At what grit do you stop looking for a burr?

[Zatx]

So I've recently wandered into the land of sharpening mirrored edges, and I've got a question about the higher grit stones.

When I'm sharpening a knife (and I'm reprofiling) on my Hapstone, I'll start with a 120 stone and work up a burr (on both sides) then move to 220 and 500. Each time forming as small of burr as possible. Once I get to the 1000 stone and beyond I stop feeling a burr form. I'll spend quite a bit of time getting all of the scratches out with each stone, but a burr never seems to form. Should I be spending more time and raise a burr I'll actually feel? How long do you spend on the higher grit stones? My shaptons cut so quick that scratches are removed after just a few passes.

I think one of the things that may be affecting my ability to feel the burr is that by the time I'm reaching the 1000+ grit stone I've been at the sharpening process for a while. Wetting and wiping the stones and equipment off has caused my fingers to get "prunny" from prolonged water exposure. This reduces their sensitivity. During my last sharpening session, I switched to checking for a burr using my KnivesPlus strop block. A rough burr causes the leather knap on this strop to raise thereby revealing its presence or lack thereof.

When I'm finished and have this nice mirrored bevel, I find it isn't nearly as sharp as I'd hoped until I do a slight micro-bevel. Do you think I'm creating a small wire burr and just not feeling it and my last micro-bevel is taking it off? Should I take a pass or two at a higher angle to remove any burr before progressing to each new stone?

What are your thoughts?

 

[TravisH]

I don't do mirror edges.

I stop checking for a burr about 600. Thereafter, I just count strokes per side.

 

[cbwx34]

You really only need to create / check for a burr once. A burr tells you you've reached and apexed the edge. After that you're just refining the edge and bevels... so no need to keep checking for and/or forming another burr... you're already there.

For your second question, yes, you need to develop a technique for removing a burr... there's typically one present at every level.... even though it may be hard to detect. But I wouldn't do a microbevel or higher pass at every level... save that for the end. I'll usually just do a couple of alternating strokes to reduce it before moving to the next step.

 

[Kyle363]

I can usually feel a burr up to my highest grit stones 8-10k and even when stop and edge using diamond paste on leather. Maybe your stones aren't flat and you're rounding your edge? I'm not sure since I free hand everything and don't have much experience with guided systems.

 

[Zatx]

I can usually feel a burr up to my highest grit stones 8-10k and even when stop and edge using diamond paste on leather. Maybe your stones aren't flat and you're rounding your edge? I'm not sure since I free hand everything and don't have much experience with guided systems.

I'm surprised you can feel a burr at 6k. At that point isn't the only thing that is happening is polishing/burnishing? (I'm not arguing that you couldn't possibly feel it, I'm admitedly here looking for information)

As far as flatness of my stones go, I have learned from our experienced forum members here that proper stone maintenance is a must, so I flatten my stones after every use. Love my Shapton Glass stones.

 

[Zatx]

You really only need to create / check for a burr once. A burr tells you you've reached and apexed the edge. After that you're just refining the edge and bevels... so no need to keep checking for and/or forming another burr... you're already there.

For your second question, yes, you need to develop a technique for removing a burr... there's typically one present at every level.... even though it may be hard to detect. But I wouldn't do a microbevel or higher pass at every level... save that for the end. I'll usually just do a couple of alternating strokes to reduce it before moving to the next step.

Thank you for the input, follow-up questions for you.

If I create the burr on my initial stone, and my goal is to only create it with that first stone, why not remove it at this stage?

Second, how do I avoid the burr, yet still remove all of the scratches the previous stone left behind? For instance, if I go from the 120 stone to the 500, by the time I've made enough passes to remove the scratch pattern from the 120, I've removed enough metal to create another burr.

 

[cbwx34]

Thank you for the input, follow-up questions for you.

If I create the burr on my initial stone, and my goal is to only create it with that first stone, why not remove it at this stage?

Second, how do I avoid the burr, yet still remove all of the scratches the previous stone left behind? For instance, if I go from the 120 stone to the 500, by the time I've made enough passes to remove the scratch pattern from the 120, I've removed enough metal to create another burr.

Your 2nd question answered your first. You will create a burr with the remaining stones... you just don't need to specifically create one or look for it... it's there. You're just working now to refine the edge, and/or polish the bevel. And you don't want to remove the burr after the first stone with higher passes, because the remaining stones may no longer reach the very edge... unless done very carefully, and as you've already figured out, you'll create a new one anyway. Like I said before, I will do a few alternating passes at each level (at the same angle)... this will remove the majority of the burr, and better refine the edge.

 

[HeavyHanded]

Thats it ^

The burr is going to be there, don't bother till the very end. On some stone compositions or finish methods the burr will take care of itself.

My usual method is to quickly reset the edge at whatever level is appropriate, most often a 1k JIS or medium stone. I'll go till the edge gets "sticky" (this is what I mostly use three finger sticky for).

Once the edge feels sticky I'll quickly look for a burr along the length. If it takes a bunch of passes and the edge hasn't gotten sticky, I'll start swapping sides so I don't get a larger bevel on one side.

I understand 100% about the fingers getting waterlogged, is a good idea with waterstones to develop habits of rinsing the stone and handling them that limit the immersion of your fingers, but some water swelling is unavoidable.

As I go up through the progression I use a hard wipe of the fingertips across either side of the edge, from spine toward/off the edge. I'm not looking for a specific stand alone sensation, but a comparative difference from one side to the other that lets me know the burr has flipped. Does one side feel catchier than the other, even slightly?

It might already be too small to see without bright light and a close look, but the fingertips, even if somewhat swollen will still be able to detect a difference. I'll take a look as well to see how the scratch pattern is progressing, but the tactile clue is my cue to switch sides.

By the time I'm at 6 or 8k I now have to press quite firmly to get a good read and now combine with visual detection depending. Still, any burr too small to feel comparatively is either standing straight up or extremely small.

If its a serious bevel reset (and most are), I start with a very coarse stone and once the burr is up I'll knock it back before moving on to the next stone. Still I use the comparative tactile test to see how small the burr is reduced. Once its almost too small to feel, I move on to the 400/1k etc and keep on with the same method, using the occasional sticky test as well. Grind and sticky tells me 89% of what I need to know and saves me from straining my eyes with a loupe.