Tips on sharpening CB Leek

F

flarp

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Sep 7, 2011
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Any tips on sharpening the composite blade Leek? I am encountering some difficulty.

I can get the edge sharp enough to make smooth effortless cuts through paper, slice through plastic blister packs with ease, and even shave arm hairs. When I take that same edge to thicker cardboard (even just single ply stuff), nylon cable ties, or packing straps, it takes quite a bit of effort to cut through. The factory edge handled all those with ease, so I must be doing something wrong.

Does the CPM-D2 need to be sharpened differently from other steels? I haven't had any issues sharpening other knives (mostly AUS 8, 8Cr13MoV, and a couple of VG-10 and 1095). I'm using a "fine" grit Arkansas stone for the sharpening and a leather strop infused with green compound to finish. Searching around online, I have found some non-specific comments about tool steels being different or more difficult to sharpen, but no real details beyond that.

The blade was still reasonably sharp before I started my re-sharpening attempt. I just noticed it was starting to take a bit more effort to do some cutting (specifically cardboard, packing straps, and cable ties), so I figure I'd touch up the edge. I think now, I might have actually made it more difficult to cut those materials. I use paper cutting as sort of a baseline for before and after tests when I sharpen, and that did seem to indicate some edge improvement from my efforts.

Any advice would be much appreciated.
 
I second his question, I have the JYD II and would like to know this info as well. I am using a paper wheel.
 
The Paper wheel will give a polished, not "toothy" working edge. I'll wait with somebody with more experience to chime in.
 
flarp, you might want to try a coarser edge so its a little toothier. bobsig, how many passes are you making on the slotted wheel on the jyd? send me an email with your number and i'll give you a ring. i have some tips that might help you out with the wheels.
 
Does the Leek / D2 steel need a toothier edge vs. a polished one? I have very little experience with CPM-D2. Prior to getting the CB Leek about 3-4 weeks ago, I had never used any blade with this steel. Right now I have a fairly polished edge on it (after I re-sharpened), but I don't remember if the factory edge was toothier. Whatever the factory edge was, it cut great on both thin and thicker materials.

I'll try touching it up on a medium stone to see if that helps. Thanks for the tips. If anyone else with more experience with this knife or steel can chime in, that'd be great. Thanks.
 
you could have went too fine which would make the edge slide so you need to try a little coarser grit. did you change the angle any?
 
I did not change the angle any (at least not deliberately). I'm sharpening free-hand, so of course, there's bound to be minor changes. I did my best to stick to the original bevel, and I can't see any formation of any new bevel (at least under a 20x magnification jeweler's loupe). I was just doing a touch-up sharpening to begin with, so didn't grind away enough steel to completely change the bevel.

I made a few passes over a medium Arkansas stone, and it seems to have made a big difference. I can feel more bite on the edge just touching it with my fingers, and with just a few test cuts on cardboard, it is making the cuts far smoother now. I can't shave with it anymore (it snags and pulls on hair), but it actually does a better job now of cutting the materials I more typically task it to.

Is this a characteristic of CPM-D2 (needing to be a bit toothy to cut well)? On my other knives, polished edges seems to cut better for both thin and thick materials. If the CPM-D2 performs better like this, it certainly makes maintenance going forward easier. :)
 
did you strop it? i was just talking to a member who has one and he convexed the edge. he said it cuts way better. you might want to give a convex edge a try.
 
if its anything like cpm-154 it will prefer diamonds, try going 600 grit or 750 on a diamond for 15-20 passes per side then a 1200 grit doing the same

it should be like a laser when done.
 
D2 responds nicely to diamond and silicon carbide (like wet/dry sandpaper). In the case of your knife, I'm betting the factory edge isn't fully apexed, which really creates a lot more resistance in the tougher materials. Cutting paper & blister packaging is pretty simple with a less-than-perfect edge with some toothy burrs or a wire edge on it. But the tougher materials won't be fazed by those, as the shape & condition of the true edge will do most of the grunt work. I think you'll have a hard time doing any significant improvement to CPM-D2 with a fine Arkansas stone (not very aggressive on steels like that). Get yourself some wet/dry sandpaper in grits from maybe 320 thru 800 (or higher, if you'd like to polish your edge). For simplicity's sake, I think a working edge around 600 grit would suit you well, for what you're doing. Many will argue that going higher in grit will somehow diminish cutting. But that only happens if it's done with poor technique (bad angle control), which is what will 'round' the edge. Some also seem to equate a highly polished edge with a weak (thin) edge. But a thin edge has nothing to do with the polish (it fails because it's too thin, which can happen at any grit).

Convex can work fantastically in tough materials like carboard and heavy plastics (like cable ties). Cutting those is much more impacted by the shape & relative smoothness (finish) of the 'shoulders' BEHIND the edge (and, of course, the edge itself must be fully apexed & sharp). My best cardboard-eating blade is a Buck 112 (440C) with a convexed edge and finished to above 2000 grit. Really slick cutting in heavy cardboard, and very durable. I strop it with Simichrome on leather most often for maintenance. If it needs a little more than the strop can do alone, I'll take it back to the 1000 - 2000 grit sandpaper for just a few edge-trailing passes (as if stropping). Then follow again with the Simichrome strop.
 
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Sandpaper may be a better idea than the stones. I'll try that. I did notice that the Arkansas stone wasn't cutting quite as effectively on this knife (even compared to my Delica and Endura, both VG10), and it took a fair amount of stropping to have any visible effect. I don't have any diamond stones handy, but I've got some 320 grit sandpaper (although of the dry variety). I'll pick up some 600 grit wet/dry and try that out. Fortunately, the edge was still fairly sharp, so this recent effort really was more a touch-up than a complete re-sharpening. I don't think I thinned out the edge by much when I was sharpening. In fact, I can still see some of the original lines from the factory grind.

The convex edge looks interesting as well. I found instructions online for making a Hoodoo Hone that looks pretty straightforward. I'll give that a shot on one of my other knives for now (something with an easier steel to hone). Thanks for the suggestion.

Right now, the slightly toothy edge from scuffing it up a bit on a medium stone seems to be working fine. Just broke down a couple of boxes after a Costco run, and it ate through those with ease (and some of those boxes are really stiff and sturdy). We'll see how long this current edge holds. Next re-sharpening, I'll skip the stones and strop and try just the sandpaper.

This is my first knife with CPM-D2, so it may just take some more practice and trial-and-error.
 
i really like a convex edge compared to a v. some of the knives i make are chisel grinds and i put a half convex edge on them. talk about a sharp edge. i have made some that will scare you :D.
 
richard j - I have the slotted wheel, and then I have another paper wheel that isnt slotted at all. I ruined the slotted one with my axe when I was playing around... learned a lesson there. So I have been using the other one, it was used on wood turning chisels and has a groove down the center but it has been been doing alright, was able to get my Kershaw Boot knife very sharp. I had to grind down some kitchen knives and re sharpen them and was able to get those sharp too, but not too much luck with the D2. I dont know if it is a good idea but I add a buffing compound on the wheel and it seem to help a bit. As for the number of times i swipe it per side Im not too sure. I just try to keep them even counts per side, then I strop it a bit when done. Ill send you an email.

Thanks,
BobSig
 
D2 and CPM-D2 are pretty wear resistant... I doubt the Arkansas will do too well against it. From what I recall, SiC and diamond tend to work well. Being wear resistant, it will likely take a good deal longer to achieve the same results as with a "softer"/less resistant steel -- particularly by hand.

I have a Kershaw with a D2 composite blade. I wound up setting the bevels with my belt grinder (220 grit belt), then refining the bevels with a 600 grit belt, then moving to the slotted paper wheel + rouge, then a quick hand strop on loaded linen. It whittled hair, no problem. Belts were Trizact, if it matters.
 
I've had a CB Leek before. I think it has a hard time cutting because of its grind. The flat saber grind is pretty darn thick. So even though you have a very sharp edge, cutting can be somewhat tough.
 
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