Buuuuuuurrrrrr!!!!

[nozh2002]

Hey, Vassili,
Do you still use your waterstone? Have you tried sharpening your higanokami on the strops and have you tested them for thread cutting?

Before going with powder I form edge if nessesary using eather Diamond Eze Lap or Waterstones. I found similar as for Higonokamy problem with other japanese blade and also with bulat from Ivan Kirpichev (it is very interesting, it looks like it gain hardness in time - I dont have this problem few monthes ago when I just made knife).

This knife I currently testing was sharpened by 250 and 800 waterstones - it takes time, this why I prefer powder on leather.

I did not tested Higonokamy yet. Too much things I like to do - I need to work full time for this!

Thanks, Vassili.

 

[Blop]

I,m Going insane here guys!!!!
I read this thread five different times and tried to use all the techniques on some knives i was taking camping this weekend. I could not get a shaving edge from a coarse stone like Cliff Stamp says i can; with the 45 degree angle approach from jeff, I just seem to be dulling my knife (even after regrinding); and Im not seeing a burr at any stage after using these steps, EXCEPT after i progress from my finest stone to my triangular ceramic rod!!!!
NO BURR until I run my already shaving sharp knife over the fine ceramic a few times!! Once it shows up on this sucker, the only thing that gets rid of it is going over it at a REALLY high 45 degree angle like TEN times; and this leaves my actual cutting angle when i whittle or cut anything waaaaaaay too high for me, plus, any ability to shave or slice paper is gone due to the blunt edge!!!
WHAT IS GOING ON HERE????!!!!!
Could it be that my ceramic is just too worn out to be effective at cutting??
It seems like all my problems are stemming back to that thing. It is pretty old and getting smooth, so maybe it is just abrasive enough to create that micro-burr on an already super- fine edge, but not take it off????
Thank you all for your patience and dilligent responses..

Do less! Form the edge on the coarse stone. You will never form half the edge on the coarse and the rest of the edge on the following stones or whatever you take.

The first step, sharpening on the coarse is the most important step.

Any following step: Do less strokes. Try just three to four times per side.

Stone and steel must fit. Softer steels like 420 can´t go well with hard medias. A soft edge will deform easily on hard ceramic. More easy if the cermic is a thin rod.

If the edge is sharp without the ceramic, and just using the ceramic creates the burr, throw the ceramic away.

 

[Cliff Stamp]

The first step, sharpening on the coarse is the most important step.

When people say sharpening hard or high alloy steels is difficult this is the reason. Either they start out with too fine a hone, or don't do enough work with the coarse one. Try a 220 grit SiC waterstone, which will eat through the hardest and most wear resistant of steels like butter. It can even take out visible chips in minutes, or reform edge angles. It doesn't pay attention to the steel being 52100, 420HC or S30V, they are all equally ground very fast.

-Cliff

 

[Cliff Stamp]

Just an addition to the commentary by Jeff and others in the above, recently I have reprofiled some edges down to ~5 degrees per side and then applied a 20 degree microbevel. I have found with the edge as acute, it is very difficult to keep it from burring badly with rods are used to set the micro-bevel.

To solve this problem I preset the edge at 15 degrees per side and then finish with a 20 degree bevel on top of that one. Thus the edge is triple ground 5/15/20. This allows a crisp edge formation with little trouble. Resharpening can be done on the 20 degree setting .

-Cliff

 

[Jeff Clark]

Hi Cliff, maybe you could edit your post a little to make it clearer. Am I right to understand that micro-beveling at 20-degrees created a burr problem for you? Or micro-beveling at 20-degrees failed to remove or maybe flopped-over an existing burr from your reprofiling? And somehow micro-beveling at 15-degrees, then 20-degrees worked better.

I'd like to get a more detailed explanation since that almost seems backwards to me. In particular which rod grit did you use for your micro-bevel, did you use the flats, how much pressure did you use, what grit did you use for the last phase of your 5-degree work, do you think the burr that is giving you problems originated during the reprofiling or during the 20-degree micro-beveling?

I usually finish down to a 600 grit belt running into the edge when I reprofile and then smooth the surface a bit more freehand on a 1000 grit water stone. I come close to the same angle (a little bit higher) using the Sharpmaker rods, medium-edges to medium-flats to white flats. At this point I deburr very lightly at 40 degrees per side using the medium-flats. I go back and remove that obtuse bevel at around 10 degrees per side by lightly using the medium-flats and the white-flats. I micro-bevel using the flats of the UF-grit rods at about 12 degrees. I sometimes go for 15 or 20 degrees for a microbevel. I don't notice a burr problem when I go to 20 degrees, but I guess I usually do a 15 degree micro-bevel first and then just touch it a little at 20 degrees. I really resist going as obtuse as 20 degrees so I compromise by doing some 15 and some 20.

I just have never noticed more of a burr problem at 20 degrees than 15 degrees. It seems weird.

 

[Cliff Stamp]

I create the five degree edge with a 220 SiC waterstone, I then polish it with a 1000 grit AO waterstone, I used to go up to 4000 but found it made no difference.

I create the microbevel with the flats of the medium rods, I don't use the corners unless I have to on recurves. They create really high pressure and tend to roll edges readily.

I found that the the edges at 5 degrees were too thin to stand up to honing on rods when I jumped up to 20 so I preset the edge at 15. This seems to work better on the steels which burr readily.

It is possible to run the 5/15 or 5/20 edge clean, but I find that it is just easier to get crisp edge with the intermediate step. This is with softer stainless, under 60 HRC. It is different with the harder carbon steels.

To be clear, I still do deburring on all stages, as you describe, create the edge, deburr and then rehone. I have checked the sharpness as there were some concerns that your method was dulling edges with the large burr angles.

In fact I have been getting significantly better numbers. I now see ~100 on thread as decent whereas a year or so ago I would have called that sharp. Now I am pleased if I average a solid 75 or so on the thread.

-Cliff

 

[Jeff Clark]

I'm still at kind of a loss as to how the stress on the edge is worse at 20-degrees than at 15-degrees. The lateral component of force against the edge will be higher at the lower angle. Considering the blade as a beam the deflection of the edge-end of the beam should be greater with force applied at 15-degrees than at 20-degrees. Maybe the pressure along the area of hone contact is higher with the 20-degree angle. Maybe there is more chattering of the edge as it catches and slips down the hone surface. I wonder if you'd get a different effect if you oiled the rods before honing at 20-degrees. Maybe the edge is slightly buckling. Maybe it would work fine if you used the white rods at 20-degrees.

 

[Cliff Stamp]

The lateral component of force against the edge will be higher at the lower angle.

We must be looking at this differently. Let gets specific. The edge on my reground Sebenza is 2 mm wide, the rods are a cm across. If I apply 5 lbs to the rods the pressure is about 65 psi on the edge. However if I apply a the 20 degree bevel the contact is made at about a 0.1 mm strip (check under mag) and thus the pressure is ~1300 psi.

-Cliff

 

[Jeff Clark]

Hey Cliff, Notice that I was careful to distinguish force from pressure. I assumed that before you started applying your microbevel you didn't have a 2mm bevel you had something more like 5mm. Whether you hone at 15-degrees or 20-degrees you won't be working on that 5mm strip you are working on some miniscule, but widening stip right by the apex. Since the edge is extremely thin in that region I expect it to bend elastically away from the hone until it reaches a force balance. It also tends to distribute the honing pressure across a somewhat complient surface.

I assumed that the edge would bend over further when honed at a lower angle since the force would be more nearly perpendicular to the plane of the blade. This would apply more bending stress to the blade. If I think of the edge like a cantilever beam I am putting the beam under more shear and tension if I push on it downwards than if I push on it end-on. The end-on force component tends to put the metal under compression where it is relatively strong.

I see how the pressure will start off very high whenever you hone at an angle that is significantly different than your base bevel, but I don't see how 15 vs 20 degrees is going to be that much different in that regard when the base bevel is at 5 degrees.

I wonder if the effect is sort of a kinking and rolling process. The apex of the edge is very thin. If you hone it with any force at a high enough angle it will buckle over and start to curl to the opposite side. If that is true you need to start the microbeveling process with whisper-light strokes and not move on to appreciable force until you have widened the microbevel significantley.

I guess that is sort of what I do. When I microbevel I apply miniscule force. I know that I am working on a very weak section of edge and I don't want to over tax it.

PS. I don't think of 1300 psi as being very high stress for alloy strain. Even 1020 steel is rated 10x higher than that.

 

[Cliff Stamp]

I assumed that the edge would bend over further when honed at a lower angle since the force would be more nearly perpendicular to the plane of the blade.

Ok I see what you are saying now, if you consider the two components of the force, the parallel and perpendicular, the force across the edge gets much higher at lower angles, and in the extreme goes to zero if you hone at 90 degrees. I never considered that which is kind of amusing as it is a basic principle of force mechanics.

I see how the pressure will start of very high whenever you hone at an angle that is significantly different than your base bevel, but I don't see how 15 vs 20 degrees is going to be that much different in that regard when the base bevel is at 5 degrees.

It doesn't, the 15 degree edge is not trivial to hone clean either. However 20 on 15 is very different than 20 on 5 because the edge is three times thicker at a given distance back for 15 vs 5, and thus the strength is ~27 times stronger.

It could be that I just had a run of better luck, but I have done it a few times and found it easier, as with everything, repeat, repeat, repeat and then when you are absolutely sure check again.

I am running some trials now looking at edge retention on 15 vs 20 degree micro bevels so I will check it again with both methods.

I don't think of 1300 psi as being very high stress for alloy strain.

Yeah, even if you reduce the contact area to a tenth, you only get to 13 000 psi which is still far below the elastic limit of steels, the first time I did the numbers this puzzeled me, I think it must be weaker metal and thus the yield point is way lower.

-Cliff

 

[jim_w]

It sounds like your micro-bevels are tending towards a convex edge... Is there a particular reason why you don't just convex it? I might be walking into a flaming here, so if I've missed something incredibly obvious I'm sorry!

 

[Cliff Stamp]

Is there a particular reason why you don't just convex it?

I want the angles to be consistent for the edge retention and cutting comparisons. Freehand adds too much variation in the angles which effects the results significantly.

-Cliff

 

[Cliff Stamp]

More burr information, recently I have been sharpening D2 blades and having a very difficult time getting a very sharp crisp edge. Specifically for example I had a Mel Sorg custom which recently refused to get past ~100 on thread (optimal is ~50 but that takes a lot of care and is rare, ~75 is decent), and was near impossible to remove the burr.

I wiped the edge, reset it with a 220 SiC hone, cleaned with a 1000 and then microbeveled with the medium Sharpmaker rods, deburring as Jeff describes would not eliminate the burr. I then used Carl's drastic approach, ground the edge right off, reset it again and again approached the Sharpmaker, no good.

I then switched to a fine DMT stone (which was actually fairly loaded) and by hand applied beburring strokes which cleaned the edge fine and which could then be enhanced on the Sharpmaker. I have seen similar problems with other D2 blades, they are all really hard so rolling should not be a problem.

I can see why diamonds would help because the plates are wider than the rods and they cut with less pressure but I don't see why D2 would be so prone, unless it is a machinability / strength ratio issue. Does anyone have any stats on the machinability of D2 vs S30V? I am getting more particular about edges though, I would never have even noticed this a few years ago.

Jeff have you worked a lot with D2, do you find it anything special in this regard?

-Cliff

 

[Carl64]

IIRC, my D2 Queen might have been about the same. I remember thinking the edge was finer than I expected, with everyone saying how D2 takes a terrible edge. But I also remember a little edge burr issue. At the time I got it, I had a bunch of new pretty-looking but otherwise POS Case knives, so I was probably further biased to like it.

I should compare my Queen to a Spyderco Native. They have completely different blades, but as long as I set the edge angle the same it should be fine for just comparing burrs/rolls/whatever.

 

[Jeff Clark]

I haven't intentionally examined whether burrs on D2 are best resolved using diamond hones, but on the other hand I have always ended up using a diamond hone before I was happy with the edge. The same is true with 154CM. I guess that my underlying notion was that the harder the steel I was dealing with the harder and sharper I needed my hone to be. I didn't want rounded grit that would roll around and gall the material away. I wanted a well secured grit with sharp points that would cut or peel away steel like a microscopic cutting tool. Some things that Sal wrote in the Spyderco forum set it in my mind that a diamond hone fit that bill.

I have had experience where I quit using my diamond hones prior to cutting the apex of the edge. My intent was to thin the edge using the diamonds for back beveling and then hone on a microbevel using another fine hone. I was removing enough material with my microbevel that I didn't think I needed to raise a burr with the fine diamonds. Although it looked like I did everything right the edge felt rounded over. I did't feel a burr, but the edge just didn't grab my fingerprints the way it should. After much fiddling around the problem was solved by putting a full fine edge on the blade using just the diamond hones, then just slightly improving it using ceramic rods. I never got the sense that I was removing a burr, but rather I was avoiding rounding the edge. It was as if my other hones were too complient and wrapped themselves around the hard edge carbides, like applying too much pressure on mousepad strop.

Maybe my problem was actually an unrecognized burr. My sense of the problem relating to the cutting agressiveness vs hone grit stability just leads me to use the diamonds when I get frustrated. I'll have to take another look at the issue after I get back from Ireland.

 

[Cliff Stamp]

I remember thinking the edge was finer than I expected, with everyone saying how D2 takes a terrible edge.

Yeah, obviously never used one of Dozier's knives, he doesn't have a problem obtaining a very high sharpness. It can be done, Sorg's D2 blades were also extremely sharp, no problem push cutting straight down into newprint.

It was as if my other hones were too complient and wrapped themselves around the hard edge carbides...

I can see hones wearing non-flat and having this effect, I notice a large difference when I recut an edge with a true-flat hone rather than one with a dish.

Lots of people sharpen D2 with buffers though that use really soft abrasives, the contact area is a lot higher there though.It may simply be an area factor, the DMT pads are twice as wide as the Sharpmaker hones.

-Cliff

 

[ginshun]

Great thread.

Marked for later.

 

[Jeff Clark]

For posterity I thought I would add a comment about how I tip my Sharpmaker base when I want an elevated deburring angle. As I mentioned earlier in this thread I like to reduce the honing angle on my Sharpmaker by laying a honing rod crosswise under the center of the base to provide a fulcrum and then I tip the base left and right while I hone the right and left sides of the blade. This subtracts about 5 degrees from my honing angles. I usually use the 15 degree slots in the base and get about 10 degree honing angles (20 degree included angle on the edge rather than the normal 30 degrees). My normal practice is to do this 10 degree honing until the edge feels sharp and careful visual inspection shows that I have hit the entire edge. Then I keep the same setup and do a few very light deburring strokes only this time when I tip the base to the right I hone on the right side of the edge and when I tip to the left I hone the left side. In this way I am deburring at 15 degrees plus 5 degrees (20 degrees) which is 10 degrees per side higher than my honing angle. I only do about 3 (very light) strokes per side (alternating sides right-left-right-left-right-left). Then I go back and do about 10 (very light) honing strokes per side (again alternating right/left) at my normal 10 degree angle (tip-right/hone-left etc).

For more difficult alloys I put the rods in the 20 degree slots and also use the fulcrum under the base so that I can deburr at 25 degrees per side. With a pathological alloy (I have had some knives made from old saw blades like this) I may put something like a C-size battery under the base and tilt it 20 degrees and debur at something like 40 degrees.

As I also discussed earlier, diamond hones can really help when you have a really hard alloy full of carbides like D2 or for really ductile alloys like under-hardened L6.

 

[Cougar Allen]

This is an old thread from 2005, before we created the Toolshed.

Let’s see if we can find the right forum …