Cutting cardboard?

I've definitely noticed any blade I use gets alot more dull as I cut through cardboard. Now I use a simply Husky folding razor knife.
 
Confederate said:
My knife was a Cold Steel Night Force with 440A stainless steel, plain edge. I cut up a bunch of stuff, some of it extremely heavy. Not only did the lock hold up without a problem, the knife blade was still sharp when I finished
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You got lucky. I have the same knife, same edge, and same steel. Mine went through 3 sides of a cardborad box before taking 3 chips out of the blade (had a fresh factory edge on it too. In fact, that box was the first thing I cut with it). Needless to say I've never used it again. Thankfully I had my Vic. Swisschamp on my belt to slice through the rest of the box, plus a few more.
 
J85909266 said:
:thumbup: I love cutting up cardboard and do it any chance I get. It's a great test for edge retention, and I have sold knives that could not handle it. A good, premium steel knife should cut cardboard all day with no problems. The best part is that you can keep your knife sharp by stropping on the cardboard as you cut it up. At the end of the day, a few swipes on your preferred sharpening system or stone will have it ready for the next day, assuming you are using a quality steel and your edge is not too thin.
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its all part of our collective sickness. :D

and i typically leave edges at the factory angles, or at least try to. i don't like a real thin edge, too delicate imo.
 
Interesting thread. I never realize that cardboard contains silica, no wonder it's that punishing on knives. This makes me look at those retractable box cutters in a new light. I wonder what steel do they put on those box cutters?

Next time when I receive a cardboard box I will use it as a poor man's knife testing tool...:D
 
Cardboard does dull and edge pretty quick, but I've had good results with a finely polished edge on a Victorinox sak(even with its softish steel), loses the hair popping sharpness pretty quick but the thin blade cuts pretty well and for a long time for me with out tearing the cardboard, cutting at a 45 degree angle to the cardboard helps quit a bit as well. Some is worse than others though!
 
MORIMOTOM said:
its all part of our collective sickness. :D

and i typically leave edges at the factory angles, or at least try to. i don't like a real thin edge, too delicate imo.
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Finally, someone else that has the same opinion! None of those pansy arse, paper thin edges for me. I'll give the knife designer credit that he/she knows what they are doing. I'll take a 30° primary and a 40° secondary any day. Always worked for me.
 
As an aside on this topic - you should not use the same scissors for cutting up paper as you do for cloth. Because paper and cardboard are so abrasive, they will quickly ruin a good pair of scissors. While it is relatively easy to re-sharpen a knife, scissors rely on a precise relationship between the two cutting edges and re-sharpening can alter the way the blades contact enough to make the scissors useless for cutting fine cloth.
 
antonio_luiz said:
As an aside on this topic - you should not use the same scissors for cutting up paper as you do for cloth. Because paper and cardboard are so abrasive, they will quickly ruin a good pair of scissors. While it is relatively easy to re-sharpen a knife, scissors rely on a precise relationship between the two cutting edges and re-sharpening can alter the way the blades contact enough to make the scissors useless for cutting fine cloth.
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That's why you only sharpen one side, and to remove the burr, you just open and close the scissors a few times.

I haven't found cardboard to be much of a problem at all, but I usually only cut bits and pieces and strop on the cardboard afterwards, the only problem I have is when there are staples in them :mad:.
 
If I didn't cut cardboard with my knives, then I wouldn't have any use for them.
 
85% silica? Sounds like you're ingesting wet sand.

Cardboard shipping tubes for long objects like weatherstrip or wood trim are real fun. The thicknesses range from 1/8" to over 1/2". You don't really get to cut through them, as much as saw.

I tried it once with a BM CQC7 and it took the teflon finish right off. So much for coatings. I tried a few years later with a TiN coated blade and it was a lot easier.

Thin blades flat ground are the best - like box knives. Larger, thick swedge ground blades hang up more and get difficult to force the blade through. I've learned to avoid them - poor utililty choice, and usually mall ninja performance.
 
bchan77 said:
Interesting thread. I never realize that cardboard contains silica, no wonder it's that punishing on knives. This makes me look at those retractable box cutters in a new light. I wonder what steel do they put on those box cutters?

Next time when I receive a cardboard box I will use it as a poor man's knife testing tool...:D
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Ive been wondering what steel they use too... I can only presume that it's some form of high carbon steel based on how they like to rust. Someone here must have some info to share, I'd be keen to see some proper comparisions from the different manufacturers.

At work my D2 para is always at my side, this will make quick work of a cardboard box or two, however if there is a large amount of cardboard to be cut, I will use a retractable box cutter.

I have used retractable box cutters a lot during the course of work, and have done for the past 15 years or so. I generally use the "HD" 0.7mm x 25mm blades. For the most part I prefer Tajima blades when sharpness and precision is the main priority, when toughness is the main concern I use KDS "Blackmax" blades, these aren't quite as sharp as the Tajima out of the box, but will hold their initial edge longer and are less prone to chipping. Olfa blades are another I use occasionally, these seem similar in performance to the Tajima. I generally stay away from Stanley products these days as the quality of what shows up on our shores is questionable to say the least. "X -acto" aren't readily available down this end of the world.
FWIW I have seen more accidents with rectractable box cutters than I care to remember, there are a lot of people out there (myself included) with shorter fingers thanks to these. Buy good quality, and watch what your doing!
 
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Corrugated aka: Carboard has tons of variables so if you truly want to test your knife you should reduce these if possible. One method is just to use sections from the same (hopefully large) container.

True corrugated boxes all have 2 or more liners and 1 or 2 Mediums between them (thats alot of paper your cutting). There are other paper packaging products such as "Slick Print" (which is just extremely thick paper with a fine layer on the top and bottom) and spiral paper tubes (which are merely layers of compressed paper). Both of these are as bad on a knife edge as normal virgin corrugated paper.

A couple of the variables of true Corrugated boxes are;
  • Thickness of the paper(s) - Corrugated boxes all have different ECT (Edge Crush Test) values. The higher the ECT the thicker the outer liners of paper and the inner Flutes (waves) in the board. The ECT can be found printed in a circle or a triangle on the bottom flap of every Corrugated container.
  • Recycled fiber content - the amount of recycled fiber in the paper will drastically effect how your knife performs on the currugated. Recycled fibers are shorter but there are lots of other media involved in the recycle pipeline that can be introduced into the paper inadvertantly. Nothing is added to the pulp that makes the paper except sizing - but in recycled paper the foreign matter is the culprit of the abrasive characteristic.

Like some have mentioned I just use a boxcutter on all types of corrugated boxes or thick paper - cause you just don't know what the edge of your knife might be cutting in the paper that you can't see.
 
I have many pocket knives I have carried over the 13 years of working construction lots of cardboard around .Not always having my tools right on hand so in goes the pocket knife the best performers I have used so far have been my trusty Spyderco endura 1 ,older model S&W swat G10 model and a the first model cold steel large Voyager all plain edge .All beat the pants off all others I have used for cutting up heavy wall siding boxes and such.
P.S. CRKT knives all failed horribly.
 
My last job was as glorified janitor. My boss came up with a brilliant idea of DRP or Dumpster Reduction Program. Everything that went into the dumpster had to be reduced to the smallest size possible. I was not allowed to use a box cutter. Someone idiot got hurt using a box cutter. I tried AUS8, VG10, 154cm, S30V, D2 and all seemed to dull up quickly. Then I tried my Salt 1 with H1 steel and a serrated blade. This seemed to work a lot better. The H1 steel retained its edge for about a week in between sharpenings. I don't know if the serrations had any effect or not.
Most cut items:
Cardboard boxes
Cardboard w wax coating
plastic banding
styro foam
bubble wrap
 
MikeC said:
Yesterday was the little ones birthday, spent all afternoon cutting up cardboard from gifts, we have a big extended family on both sides. Carboard varied in thickness from flimsy to fairly thick, my knife was not razor sharp when I started but sharp none the less.

When I finished I noticed it was noticeable duller, not dull per say just not nearly as sharp as when I started. This is the first time I ever cut up this much card board, as when I was finished I had nearly filled up a 64 gallon recyle bin. The recyle bin was empty when I started. Is this typical? Does cutting a lot of cardboard dull typically dull a blade down. Again this is the first time I cut this much card board so I don't know what to expect, please do not bash me for my ignorance, I am asking to learn, not to be belittled, or berated for my lack of knowledge. Is cardboard a material which dulls a blade quicker than other cutting media per say?

Thanks
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Most paper products began life as a tree somewhere. So - - - - - cutting those cardboard boxes may not be too different than cutting wood. How much whiittling can you do without noticing a dulled knife edge?
 
I hardly ever post here but I'll throw this in. I agree that cardboard is tough on knives. Early last year I built myself a letter opener, box reducer:D, what ever needs cut around the house knife out of a small Nicholson mill file. I drew the temper to where it had a retty hard edge. I have cut up a great deal of card board in the last 8 or 9 months with it and opened a multitude of letters and junk mail. I haven't sharpened it in all that time and it still slices right through cardboard. I've used all manner of factory produced knives over the years and all of them dulled quickly but not this home made one made from file steel.

The only problem is it's not my knife anymore. If it isn't where it is supposed to be my wife starts asking where "her knife" is.

Want to find out how well any blade holds an edge quickly? Cut some manila rope with one and see how quickly it will give up it's edge. I used to help a friend manufacture piggin' strings for the rodeo cowboys made from manila rope. That's when I learned to sharpen a knife. We made a lot of strings and we sharpened a lot of knives doing it.
 
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