BG-42 will not get sharp

T

Twindog

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I know how to sharpen a knife. My Manix in S30V is sharp enough to scare the whiskers off a flea. It will slice paper like a laser.

Not my Military CF/BG-42. I've reprofiled it (30 degrees inclusive). Found the burr. Taken it through grades of stone. Stropped it on two grades of grit paste. Used a sharpie and loupe. Certainly, it's sharp. It will cut stuff. But it's not very sharp. I have no trouble with any other kind of steel: ATS34, VG10, AUS8, Carbon V, 440A, M2, S30V. All sharpen up nicely.

What's up with the BG-42? Doesn't work for me.
 
I've found some of the super steels like S110V to take a "slippery" smooth edge that doesnt want to cut...if I rough it up with a medium stone, it becomes super sharp...its almost like polishing the edge does more harm than good...
 
Thanks, J.

I cringed a bit, but pulled out my medium stones and roughed up the edge a bit. I didn't see any great difference, maybe a little worse. When I try to slice paper, I often rip it. My Manix just slices cleanly without any effort.

Has to be the BG-42 because my sharpening efforts on other steels turn out fine. I think this must be the reason that Chris Reeve switched from BG-42 to S30V.
 
I know Vivi speaks extremely highly of BG-42, and he loves sharp edges so I doubt it is an issue with BG-42. I would try a 20 inclusive backbevel with a 30 inclusive microbevel, or just a quick 40 inclusive microbevel on your current sharpening job to see if the microbevel method will help you out. It works a tiny strip of steel at the very edge and takes much less time and effort than full bevel sharpening to get full sharpness. Unless your knife has a blown heat treat (highly unlikely, but possible) I would think there is some small thing amiss in your sharpening. BG-42 should easily be able to handle 30 inclusive or less, and be able to achieve very good sharpness. I've never used it personally but hear nothing but good about it, especially the BG-42 Millie.
 
Twindog said:
Thanks, J.

I cringed a bit, but pulled out my medium stones and roughed up the edge a bit. I didn't see any great difference, maybe a little worse. When I try to slice paper, I often rip it. My Manix just slices cleanly without any effort.

Has to be the BG-42 because my sharpening efforts on other steels turn out fine. I think this must be the reason that Chris Reeve switched from BG-42 to S30V.
Click to expand...
You might have a stinker. They do happen once in a while. My experience has been that BG-42 is much better at taking and keeping edges than S30V. YMMV.

How many times have you sharpened it? If this is the first time, sometimes 2 or 3 sharpenings will do the trick. I would try Gunmike's microbevel, and if that doesn't do it, take it back to coarse and sharpen for a good while then work your way back up.
 
Being used to sharpening CPM D2 and 440V, I had to be careful not to grind the blade away on my BG-42 Military. Compared to those steels (and even more so S90V) I find BG-42 very easy to put a razor sharp edge on, and it holds it better than it has any right to. It is possible that you got a bad one, but it is also possible that you are breaking off a burr, leaving a flat and ragged edge behind. I used to do that with ZDP-189 all the time until I learned to lighten up my strokes and trust the abrasives to do their job.
 
J_Curd said:
I've found some of the super steels like S110V to take a "slippery" smooth edge that doesnt want to cut...if I rough it up with a medium stone, it becomes super sharp...its almost like polishing the edge does more harm than good...
Click to expand...

Same with me.
 
I believe I'd have to go with Yablanowitz's explanation. I've got about 8 or 10 BG42 knives, including 2 millies. It's one of my all time favorites. It should get really sharp. It's one of the few stainless high speed, ball bearing steels and known for it's consistent batch quality and purity.

I do have one BG42 SOG stamped RC62 and at this hardness you need to be careful not to do exactly what is described above. The Millies seem much more forgiving, IMO. Perhaps SOG had complaints with it as later batches of the knives were stamped RC60.

It's not a steel I highly polish. I like the edge from 1200 to 2000 grit. It takes a wicked edge. Joe
 
i polished the edge on my 110 v shallot with the paper buffing wheel and it cuts like a mother. i'm going to convex the edge on it one of these days.
 
I appreciate the suggestions. I've both polished it and left it roughed up a bit on a medium stone. I've used the lightest pressure on the ceramics. The edge looks excellent. No glints. No damage except for a very tiny chip at the tip which is not visible with the naked eye.

I can get it sharp. But when I slice paper, which is how I test sharpness, it's just as likely to rip the paper in half as slice it. None of my other steels, when sharp, act this way.

Where I really notice it is in comparison to my Manix in S30V. The Manix cuts circles around the Military. I've sharpened them both to the same angle and with the same techniques.

And it's odd, because my Manix is an early one that chipped pretty bad when I first got it. But once I sharpened the chips out, it has been an awesome steel.
 
There's nothing wrong with BG-42. I can get edges to easily whittle hair. I've owned a CF/BG42 Military and got it as sharp or sharper than other steels. There might be something wrong with the steel on your particular knife. If there's something wrong with it, you may want to contact Spyderco and have them check it out.
 
BG-42 can get very sharp. Its high hardness and high wear resistance can make it difficult to sharpen. One of the reasons CRK switched to S30V is because it is easier to sharpen, more so than because it has better edge retention. I believe that all of the other steels you mention are easier to sharpen than BG-42, and it's always that last bit of edge that's the hardest. Hopefully someone will come along who can tell you exactly how to get it sharp...
 
MY millie (CF/BG42) takes a very sharp edge. I had to modify the edge though. It's more like semi convex now. I use coarse DMT stone, move to smooth Norton India, and finally strop it against cardboard. Very sharp.
 
Sounds like it might have something to do with blade geometry. I can get a decent edge on most of my knives, but sometimes, if the blade geometry is a bit wonky, it just keeps snagging no matter what I do.
 
I would really try raising your angle a few degrees to see if you get better edge sharpness. It only takes a minute or two to get a very sharp microbevel. If that still doesn't work maybe send it in to Spyderco. Also, if you have a loupe and a good light to put the knife under it makes it easy to see everything that is going on at the very edge of my knife. I use a 60-100x Radioshack lighted microscope that let's me see everything, even microburrs that I couldn't detect without it.

Mike
 
I don't have trouble sharpening knives. Just this one. I've spent the morning reprofiling it. The angels are correct. I've used the Sharpie. Under an 8x Loupe, the edge looks as good as my Manix edge. I don't seen any problems, just a very fine edge. In the skid test on thumbnail and plastic pen, the BG-42 grips like a champ.

I've stopped it 'til hell won't have it. When I put the paper that I've cut under magnification, it's easy to see that the S30V is cutting cleanly through the paper and the BG-42 is tearing its way through. I suppose, when it hits a tough spot in the paper it just rips.

I don't think it's my sharpening, although I'll acknowledge that's the safe bet. This steel will just not get that last bit of sharpness.

Here's a photo of the paper. It's not great, but hopfully you can see the difference. The S30V cut is the top edge and the BG-42 cut is the bottom edge.

DSC01369.jpg
 
you're not holding your tongue right :p:D. i have thoes days every now and then. just put it up and get back to it later. if you look at the edge as if you were going to cut your nose in half, do you see anything shine?
 
From the cuts in the paper it looks like both knives have burr's.
 
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