade thicknesses, different starting conditions for each knife, etc. Bottom line: the goal is still the same: get a sharp edge. If that means starting coarse for a particular knife, so be it. If I can try using a more fine grit and it works for that knife, great!

I only started going buck willy with sharpening last summer. I've learned a lot since then. I've sharpened several hundred different knives between then and now. The main thing I've learned is that there is a HUGE amount left to learn!

Bruce

 

[annr]

For me, a lot depends on the specific character of the edge's sharpness. In other words, if it's got good edge geometry and a certain toothy slicing aggression that I prefer, I try to minimize how much it gets altered in touching it up. That usually means I'll just give the edge a few very light passes on a medium or fine ceramic hone to apply the most minimal of micro bevels.

Until recently, almost all knives that were new to me would get reprofiled to my preference, whether the original edge was 'decent' or not. I always prefer narrower edge geometry than most makers will set by default. But over the last couple or three years, I've finally found one manufacturer's factory edges to be very, very good. I've not felt compelled to alter them straight out of the box, but instead do as I described above, just lightly enhancing them with a ceramic hone.

I've come to really like an edge that's initially set with a relatively coarse hone, like a Coarse or maybe even an Extra Course DMT (325 and 220 grit, respectively), and then micro beveled with a medium ceramic. That makes for a wickedly aggressive slicer that's also very durable over time. Eventually, after the ceramic has taken much of that coarse bite out of the edge, that's when I'd be inclined to completely reset it to my liking with the C/XC hone again.

As for raising a burr, I don't deliberately aim for that every time I touch up an edge. Instead, I'll just test cutting performance as I go, slicing some fine paper like phone book pages or catalog pages, or paper towels, to see if the edge cuts like it's already fully apexed and burr-free. Paper towels are a very good way to test an edge for the presence of burrs in particular.

One caveat I would add: the steel can be a limiting factor.

I tried using diamond (#320, max) on 440-C, 59-60HRC, and I wound up tearing out/chipping some of the edge (very thick single bevel) in a couple of spots. This was a fairly expensive knife by a good maker. I don’t know if I should have known better or there was something wrong with the steel. I was not expecting this.

 

[FortyTwoBlades]

As others have mentioned it all comes down to the specific condition of the edge, the desired edge condition, the equipment available to me in the moment, and also the nature of the steel and heat treatment. Some steels bounce back nicely with nothing more than a simple light scrub on both sides on a sintered ceramic plate. Others benefit from resetting the scratch pattern on a coarse or medium stone and then progressing to a fine bonded abrasive, and so on and so forth. Ultimately, you need to learn your knife's behaviors and how it best performs for your contexts of use.

 

[Obsessed with Edges]

One caveat I would add: the steel can be a limiting factor.

I tried using diamond (#320, max) on 440-C, 59-60HRC, and I wound up tearing out/chipping some of the edge (very thick single bevel) in a couple of spots. This was a fairly expensive knife by a good maker. I don’t know if I should have known better or there was something wrong with the steel. I was not expecting this.

I had one knife, a Kershaw Leek in ZDP-189, that made me rethink my use of a diamond hone when I reprofiled it. ZDP-189 is commonly hardened very high, into the mid-60s HRC. But it's much more brittle at such hardness. I'd reprofiled the edge to narrower geometry than factory. And immediately after doing that, the more acute tip dug into a strop I was using and a small portion of the tip snapped off. I wondered about the relatively deep scratches in the new edge acting like stress risers in influencing the fracture.

But fortunately, any other of my knives at more typical hardness haven't had any issues with chipping, after using diamond hones on them.

 

[annr]

I had one knife, a Kershaw Leek in ZDP-189, that made me rethink my use of a diamond hone when I reprofiled it. ZDP-189 is commonly hardened very high, into the mid-60s HRC. But it's much more brittle at such hardness. I'd reprofiled the edge to narrower geometry than factory. And immediately after doing that, the more acute tip dug into a strop I was using and a small portion of the tip snapped off. I wondered about the relatively deep scratches in the new edge acting like stress risers in influencing the fracture.

But fortunately, any other of my knives at more typical hardness haven't had any issues with chipping, after using diamond hones on them.

Have you figured out a way to test for this? Like they tell you to test a cleaning product on an area out of view in case it discolors the fabric? Or test paint color…

 

[Obsessed with Edges]

Have you figured out a way to test for this? Like they tell you to test a cleaning product on an area out of view in case it discolors the fabric? Or test paint color…

Honestly, I haven't. But the vast majority of the knives I use don't really push the limits for hardness anyway. Most of what I use are in steels like 420HC (Buck, Case @ HRC 55-59), Victorinox (HRC 56 by their spec) and Opinel (Sandvik 12C27Mod @ high-50s HRC). All of these are tough enough that they're really not prone to chipping at all, if they're heat-treated and tempered well.

My takeaway, from the ZDP-189 blade, was that I decided I don't need a steel at such hardness anyway. I reground the tip to an acute point again and it looks great (see below). But I'll never trust that one again for anything but very light use. I don't know if there was maybe some defect in heat treat or tempering with that one, or if what I encountered is typical for that steel when it's ground a bit too thin. I don't want to test such limits again, if I can help it.

 

[annr]

Honestly, I haven't. But the vast majority of the knives I use don't really push the limits for hardness anyway. Most of what I use are in steels like 420HC (Buck, Case @ HRC 55-59), Victorinox (HRC 56 by their spec) and Opinel (Sandvik 12C27Mod @ high-50s HRC). All of these are tough enough, that they're really not prone to chipping at all, if they're heat-treated and tempered well.

My takeaway, from the ZDP-189 blade, was that I decided I don't need a steel at such hardness anyway. I reground the tip to an acute point again and it looks great (see below). But I'll never trust that one again for anything but very light use. I don't know if there was maybe some defect in heat treat or tempering with that one, or if what I encountered is typical for that steel when it's ground a bit too thin. I don't want to test such limits again, if I can help it.

That’s the trouble when you try something new and things go wrong…or not as planned.

Mine was described as 440C “special,” I guess special referred to its special tendency to fall apart under stress. LOL

I checked and this knife has been discontinued, so something happened leading to its discontinuation…

 

[conan11]

I had one knife, a Kershaw Leek in ZDP-189, that made me rethink my use of a diamond hone when I reprofiled it. ZDP-189 is commonly hardened very high, into the mid-60s HRC. But it's much more brittle at such hardness. I'd reprofiled the edge to narrower geometry than factory. And immediately after doing that, the more acute tip dug into a strop I was using and a small portion of the tip snapped off. I wondered about the relatively deep scratches in the new edge acting like stress risers in influencing the fracture.

But fortunately, any other of my knives at more typical hardness haven't had any issues with chipping, after using diamond hones on them.

I broke my ZDP-189 tip prying on aluminum ceiling grid. My fault but it wouldn't have happened to most other knives.

 

[Obsessed with Edges]

I broke my ZDP-189 tip prying on aluminum ceiling grid. My fault but it wouldn't have happened to most other knives.

I guess that would affirm what I assumed about the steel - probably hardened too high for its own good.

Back when I first joined the forum 17 years ago, I seem to recall seeing much more discussion about ZDP-189, as it was more hyped back then. I think I did see some commentary along the same lines from some, about the toughness limitations of the steel and its tendency to chip or break.

 

[FortyTwoBlades]

Yeah a lot comes down to what you plan on doing with the steel. ZDP-189 is generally not a great choice where toughness is needed, but it does great striking a balance of hardness/wear resistance vs. the range of abrasives that viably sharpen it.

 

[conan11]

I might have been mistaken on breaking my tip on aluminum ceiling grid. It happened a long time ago but I think I used it sideways like a screw driver opening a ceiling access door. Totally my fault.

 

[Ace Rimmer]

I guess that would affirm what I assumed about the steel - probably hardened too high for its own good.

Back in the 1980s there were problems with TDI (Transamerica-Delaval) Diesel engines that, as I recall, were related to over hardened steel. Things like "pistons shattering like glass." Somebody apparently thought, "Well if 50,000 psi tensile strength is good, then 100,000 psi must be better!"

 

[annr]

Back in the 1980s there were problems with TDI (Transamerica-Delaval) Diesel engines that, as I recall, were related to over hardened steel. Things like "pistons shattering like glass." Somebody apparently thought, "Well if 50,000 psi tensile strength is good, then 100,000 psi must be better!"

That’s exactly what I thought happened in the case of my knife. Solve a problem without understanding the application.

 

[Obsessed with Edges]

That’s exactly what I thought happened in the case of my knife. Solve a problem without understanding the application.

Your earlier mention of your 440C blade's troubles made me immediately think of Buck's older 440C blades. An awful lot of their older 110 and 112 folders in 440C eventually ended up with broken tips. Saw a lot of those up for sale on eBay back then, and it always made me wonder what Buck's spec was for hardness in those blades. And back around the same time I was reading here about ZDP-189's toughness limitations at high hardness, I also remember reading about a lot of troubles with D2 blades breaking and also reading about how it was apparently much trickier to heat treat correctly without diminishing the steel's toughness.