Possible wire edge problems?

Nosetotail

Nosetotail

Joined
Jun 10, 2007
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398
I've seen mention several references of a persistent wire edge and I am wondering if this is talking about a burr or just an edge that is ready to fold over. I put a 25 to 27 degree back bevel on my knife and I sharpened the primary bevel to 33 to 35 degrees inclusive. I wouldn't call it a microbevel as it is quite visible. It's a zdp blade and I am getting it quite sharp, somewhere between shaving and hair popping sharp. I'm not stropping as at my skill level that seems to do more harm than good (I sharpen strictly with a guided sharpener). I finish with several alternating strokes with my dmt ultra fine stone to remove any burr.

I frequently have to cut what's normally called mule tape or "flat strap". I believe it is braided nylon and it is about 1/8" thick by 3/4 or 1" wide. Also, often but not always the flat strap is some what coated in silt and some dirt dirty. I get an effortless aggresive cut on the first swipe, but often by the third swipe, I have to bear down and then after that I have a burr running down one edge. I understand that nylon material isn't easy to cut and given that I can expect some dulling, but what I'm concerned about is how quickly this happens and the fact that I get a burr. Is this normal dulling with this type of material and zdp?

Could this be a product of how I'm sharpening, or should I be concerned that I may have a bad heat treated blade?
 
Kind of sounds like your not getting rid of the burr. Try raiseing the angle a degree or two for the very last few sharpening strokes.
 
I raised the angle about a degree and took about twenty ultra light alternating strokes, and same story. Could I be taking too light of strokes at the end.
 
Perhaps you aren't getting the wire edge off.

High end steel isn't always the solution to cutting. Coarse and especially gritty materials can damage the best of blades, and a thin edge angle will show that damage quickly.

Go ahead and sharpen your knife the way you normally do, then use it on ordinary materials. For example, try it on food preparation, try it cutting heavy cardbord, try it whittling or shaving twigs.

If it holds up to these, it's fine, and the problem is, you need a more obtuse angle for that mule tape.
 
20 strokes would be too many to remove a burr with a diamond hone, and you could be creating a new burr at the higher angle. It will only take 1 or two strokes alternating sides. Keep them very light strokes. You can raise the angle much more than just 1 degree if you like maybe try 5 degrees just make sure you stop as soon as the burr is gone.
 
Esav Benyamin said:
Perhaps you aren't getting the wire edge off.

High end steel isn't always the solution to cutting. Coarse and especially gritty materials can damage the best of blades, and a thin edge angle will show that damage quickly.

Go ahead and sharpen your knife the way you normally do, then use it on ordinary materials. For example, try it on food preparation, try it cutting heavy cardbord, try it whittling or shaving twigs.

If it holds up to these, it's fine, and the problem is, you need a more obtuse angle for that mule tape.
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Just so I'm clear on a couple of things, is 33 to 35 a thin angle, and if so is it real thin or just a bit thin. What would be a good general obtuse angle?

Also, the last test I did was with a clean, almost new piece of mule tape, and it feels somewhat silky, but it still created a burr. Are you saying the nylon in general is a coarse or gritty material? I have seen it several times on here that it is hard on a knife, but does that mean it will raise a burr?
 
33 to 35 is not real thin. For example, the Sharpmaker gives you a choice between 30 and 40, so you fall into that range. For most people's daily utility use, even less than 30 degrees is good, especially with decent steel prperly heat treated.

I think I misunderstood, that your problem was primarily with dirty rope, rather than simply nylon. In either case, coarse material by itself will not raise a burr or wire edge, it will simply damage the wire edge you might already have (break it or roll it).
 
Well I wasn't sure until I found a pretty clean peace I had at the house and tried to cut it. I get about two cuts before I have problems and then after about ten cuts it's all over with. I might as well try chewing through it. Interestingly though is that we have a couple of brands at work and its the silkiest finest thread stuff that is the hardest on my blade, compounded of course by the dirt and silt.
 
knifenut1013 said:
you should try polishing the edge
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I'm not sure how much finer I have to go to consider it polished. I have a well seasoned dmt 1200 grit stone that I finish with and there is a dull light glinting off of the bevel. I've been thinking about ordering their ceramic stone, but I figured that the ex fine was fine enough. I am in the process of making up a strop and my own slide rod that I'm thinking about glueing sandpaper to, but I just assumed that the ex fine was adequate.
 
If you're cutting a strap that's flush up against something from underneath, make sure you pull on it to get the full blade under the strap at 90 deg. If you cut at an angle, it will roll the edge. Sometimes when doing a quick cut, the blade edge angle to cut is less than 90 deg. This is when edge rolling happens. Not sure if this might be your problem. I let a coworker use one of my benchmade knives years ago and he did this and chipped the blade. Taught me a lesson I still haven't forgotten. Now only two or three people touch my knives.
 
I raised the angle about a degree and took about twenty ultra light alternating strokes, and same story. Could I be taking too light of strokes at the end.
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In my experience, reliably removing a wire edge requires 3 to 5 degrees additional bevel per side to remove a wire edge. Trying for less, with either strop or stone, will usually just sharpen the wire/false edge - making it even more floppy/fragile/unreliable.

Some combinations of steel and heat treatment seem particularly prone to producing a wire edge and careful attention to remove it. My Buck/Strider Tarani folder with ATS34 absolutely required a 5 degrees microbevel on each side of the edge to cleanly cut the wire edge stabilize the final edge.

Hope this helps!
 
Cliff Stamp said:
Go significantly more coarse with your sharpening, as in x-coarse DMT or similar.

-Cliff
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Funny you say that as that's what I started doing, but then I read the stropping kung fu thread and I got into seeing how fine an edge I could get. I think I'll go back to my x-coarse edge and give it a go.
 
mwb said:
If you're cutting a strap that's flush up against something from underneath, make sure you pull on it to get the full blade under the strap at 90 deg. If you cut at an angle, it will roll the edge. Sometimes when doing a quick cut, the blade edge angle to cut is less than 90 deg. This is when edge rolling happens. Not sure if this might be your problem. I let a coworker use one of my benchmade knives years ago and he did this and chipped the blade. Taught me a lesson I still haven't forgotten. Now only two or three people touch my knives.
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Most often I cut the strap by folding it over my blade and grasping the two "ends" with one hand holding it taught, then pulling my knife through making a cut with one swipe. I will pay attention to whether I am cutting at an angle when ever I'm cutting a piece that is layed out.
 
gud4u said:
In my experience, reliably removing a wire edge requires 3 to 5 degrees additional bevel per side to remove a wire edge. Trying for less, with either strop or stone, will usually just sharpen the wire/false edge - making it even more floppy/fragile/unreliable.

Some combinations of steel and heat treatment seem particularly prone to producing a wire edge and careful attention to remove it. My Buck/Strider Tarani folder with ATS34 absolutely required a 5 degrees microbevel on each side of the edge to cleanly cut the wire edge stabilize the final edge.

Hope this helps!
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It's funny that you mention the ats34 as I had a persistant problem with it also. I chalked it up to just being stainless steel. When I lost my last knife, I tried the zdp for it's uber classification. I knew it wasn't necessarily as good as it is touted, and was aware that I may run into sharpening problems, but I wanted to try it, and deal with whatever problems I run into. I geuss this is one of them.

My biggest issue here is that I can't fathom the wire edge. I can picture a burr being on one side or the other, but I can't picture how a wire edge can levitate perfectly between the two opposing angles. I use my guided aligner with extreme care not alowing my guide rod to float period, and I feel I have the straightest edges I can possibly get. As a result, I am very tentative about going over my angle very much and possibly rounding my edge. I'm new at stropping and everything I have seen tutorial wise stresses going under the angle and allowing the leather to flex over the edge. Also, I haven't gotten around to loading my leather and I'm not sure if I'm just spinning my wheels trying to use unloaded leather.
 
It takes a certain amount of force of the blade edge into the stone surface to cause abrasion. For very tough blade steel, as the edge is thinned to a perfect apex during shapening, the force required for abrasion can exceed the lateral stiffness of the thinning edge. At that point the edge deflects away from the stone and is not ground away. This forms a thin flap or leaf of steel along the edge which gets longer as sharpening continues, but is difficult to remove.

You can imagine that very thin bevel angles would encourage this and that steep angles would discourage. Thus a steepened micro bevel is a good idea.
 
Thanks, I need that. I could picture what it looked like, just not how it was possible.

So I just official stropped with white compound on the rough nap side, and of course I didn't do a good job. The edge went from shaving fine hair sharp to just shaving sharp, however I'm thinking that this should indicate that I removed the wire edge. I tried again on the mule tape, and same story, however I didn't notice as much of a burr left over, but the ultra polished edge just didn't cut it at all, maybe one or two slices.

I think I will try the ex coarse stone again, however this just poses the wire edge delima again. I wonder how I should finish after the excoarse stone to ensure I don't have one. Perhaps I should raise it like you suggest for one swipe. I'm just worried that the ex coarse stone is too aggressive for this. Perhaps my medium or fine stone will work?
 
Perhaps you could get a different tool of some sort for cutting the mule tape, since you need to do this particular job so often. Perhaps some sort of heavy duty scissor or snipper?
 
We have square tip crome vanaduim carbon steel wood handle knives at the ready. Probably the sharpest thing around short of a straight razor and I started touching mine up with my aligner so they are extra specially sharp. I just want my knife to be the uber knife that I can whip out whenever there is an oppurtunity and still have confidence it isn't going to start struggling. I shopped for a decent utility blade and spent a few hours rebevelling it to my liking.

I geuss perhaps I have unrealistic expectations for a stainless offering.

The thing is that we work on the fly and if I have to walk even five feet to grab another knife out of the truck, I have wasted steps and time. I am often in a manhole and I don't want to climb out of the hole or ask someone to fetch me a knife just to make a cut with something else to preserve my precious fragile knife, and I'm not inclined to carry a fixed blade with me every where I go. It isn't a problem cutting the material, just more of a nuisance having to touch up my edge everytime I come in contact with something like the mule tape. It certainly isn't consistant with the often laid claims that ones zdp blade hasn't needed sharpening for weeks. I don't expect miracles, I just wanted a noticeable difference, and alas I still haven't ruled out that it may just be user error.
 
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