The science of cutting cardboard: Box cutter? Rotary cutter? Scissors? Ceramic? Serrated? Nonstick? Electric?

Factual Questions
1

My middling physics education did not prepare me for this predicament of adult life: What is the best tool for cutting up corrugated cardboard boxes, and more importantly, why?

Let’s start with your humble box-cutter. You know the kind, cheap plastic thing with scary little blade segments that always threaten to come apart and rip up your garbage bag (or your kids or pets…):

OK, they work, but dull quickly (hence the disposable segments). Why? Something something plant fiber something something cellulose something silica…? I have no idea.

Then you have the ones with ceramic blades:

What’s so special about ceramic for this usage? It’s harder than steel? How does hardness affect cutting ability, physically?

Then you have the samurai letter openers:

Made by the legendary swordsmiths of Japan, then given a serrated edge and teflon-coated. Do the serrations actually help? Why don’t all box cutters have them? Does the coating matter?

That same company also makes special cardboard scissors:

Does that shape confer some particular mechanical advantage against corrugated cardboard?

Speaking of scissors, apparently you can also get electric scissors, though don’t so much cut with and open-and-close motion as much as “sawing” through at a high rate of vibration:

Is that any better or worse than having longer scissor handles/levers? Is there an optimum rate of vibration that can specifically disintegrate cardboard fibers?

But then there’s also the rotary kind, basically a weak rotary cutter with a guard:

Which mechanical motion — a vibrating saw or a rotational cutting disc — works better?

And then there’s the “just for cardboard” premium kind that’s double the price of the other electrics:

That uses a standard utility knife blade and again vibrates it like a saw. It can accept both serrated and straight blades.

Soooo many different kinds. What’s the science behind all this? Is there anyone who’s attempted a systematic study on them to understand (and optimize) all the physical and mechanical forces involved? Are some better for certain kinds of cardboard than others? Is there some curve (or spider/radar graph) between sharpness, durability, ease of use, safety, etc.?

2

With ordinary scissors, the handles (and hence your hands) would be directly in the plane of the material being cut. When the material being cut is flimsy paper or cloth, that’s no problem: It’ll just fold out of the way of your hand. But for stiff cardboard, you want you hand to be all the way on the outside of the plane.

3

Just how much cardboard do you need to cut and how much do you want to invest in this? Because some of the products you’ve shown cost $20-40.

4

It’s all according to what kind of cardboard you have. I can rip or smash a cereal box. A packing carton, I can fold flat.

Tag board you’ll need a knife. Get the simplest box cutter you can find(I personally don’t like snap off blade ones, seem flimsy and feel slick in my hand). A Stanley box cutter that unscrews for a new blade are great.

Scissors not so good unless it’s a quick cut of poster board.

Any small cuts, say of cardstock, an Xacto is good.

I don’t think power tools are necessary unless you’re cutting 20 layers at a time.

5

I’ve been in a cardboard-cutting intensive business for more than twenty years. We often fill a dumpster-sized recycling bin with broken down boxes in less than a week. There’s no beating the disposable plastic cutter in your first pic for affordability and effectiveness.

6

Meanwhile, I’ve worked at places that receive enough packages that they had a dedicated machine to crush the cardboard into bales roughly 4’ x 3’ x 3’, so really no one was bothering to cut any up.

7

We have a bunch of the serrated cardboard knives and they work really well if you value precision over speed. If you are constructing things out of cardboard, these are great. If you just need to cut down some boxes so they fit in the recycle bin, one of the other options is going to be faster.

As for the electric cutter/rotary things, I’ve never used one, but the Project Farm guy really liked the one from Skil. It’s even show up in other videos when he was cutting paper or cardboard strips.

8

I have what you call the “samurai” style. It works pretty well, made for cardboard.

A paper shredder works wonders, but you probably want at least an 18-sheet model if you don’t want to burn it out or spend a lot of time unclogging it.

9

For breaking down cardboard for the recycling bin I use a standard retractable utility knife like a Stanley. Depending on the strength of the cardboard I can slice through two or three layers at a time.

10

I use a utility knife like your first example, except a higher-quality metal one from a hardware store rather than the cheap plastic kind you show. And I have a large pack of replacement blades for it.

But mostly I am just flattening cardboard boxes for recycling, so I mainly am cutting thru the tape over bottom seams on the boxes – not actually cutting cardboard at all much.

11

I keep one of the plastic retractable Stanley ones in the kitchen drawer, and change the blade frequently.

12

Just bought a new house, so we are ordering all kinds of stuff. We are about done so I’ll just keep using a utility knife that has replaceable blade.

It’s odd, I have a nice folding knife that I keep very sharp, but the utility knife works better.

13

How about a handheld drywall saw - one of the ones with double blades that looks like a nasty old dagger? I watched my neighbor saw apart a thick corrugated sheet into pieces in less than a minute.

14

I prefer the folding box cutters to the retractable ones. The thumb button on the retractable ones always seems to get sticky and who needs that in their lives? The foldable ones also don’t need a tool to change the blade, and the parts don’t threaten to fall out when you unscrew the case.

I was recently turned onto serrated box cutter blades. That’s a nice twist, they do a good job on cutting rope/twine and slicing cardboard.

I would expect ceramic to be a terrible choice. Yes, very hard and sharp, won’t dull easily, but can snap. Edited to note that these do have replacement blades, $5 a piece on Amazon! You can get metal blades for 10 cents each.

15

I use that grey metal “Stanley” tool and change the blades frequently. They store 4 or 5 extra ones inside the handle. When you cut, keep the line you will cut along a little to your right side so that you can pull toward your self all the way down and go past the edge without getting close to your body. It is helpful to place the box on a surface like a workbench or table to stabilize it. as you cut have an idea of the shape of the bottom of your garbage can or recycle bin so that they will stack neatly inside and not use up all the space in there.

If the recycle bin or garbage can is full stack them up and run a line of tape around them to make a neat bundle and place on top of the bin, the collection people will

16

We bought this one just last week. Works well.

17

Exactly this. I just got off the train from a four-leg four-day journey from Boston to Oakland with a stack of framed artwork that I fabricated a crate for out of corrugated cardboard and strapping tape. I used to build architectural models out of corrugated cardboard (and other materials), a slightly serrated blade allows you to readily score the material for folding without cutting all the way through. When absolute precision isn’t required (as for my crate) it’s easy enough to follow pencil lines without using a steel straight edge.

18

I cut a load of different mediums. The Stanley (or variations) for corrugated cardboard. A scalpel for thin cardboard and paper. Cheap (ie disposable) scissors for expanded foam, a hot knife for polystyrene. A hacksaw for PVC piping.

I make large wearable puppets for light entertainment… halloween is coming and I am building a dragon and bird for my kids.

So knowing what best cuts what is quite imortant to me. Foam is a bastard, it blunts everything.

19

The plexiglass test was interesting. I tried cutting plexiglass (to replace broken birdfeeder panel) and it did not go well. I don’t do that enough to justify one of these electric things, but I could see someone who cuts a lot (cosplay? model train?) it would make sense to get one.

Brian

20

Personally, I’d venture to guess that a water jet cutter would be the most easy and effective, if you had one available, and weren’t worried about accidentally cutting off your limbs or fingers while working with it.