At what point do you stop looking for the Burr?

R

Rhodies

Joined
Jul 27, 2017
Messages
284
I would imagine it would be in the polishing phase, if you choose to progress that high e.g. 1000 grit and beyond? Am I wrong? Or do you continue to work a burr e.g. 1000gr and beyond?
 
I stop looking for burrs when I don't feel them. I hardly ever sharpen near 1000 grit. I remove burrs at 300-400 grit. Just me, I'll take my razor that high. DM
 
Look for the burr ONCE, at the first stage, to verify you've fully apexed the edge from both sides. Once you detect it by sight, feel or both, and remove it, you can then gauge progress with test-cutting in fine paper, FREQUENTLY, as you move up in finish. If you're doing a good job with that, you should see cutting continually improve with each step up in finish.

If you see cutting performance degrade somewhere in that sequence, that's when you need to recheck for a burr, or rounding or blunting of the apex; in which case, you need to backtrack a little bit and make sure to get the apex crisp again (look for the burr to verify that, again).

Bottom line, if you're careful with the refining steps after you've created and cleaned up the burr the first time in the sequence, you shouldn't have to (deliberately) make, or look for, a burr again. If you see it reappear along the way, it's no big deal, so long as it's still getting finer & thinner with each uptick in finish.


David
 
Last edited:
HeavyHanded said:
I stop looking when its gone.

I inspect for and expect one at virtually every step. Might not find one but it is a possibility right to the finish.
Click to expand...

What's your usual practice on burrs in your end-to-end sharpening process? When you get to apexing, do you do multiple passes same side and intentionally form a burr, or do you keep alternating sides trying to avoid/minimize burr creation? I'm hearing folks recommend differing approaches on this, similar to stropping, so it gets somewhat confusing and trying to harmonize what seems like the most logical approach to go with when you're at a level of basic/proficient freehand sharpening, but not advanced.
 
maximus83 said:
What's your usual practice on burrs in your end-to-end sharpening process? When you get to apexing, do you do multiple passes same side and intentionally form a burr, or do you keep alternating sides trying to avoid/minimize burr creation? I'm hearing folks recommend differing approaches on this, similar to stropping, so it gets somewhat confusing and trying to harmonize what seems like the most logical approach to go with when you're at a level of basic/proficient freehand sharpening, but not advanced.
Click to expand...


If I'm doing a lot of work - say lowering the angle initially - then I swap sides as needed to keep the bevel even or to even it up. Once it starts to get "sticky" I visually check to see how well the entire thing is ground shoulder to apex. I assume there's a burr and usually there is one, especially if the edge has been fully ground. I push it to one side and scrape it off with some high angle passes. If the edge is well formed I might be able to avoid the burr for the most part and still get the edge sticky, but that is normally something I only run into on knives that have been well sharpened after they left the factory.

I then make a few more swipes at the original angle. If running through a progression I repeat this procedure up and through. If microbevel, I spend an extra minute making sure the burr is gone first.

I won't kill myself getting rid of the burr until the finish, but I also don't want anymore of it in the works than I have to tolerate for time's sake. Eliminating/avoiding/keeping small the burr formed from my initial grinding is the most important step. I might make some high angle passes as I work to keep it small or prevent it from flopping sides too many times. I want to progress evenly and that usually means an uneven burr will form and for the most part be eliminated on the fly.

I don't do alternate sides by a count or anything. If the burr has become stubborn I stop and verify the effect of every pass or two at the most, swapping sides as needed to get rid of it. Doing this makes the work go faster, not slower - every pass is important. The less it flops, the stronger the attachment point and the easier it is to grind off. Chasing the burr is something to avoid.
 
[QUOTE="HeavyHanded, post: 17599391, member: 272877"
I won't kill myself getting rid of the burr until the finish, but I also don't want anymore of it in the works than I have to tolerate for time's sake. Eliminating/avoiding/keeping small the burr formed from my initial grinding is the most important step. I might make some high angle passes as I work to keep it small or prevent it from flopping sides too many times. I want to progress evenly and that usually means an uneven burr will form and for the most part be eliminated on the fly.[/QUOTE]
This is the manner I go about it as well. Yes, Part of the burr is eliminated at each stone or grit. So, at the final stone I already have a 1/2 way
burr free blade. Then w/ light stokes flip it (usually requires 3 times). Which reduces it as much as I possibly can on that final stone. If there is a spot that I can still feel a burr I'll remove that on a strop. DM
 
I stop worrying about the burr when I switch from stones to strops. My sense is that stones will always create a burr if both sides of the edge meet at the apex. That burr becomes smaller as strokes become shorter, stone grits become finer and strokes become lighter.

I get rid of the burr with a short, edge-leading stroke -- generally about an eighth of an inch. If the stroke is longer, you'll chop off the burr, but recreate it on the other side, what people call chasing the burr. But you're not really chasing the burr, you're recreating it. You can test this for yourself by using a very short, edge leading stroke on an obvious or stubborn burr. The burr won't flip, it will be gone.

So at the end of every stone grit, I cut the burr off in this manner. Even if I can't detect the burr, I know it's there.

When I finish with the strop, I don't worry anymore because proper stropping has limited ability to create a burr and, in any event, I couldn't chop it off with the strop using an edge-leading stroke.
 
Beyond 3k they are too small to feel so I check the consistently of the finish, the burrs are still there but too fine for me to detect. Ya still have to deburr.
 
Personally I find thay even when I'm at the final stages of sharpening where I have already knocked the burr off and I am now alternating sides on every stroke or two; I still have to check for burr formation because I might be putting uneven pressure on one side contributing to burr formation.

Checking for a burr is just a step in the sharpening process. Being aware of what is going on at edge level will make sharpening faster despite taking breaks from the stones to check the edge. Continued sharpening without checking will often lead to longer sharpening times as you mess up the edge. It is our natural tendancy to want to grind quickly when we feel like we were making progress and did something to mess up the edge. We check the edge and go "damn it was sharper 30 swipes ago." Now we have a tendancy to want to grind and grind to get back atleast to that previous sharpness getting frustrated. Check the burr often. I use a combination of my thumb, thum nail and paper cutting to try best to understand what is going on at the edge.
 
I can't say that I've ever experimented with "clarity/cripsness of the burr" versus whether you only stroke the abrasive in the spine-to-edge direction (versus scrubbing, or just edge-to-spine), but if any of you are woodworkers and have ever sharpened a card scraper (where you INTENTIONALLY create a burr with a burnishing tool), you always and only move the burnishing tool in the "spine to edge" direction. And in the case of a card scraper, there is no apex (you create a burr on one side of a squared edge). The point being, an apex is definitely not a requirement for a burr; you just need an edge (and even a 90 degree edge works).

Anyway, from the card scraper example I'd conclude that burr formation should be more effective if you only stroke the abrasive in the spine-to-edge direction. Of course, my card scraper analogy could be a poor one, relative to a knife edge.

In terms of metallurgy, I suspect (but I'm not certain) that certain alloys will "smear" more easily and therefore a burr is easier to obtain and feel, while maybe some alloys are more brittle and maybe a burr forms but it breaks off at the slightest touch.

It (burr formation) may even have some relation to the heat from the friction of the abrasive (again I'm not sure; just floating the possibility), so for example if you do multiple fast strokes with the abrasive, the heat from friction would be higher and maybe burr formation is more likely. At the other extreme, if you do very slow strokes, with time between each one where heat from friction doesn't build up, maybe burr formation is more challenging?
 
I sharpen by hand on ceramic. Sometimes i stop at the spyderco medium brown stone, sometimes the fine white stone. I get a really fine edge and the burr cannot be seen or felt. At this point my knife is very sharp and can easily slice paper towel and hairs will jump off arm cutting with just the weight of the blade. sometimes i use a bright flashlight, a headlamp works great, and you can see a tiny little amount of burr left. Then i make very light and short strokes on the stone until it is gone. Then i will move to a strop loaded wjth green compojnd and do 2 to 3 very light passes on each side. It is incredible how sharp it can get with just a couple minutes on the spyderco double stuff and a few light passes on loaded strop.
 
Last edited:
It seems so simple now but it took me a couple years of learning by sharpening about once a month. I didnt have anyone to teach me. In the beginning i wasnt even aware of how sharp a knife could really be. practice makes perfect. it is like learning to drive a manual transmission. It takes some time to learn but once you do it will seem easy.
 
Twindog said:
I get rid of the burr with a short, edge-leading stroke -- generally about an eighth of an inch. If the stroke is longer, you'll chop off the burr, but recreate it on the other side, what people call chasing the burr. But you're not really chasing the burr, you're recreating it. You can test this for youself.
Click to expand...
I tried this and it did not work. DM
 
jalapeno said:
I can't say that I've ever experimented with "clarity/cripsness of the burr" versus whether you only stroke the abrasive in the spine-to-edge direction (versus scrubbing, or just edge-to-spine), but if any of you are woodworkers and have ever sharpened a card scraper (where you INTENTIONALLY create a burr with a burnishing tool), you always and only move the burnishing tool in the "spine to edge" direction. And in the case of a card scraper, there is no apex (you create a burr on one side of a squared edge). The point being, an apex is definitely not a requirement for a burr; you just need an edge (and even a 90 degree edge works).

Anyway, from the card scraper example I'd conclude that burr formation should be more effective if you only stroke the abrasive in the spine-to-edge direction. Of course, my card scraper analogy could be a poor one, relative to a knife edge.

In terms of metallurgy, I suspect (but I'm not certain) that certain alloys will "smear" more easily and therefore a burr is easier to obtain and feel, while maybe some alloys are more brittle and maybe a burr forms but it breaks off at the slightest touch.

It (burr formation) may even have some relation to the heat from the friction of the abrasive (again I'm not sure; just floating the possibility), so for example if you do multiple fast strokes with the abrasive, the heat from friction would be higher and maybe burr formation is more likely. At the other extreme, if you do very slow strokes, with time between each one where heat from friction doesn't build up, maybe burr formation is more challenging?
Click to expand...


I've considered using my waterstones with an ice bath but have never given it a try...

In my view, burrs are a product of ductility. The more ductile the steel, the more it will be prone to burring (all other things being equal). This is why high hardness steels tend to be very forgiving of burr formation, while some stainless will be drawn out considerably by the abrasive.

Trailing passes tend to make larger burrs because they are drawing the steel out as well as (to a lesser extent) pushing it out of the way, whereas on a leading pass the abrasive is deforming the steel out of its immediate path with maybe more force than the trailing pass, but not drawing it out at all.
 
Twin, what happened was it did not remove the burr. As it requires more stone surface to sand it off. I got good results on grinding off the burr
on a 4-5" pass of a 8" stone. Using light pressure on the push on a small reduced burr. If the burr is larger it requires more sanding on the stone. The steel was 440C which is burr prone.
Heavy, agreed. DM
 
Once a burr is present, I wonder if chilling it before the removal swipe would make it snap off easier/cleaner. For example, use a spray duster (a can of compressed air (it's not really air, but that's the common name for it)) to chill the knife edge down first.

I know the spray duster cans get extremely cold after spraying for an extended period because I have set a can down on a wood table and the ring at the bottom of the can is so cold it "burned" a dark ring into the wood (don't try this at home). But the "air" coming out is pretty cold as well.
 
HeavyHanded said:
(...)In my view, burrs are a product of ductility. The more ductile the steel, the more it will be prone to burring (all other things being equal). This is why high hardness steels tend to be very forgiving of burr formation, while some stainless will be drawn out considerably by the abrasive.
(...)
Click to expand...

I agree with that.^

Ductile steels like 420HC, VG-10, ATS-34/154CM will make burrs that are more stubborn to remove, sometimes even when they're very thin; they just fold on the edge like foil. And ATS-34 burrs, that I've seen, continue to amaze me with their strength and toughness at fairly high hardness, even at 60 HRC or slightly higher.

Steels of higher hardness (less ductile) will still form burrs, but they're a lot easier to remove; a lot of the time, they'll just crumble away or break off on their own, when they become thin enough. Good 1095 at HRC ~60 or so, and ZDP-189 (low-mid 60s HRC) are very easy, with their burrs just breaking away with a brush of the fingertip, when they've been adequately thinned. To be honest, I don't think I've ever seen a sizeable burr on ZDP-189, for that matter, at the hardness it's typically treated to.


David
 
You must log in or register to reply here.
Back
Top