Can't get Benchmade D2 steel sharp with Sharpmaker

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dtyndall

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Mar 7, 2015
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Ok so I'm new to the world of sharpening. Just bought a Spyderco Sharpmaker to sharpen up all my knives. I have a year old Benchmade 375 Adams in D2 steel that I rarely if ever use, however it is mostly dull. I set up my Sharpmaker earlier today, using a sharpie to trace the edge on the 375. I determined that the 40 degree angle was best, as it was wiping away the sharpie.

From here, I began with the medium flat stones on the left side of the blade. I developed a burr on the right side, then began sharpening that side until I developed another burr on the left side of the blade.

Once both burrs were established, I used the fine stones for a good 30 minutes, alternating medium and light pressure. After probably an hour of sharpening, the knife still fails to even cut paper. What gives? Am I doing something wrong? Any input that may help?
 
dtyndall said:
Ok so I'm new to the world of sharpening. Just bought a Spyderco Sharpmaker to sharpen up all my knives. I have a year old Benchmade 375 Adams in D2 steel that I rarely if ever use, however it is mostly dull. I set up my Sharpmaker earlier today, using a sharpie to trace the edge on the 375. I determined that the 40 degree angle was best, as it was wiping away the sharpie.

From here, I began with the medium flat stones on the left side of the blade. I developed a burr on the right side, then began sharpening that side until I developed another burr on the left side of the blade.
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After producing a verifiable burr at that stage, it would've been best to STOP and test how the edge is actually cutting before moving on. With the burr at the edge, it would still be expected to snag a bit on paper when cutting it. But testing cutting should at least verify the edge CAN cut paper (albeit roughly), before attempting to refine the edge. The medium stones could also be used to gently de-burr the edge; if that's done very well, paper-slicing should be a breeze with no additional work on finer stones.

Once both burrs were established, I used the fine stones for a good 30 minutes, alternating medium and light pressure. After probably an hour of sharpening, the knife still fails to even cut paper. What gives? Am I doing something wrong? Any input that may help?
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This is where it likely went downhill. With a very long, extended session on ceramics, it becomes difficult to stay consistent in held angle, and will likely produce an edge that's either rounded off or overpolished, or both. The edge should come off the medium stones already cutting paper cleanly at the least, after which any additional refinement on finer stones should be very, very light and minimal, taking no more than a few minutes' time (maybe 5 minutes or less, even down to a handful of passes on each side, taking just a minute or so). The very best indicator of an edge done right, is when it responds almost immediately to the first 1-3 passes on the finishing stones, indicating the edge was truly 'ready' for refinement. If it takes very long at the finishing stage, that usually means the edge wasn't really complete coming off the earlier/first stages of sharpening, meaning it either wasn't fully apexed, or fully de-burred, or both.


David
 
So basically it doesn't hurt to take my time on the initial step/medium rods? It sounds like I was rushing through the first part...
 
Where did you mark the "edge" with a Sharpie?

I find that many people make the mistake of actually marking the shoulders only....

You need to take the edge and draw it through the Sharpie like you are cutting through the tip (do it lightly, and no, you won't cut the tip down the middle...!!)
 
I draw a line on the actual edge, as well as partially on the shoulders. Within a few swipes on the Sharpmaker, the sharpie will be gone completely.
 
dtyndall said:
So basically it doesn't hurt to take my time on the initial step/medium rods? It sounds like I was rushing through the first part...
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Right.

As OwE said, it should have been paper-slicing sharp with just the Medium rods.

In fact, I stop at Medium for my kitchen knives. The Medium rods are ~1000grit. Fine enough for most edges. The Fine is for refining an already sharp edge.
 
You can get shaving sharp with the medium rods, in fact surfingringo can get hair whittling sharp with them, I suspect you started to fatigue and or lost your coordination and weren't consistent enough. The learning curve on the sharpmaker for wear resistance steels is probably around 25-50 hours of use, it just takes that long to establish the motor control needed to keep it at roughly the same angle for extended periods. My advice, once you have a bevel established, go slow and light. Its pretty common to dull a knife with finer stones when you don't have the experience and coordination developed yet.
 
In addition to above suggestions I'd also take a look at the rods themselves - if they are loaded up that could make the difference. I don't know what BM runs their D2 at for Rockwell, but it some very wear resistant stuff and the rods are loaded they won't be able to cleanly work that steel.
 
dtyndall said:
Thanks for all the input guys. Will keep all of this in mind.
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If it makes you feel any better, I think all of this is part of the normal learning curve for the Sharpmaker and similar V-crock sharpeners. I mentioned the points I did, because I'd also run into the same issues when figuring out how to use them. In particular, the tendencies to vary the held angle over a long sharpening session and overwork the edge on the finer rods are both VERY easy to do, and I ran into the same issues with the edge becoming rounded off and overpolished. With these setups, it's really important to minimize how much time is spent and how many passes are made, making the best use of the 'coarser' rods to get the edge as good as it can be before attempting to refine it on the finer rods. None of the ceramics will remove metal very fast, so taking advantage of the coarsest available hones is important, to minimize fatigue-induced errors during refinement. For blades that need much more work than can be done efficiently on the medium rods, the optional diamond or CBN rods would be worthwhile.


David
 
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I don't know what BM runs their D2 at for Rockwell, but it some very wear resistant stuff
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According to Benchmade's website, their D2 is hardened to 60-62.
 
CSSA said:
According to Benchmade's website, their D2 is hardened to 60-62.
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Thanks for that -

While certainly possible to use, I don't think ceramics make a good matchup at all in this case. Would be very easy to blow the carbides out of the surrounding steel if the angle should go too high even with reasonably light pressure. Is also possible to mistake those blown carbides for a burr once the edge is thinned out.

Silicon carbide at the least, or diamond will do a much better job IMHO.
 
SBaker34 said:
Is d2 more wear resistant than S30V though?
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Theoretically no, but bound into a high RC steel, it makes for a very wear resistant edge even though Vanadium carbides are tougher then the Chromium ones in D2.

The challenge comes about because the carbides in D2 are so large. Using something like SiC that can fracture down a bit is less likely to displace the carbides as it grinds. Even AlumOx as in a waterstone should have an advantage over ceramic in this regard.

This is just an opinion, in good shape and with good angle control the ceramic is still capable of working the steel, but will be far less forgiving of angle and pressure variations.
 
I agree totally about those steels being nightmares witg ceramic. But it just required more skill. I've never used D2 though. S30v and zdp189 were the worst I sharpmakered with
 
Dmt x-fine is how I get my D2 and s30v sharp, I bought this stone specifically for these steels.
 
HeavyHanded said:
Theoretically no, but bound into a high RC steel, it makes for a very wear resistant edge even though Vanadium carbides are tougher then the Chromium ones in D2.

The challenge comes about because the carbides in D2 are so large. Using something like SiC that can fracture down a bit is less likely to displace the carbides as it grinds. Even AlumOx as in a waterstone should have an advantage over ceramic in this regard.

This is just an opinion, in good shape and with good angle control the ceramic is still capable of working the steel, but will be far less forgiving of angle and pressure variations.
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I agree with that. Too much pressure on the edges (especially) of the ceramic rods could be risky on harder D2. I have an older limited-run (1 of 50) D2 folder from Benchmade that I purchased secondhand back in the early 2000s, and it came with a noticeable CHIP at the edge, near the tip of the blade. Looking closer with a magnifier also revealed a CRACK extending upwards from the chipped area, into the upper portion of the edge; the steel was obviously brittle in that portion. I'm assuming that was more a defect on BM's part, and probably not representative of a well-tempered blade. But it still brings to mind the risks in using very hard ceramics on very hard D2 edges, as chipping or cracking might result with too-heavy & focused pressure laterally against the edge. If using ceramics on it, like the SM's rods, I'd limit usage to the flats only, and not the corners. That'll at least help distribute pressure over a wider section of the edge, though care still needs to be taken to keep the stroke very light and controlled. Otherwise, a diamond hone would be my preference for it, as it'll still cut the large carbides cleanly with a still-very-light touch.


David
 
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