Normal after cardboard?

[ShawnKirkpatrick]

I had a cardboard box that needed to be broke down and I had my yojimbo 2 on me. So I started cutting the cardboard (I cut across the flutes as Evil D says they are called and is the hardest way) it was kinda a test for the yojimbo I wanted to see. After 175 cuts this is what I'm left with.

It would still slice newspaper pretty good. But I could tell there was imperfections in the edge. I'm still trying to learn this edge stuff and am trying to see what is normal and what isn't. Thanks for the input guys!

[MattM68]

Factory edge?

[ShawnKirkpatrick]

Factory edge?

No, I reprofiled to 30° with a 40°MB

[MattM68]

That seems odd then. But if it's still slicing newspaper then that's pretty darn good! It's just a little hard to see exactly what's going on in the pictures. What I've notice from cutting a lot of cardboard is that the edge seems to round off, but I've never seen edge damage unless I hit a staple. After dulling a knife from cardboard I can bring it back to hair popping sharp within 5 minutes usually.

A 30 degree edge with a 40 MB is pretty standard, so I don't think that would be a problem. My Yojimbo is 30 degrees with no MB, and I've never had a problem with cardboard. Good luck!

[paladin]

I've never experienced that kind of deformation that was that noticeable breaking down boxes...but then again 175 cuts across the grain is quite a bit and I can't recall ever cutting that much at one time without a touch up in between.

At first blush I was thinking along the same lines as Matt -- that is, brittle stressed factory edge.

But since that's ruled out...do you think you might have had a bit of a burr or wire edge that wasn't fully erased with the MicroBeveling?

Then there's the composition of the cardboard itself, which can vary widely. A lot of cardboard is recycled and contains a lot of grit / grime.

Plus, what you have on your lap looks pretty thick and heavy duty in it's own right, grit notwithstanding.

So....IMHO, all things considered-- overall not that bad.

And what I think is even more important to consider here is: How LONG will it take you to erase that damage on the SharpMaker?

Because, after all, we've all been where you're at now at one time or another.

[Evil D]

Corrugated board is nasty stuff. Not only is the paper itself filled with all sorts of impurities like clay but the starch glue that holds the sheets together dries rock hard, and you're cutting through that glue along with the paper so it's more than just cutting through paper. Cutting against the flutes just forces you to cut through more sheets of paper and more blue than if you were with the flutes. Beyond all that there are a slew of different grades of "cardboard", ranging from the thickness/weight of the sheets of paper being glued together to how large the flutes are, and then there are double wall sheets and so on and so on, depending on what the final box will be used for. I used to make boxes for a company that shipped electric motors that were about the size of a basketball, and those boxes were so beefy a grown man could stand on top of one and it wouldn't crush.

Anyway, is that normal? It depends on the box you cut, what kind of crap you ran through in the box, and how the knife was sharpened. I've seen worse that's for sure. The pic of the board you were cutting looks like a pretty stout box, that's double wall and the paper is pretty heavy weight stuff so I wouldn't be surprised at all if you got some chipping and rolling from that. There are some types of corrugated board out there that you can cut all day with a butter knife, the paper used is all such a light weight that a typical steel like S30V will cut it practically forever. Your typical retail box is usually this kind of flimsy light weight box that isn't meant to do much more than hold X amount of a product together for shipping purposes.

Fun fact, next time you go to McDonalds, order a Big Mac. The little box it comes in is actually corrugated board. The flutes in that stuff is teeny tiny (at least it used to be, been a while since I had a Big Mac lol).

[ShawnKirkpatrick]

Thanks for all the advice guys. It is possible that maybe I didn't remove all the burr. I thought I was getting good at removing them, guess I need to focus more on that. But I thought it seemed like stout cardboard, and maybe I shouldn't have cut against the flutes the whole time. I spent about 5-10 minutes on the SM and got it slicing newspaper again but when shining a light on the edge I can still see some shiny spots. Any other advise guys?

[Water Bug]

Thanks for all the advice guys. It is possible that maybe I didn't remove all the burr. I thought I was getting good at removing them, guess I need to focus more on that. But I thought it seemed like stout cardboard, and maybe I shouldn't have cut against the flutes the whole time. I spent about 5-10 minutes on the SM and got it slicing newspaper again but when shining a light on the edge I can still see some shiny spots. Any other advise guys?

I've found trying to totally remove flat spots (the shiny spots) along the edge can take time, depending on the extent of the damage...

What I do for those more persistent flat spots is to concentrate only on that particular area using the corners of the Spyderco Tri-Angle Stones on my Spyderci Tri-Angle Sharpmaker. I'll start with the corners of the Brown Tri-Angle Stone and check the area... if it's still shiny, I'll either keep trying with the Brown Stone or switch over to the corners of the Diamond Tri-Angle Stone. Once I finally get rid of the flat spot(s), I'll then run the entire length of the edge along the corners to even out the edge then move to the flats of the stones and then go through the different grits (Diamond to Brown to White... i.e., perform your normal sharpening process). Again, this'll take a little more time, but you get a nice edge with no flat spots reflecting back at you.

Hope this helps.

[Brock O Lee]

Thanks for all the advice guys. It is possible that maybe I didn't remove all the burr. I thought I was getting good at removing them, guess I need to focus more on that. But I thought it seemed like stout cardboard, and maybe I shouldn't have cut against the flutes the whole time. I spent about 5-10 minutes on the SM and got it slicing newspaper again but when shining a light on the edge I can still see some shiny spots. Any other advise guys?

I assume you did not cut off the old damaged edge as a first step of sharpening? This makes a huge difference in edge retention in my experience. It is easy to build a seemingly perfect edge by sharpening the old damaged edge, but it will show damage not long after you put it to work. This happens because the underlying steel is still fatigued. I have seen this time and again, especially on my wife's kitchen knives. They see some rough use, and I often have to resharpen rolled edges. If I am lazy and do not cut off the old edge before I sharpen them, they will show damage much quicker than if I do.

Credit to Cliff for this one: remove all damaged and stressed steel from the edge by doing 2-3 light slices perpendicular into a SM stone, like you are trying to cut the stone in half. You have now completely cut off the old edge, and the whole edge will reflect light. You now have fresh unstressed steel to build an edge on.

[JAfromMN]

Cardboard can have all kinds of sand and **** in it

I've done that myself

[ShawnKirkpatrick]

So is this normal for this kind of work? It's seems like the last time I broke down a box I used my paramilitary 2 and cut way more cardboard and didn't seem to have as much deformations in the edge.