Sharpening trouble based on abrasive

ejames13

ejames13

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Mar 30, 2015
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I've been sharpening on the Edge Pro for a few years now and have become pretty familiar with the ins and outs. Still, I'm not as pleased with my resulting edges as I'd like, and a lot of it seems to depend on the type of stone I use.

I'm able to get a consistently sharp edge using the Chef Knives To Go diamond plate set (140 --> 400 --> 1200) regardless of steel type. I'm able to push cut newsprint with the grain straight off the 1200 grit stone without any stropping. After stropping with 3 micron diamond compound on leather I can push cut newsprint against the grain. There does seem to be a small amount of burr remaining, however, if I look at the edge at just the right angle under warm light. I have not yet perfected removing that completely. I can produce a similar edge with the stock Edge Pro stones with just the 220 --> 400 progression. Any remaining burr off the EP 400 stone is almost undetectable, if one exists at all.

Now here's where I'm confused. If I move on from the EP 400 stone to 600 or 1k grit, my edge is no longer sharp. Straight off the 400 I'm push cutting newsprint with the grain and it catching hair easily, but off the 600 or 1000 there is a noticeable degradation in sharpness, and the edge will no longer catch hair. I experience similar problems if I use the Shapton Glass stones in 500 --> 2k progression. I can sometimes get an edge that will almost push cut newsprint with the grain off the 2k stone, but it's not quite as clean as the edge I get from the EP 400 stone.

I imagine the issue has to be my technique, but I can't figure out what I'm doing wrong. Some preemptive answers to potential questions:
- I use a stop collar to adjust for stone thickness
- I flatten my stones with CKTG 140 diamond plate after every sharpening
- This effect seems to be the case regardless of steel type, as I'm sharpening low-end generic stainless, through VG-10, S30v, and all the way up to high carbide M390.
- The resulting bevel looks clean every time, and I cannot detect a burr under warm light or with a 10x loupe.

Any insights would be greatly appreciated.
 
it's possible to remove the burr by swiping gently through soft wood, I always do that, regardless if I feel that I removed the burr by gently going over the edge a final time with the grit I'm currently sharpening with.

The more refined an edge, the less it 'saws' and might not even feel sharp to the touch. S30V for example, for me does not work well with a very refined edge, and feels less sharp when compared to stopping on a coarse/medium grit. To me, it feels sharper again after refining it to insanity with < 6 micron type finishes. S30V off a coarse stone rips through everything I put it to.

Low end steels will have more trouble getting/keeping a sharp edge.

Don't know what's going wrong for you, but maybe the above helps. You should be able to push cut though, regardless of the grit.
 
May it possibly be that you are pushing the edge through swarf on the stones you are having poor results with?

I have certain stones that I can never seem to get great results with even though the technique is the same, they almost seem to dull the edge left from the last stone, I suspect that’s what is happening in my case.
My problem stones feel frangible under the blade and my guess is that I am pushing the edge through the swarf which is dulling as much as it’s sharpening.
I don’t notice this happening with my harder stones that don’t wear as quickly.
It’s just a theory and may be unrelated to your dilemma.
 
If the giner stones are on the softish side you might finish with a few trailing passes.

Another possibility is to increase the grind angle a 1/2 to a full degree, to make sure you're removing metal from (and all the way to) the apex.
 
BJE said:
May it possibly be that you are pushing the edge through swarf on the stones you are having poor results with?

I have certain stones that I can never seem to get great results with even though the technique is the same, they almost seem to dull the edge left from the last stone, I suspect that’s what is happening in my case.
My problem stones feel frangible under the blade and my guess is that I am pushing the edge through the swarf which is dulling as much as it’s sharpening.
I don’t notice this happening with my harder stones that don’t wear as quickly.
It’s just a theory and may be unrelated to your dilemma.
Click to expand...

If this is the case it would have to be swarf from the abraded steel particles rather than stone fragments, as the Shaptons in particular are quite hard. Interestingly, I sharpened an 8-inch chef knife today using the Shaptons and was careful to keep the stone wet and free of swarf with each pass, and that seemed to help somewhat.
 
HeavyHanded said:
If the giner stones are on the softish side you might finish with a few trailing passes.

Another possibility is to increase the grind angle a 1/2 to a full degree, to make sure you're removing metal from (and all the way to) the apex.
Click to expand...

The EP stones don't seem very soft, and the Shaptons definitely aren't. I've actually tried increasing the angle in the past and I end up with the same result. The stone was definitely hitting the apex, because prior to swapping to the higher grit the knife was quite sharp. Once I swapped and increased the angle half a degree or so the edge was no longer catching hair.
 
ejames13 said:
The EP stones don't seem very soft, and the Shaptons definitely aren't. I've actually tried increasing the angle in the past and I end up with the same result. The stone was definitely hitting the apex, because prior to swapping to the higher grit the knife was quite sharp. Once I swapped and increased the angle half a degree or so the edge was no longer catching hair.
Click to expand...

Lighter touch?
Also the Shaptons are at least somewhat resinoid, a trailing pass probably an option.
 
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