Sharpening problems

[Kyle_4]

Hey guys,

Bit of a sharpening noob here so forgive me. In the past I have used sharpmakers and with some knives this works absolutely great and get its back to sharpness I desire. I recently bought an edge pro clone along with new edge pro stones (220, 400, 600, 1000) and an angle cube.

The first knife I sharpened was a ZT 0566 Elmax steel, I did the trick with the permanent marker on the edge and at 20 degrees per side it took all the permanent marker off. I did about 20 passes per side with the 220 and with each lower grit I raised the number of passes to roughly 50 passes per side with the 1000. The result was a very sharp knife, can slice paper super easily and I was quite happy with the result.

The second knife I tried was a XM-18 3" S35VN steel. I did roughly the same thing and at the end of it the blade edge looked almost mirror polished and I expected it to be super sharp. Instead it barely even cuts paper.

I am wondering what I did wrong, or if there is any pointers anyone can give me.

Thanks!

 

[ricklee4570]

Did you create a burr with the 220 grit on the S35 steel.

 

[Obsessed with Edges]

Did you create a burr with the 220 grit on the S35 steel.

^This.

Don't worry about counting passes or making the bevels polished, until first making sure a burr is formed at the first stone. In fact, you're better off not counting passes at all, because there are too many differences and variables from knife-to-knife; no two will sharpen up the same. When the edge is fully apexed, regardless of how long it takes, a burr will form along the full length of the cutting edge; that's when you know it's ready for the next step. When the burr is detected, then begin to use the following hones to gently remove it and refine the scratch pattern on the bevels. With each hone, don't be afraid to remove the first burr and re-generate a new, smaller & finer burr at each step; that guarantees you're reaching a full apex at each stage, without stopping short and leaving some of the previous grind pattern behind at the edge.

The upside to forming an obvious burr at the first step is, it'll be a LOT easier to refine the bevels and edge in the following steps. The heavy 'grunt work' of completely apexing is done at the first stage with the coarsest hone; then the following steps of refining happen at a much lighter and finer scale.


David

 

[Sawzall]

I hate to ask a stupid question but..... I'm having a hard time understanding forming a burr. I get it when sharpening a chisel or scissors but not when sharpening both sides of the blade, alternating from side to side. Anyone have photos or drawings of this? Thanks

 

[Obsessed with Edges]

I hate to ask a stupid question but..... I'm having a hard time understanding forming a burr. I get it when sharpening a chisel or scissors but not when sharpening both sides of the blade, alternating from side to side. Anyone have photos or drawings of this? Thanks

It's no different than when done on a chisel or scissors, in terms of how the burr forms. When the apex of the edge is honed until it's so thin it doesn't support itself against the hone, the very thin & weak steel at the apex will fold or roll to the side away from the hone; that's the burr. The usual next step is to hone from the other side and make the burr 'flip' in the opposite direction, which ensures the edge is fully apexed from both sides. Following that, the remaining steps should begin to abrade the burr away, or 'flip' it back & forth enough that it breaks away on it's own, leaving a crisp and durable apex behind.


David

 

[bodog]

It's funny the OP said that. I've sharpened some THICK S110V, B75P, and ELMAX. I've sharpened thinner S30V and S440V. I can get all of those legitimately hair whittling. When it came time for me to sharpen an S35VN XM18, it just didn't happen. I went through my normal progression and saw that it was actually fairly dull even though I'd fully apexed at each step. I went back to the beginning and the same thing happened again. At this point I was kind of stumped and took a softer 14C28N blade to see if I got a dud. Based on my extremely unscientific tests, the S35VN was harder. I ended up selling the knife to a rabid fan for what I paid for it before I figured out what was going on.

The OP is not alone. And yep, I got mine directly from RH.

 

[Sawzall]

Thanks for the explanation. It sounds like a lot of metal is being removed if a burr is formed and broken off at each grit change. .??

 

[Obsessed with Edges]

Thanks for the explanation. It sounds like a lot of metal is being removed if a burr is formed and broken off at each grit change. .??

At the very first step of setting the bevels and establishing the full apex, maybe. If done to full completion there, the metal removal to establish a smaller & finer burr at the next and subsequent steps should be very minimal. The crisper and thinner the apex is at the first stage, the less will have to come off in following stages; when really getting it 'right', it can happen in just a pass or two with each subsequent hone.

Having said all that, don't worry too much if each burr at each step is relatively heavy. With more practice and experience, it gets much easier to remove just what's necessary, and catch each burr very early, before they get too big.


David