February 28, 2021

Custom Cardboard Box Making, by Captain Nemo

My grandfather grew up on the wrong side of the tracks, and had to make do with just the things that he had. One of the skills that he learned was building a better cardboard box. He would fit and glue boxes together, and add wooden handles to make nearly indestructible cardboard tote and storage boxes. I have some of his old boxes that are 53+ years old, and they are still strong. My father never had the knack for it, but my uncle did! He would use the cardboard like plywood and fill edges with glue to add strength. He also built specialized tote boxes for things like his Ham radio gear, and RC aircraft supplies. If you have lots of cardboard available, then this is a good way to recycle it.

Grain is Strength!

The grain of cardboard is just like the grain of wood. The side with the small holes is the end grain. Almost all boxes are built with the grain running vertical, and crossed grains on the top and bottom. Crossing the grains adds strength to the top and bottom of the box. This is the same way that plywood works. So in building up boxes, we cross the grains to add strength.

Building up a Box

Here is the basic box-building procedure: Start with an existing cardboard box that is larger than the object that you want to place into it. You will lose anywhere from a ¼” to 3/8” or more, depending on the number of plies of cardboard that you use. I normally cut the top flaps off of the box. Start by gluing the inside flaps to the outside flaps with a waterproof wood glue.

Rectangular boxes will need a filler in the “step-down” section in the bottom-center. Match the filler grain with the flaps, and glue it down. Next cut a panel that fits the entire bottom with the grain opposite of the inner flaps, and glue it down. I normally go with three plies for the bottom, but more could be added if needed. Next, cut two panels to fit the sides with the grain running opposite and glue the three edges and face of the panels to the box.

Now, cut another two panels for the ends, and glue them into place. Repeat again with the grain running opposite. It helps to use weights to hold the cardboard down while the glue cures. Next, measure the height required plus 3/8” for a lid, and trim the sides. This will leave a square edge all the way around. Fill the edge with glue and let it dry. You may have to go over the edges multiple times, since some of the end grain will suck the glue into the corrugations.

The lid for the box can be made from four to five plies of cardboard. For a four-ply lid, cut one panel the size of the box, and three panels that will fit within the top of the box. For five, cut a second top panel. Make sure that the panels’ grains cross. Start by gluing the three smaller panels together, and then the top panels together. Next, align and glue the smaller panels to the top so that the small panels will fit inset into the box, and the edges of the top panels will be flush with the box sides. Fill the edges with glue.

Give the box and lid a few days to dry. You may then sand the rough edges of the box and lid with 220 grit sandpaper. You can now paint and decorate the outside of the box. Polyurethane spar varnish also works well to harden the box, and give water resistance.

Getting Creative

You are only limited by your creativity in what you can make. Dividers, supports, and handles can turn your basic reinforced box into something really specialized and quite useful.

Ninety-degree angles can be made by removing the web between peaks of the corrugations, adding glue, and folding. Your only limitation is that bends must be made at corrugation spacing. Curves may be made by slitting the web at one corrugation, moving to the next and slitting, and so on until you have enough to make the curve. Slitting should be done on the inside of the curve. Then glue the piece down, and after that fill the edge with a bead of glue. With the glue on the edge, you only need enough to seal the edge, not fill the entire depth of the hole. Sometimes though, the hole will suck up glue like you wouldn’t believe! Once it is in the proper shape, reinforced paper tape may be used to reinforce the slit side. This is the same method used in woodworking to produce curves in sheet material.

A Sample Box-Building Project

The accomanying photos show a divider for a 250 ML Erlenmeyer laboratory flask. In the first picture, you can see the built saddle for the neck of the flask, and the layout. In the second picture, the full construction. You can see the material removal for the 90 degree bend on the right. The other 90 bend is a butt joint that is glued and reinforced with tape. While this is just a demo, it could be used in a box to keep the glassware separated to prevent breakage.

I’m glad that I built this project at the bunker, as I learned that I am missing an important layout tool in my bunker workshop…a bow compass! Remember: You can’t anticipate everything! Another good reason to “live your preps”. It helps find your mistakes. During SHTF, this would have cost me some silver, instead of worthless fiat cash now!

My Early ProjectS: Weapons Cleaning Gear

In the next photo is my bunker weapons cleaning tote. This has lasted 10 years so far, and it’s still strong. The inside is varnished and seems to resist the solvents and oils well. This was one of my first projects.

And here’s another project. The weapons cleaning accessory spares box. This was built for the arms supply cabinet.

Those are just a few examples.

So, as you can see, you’re only limited by your creativity with cardboard. Use your cardboard instead of throwing it away.

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