Introduction: Lightweight Structural Honeycomb Panel
Welcome to my 2nd Instructable.
This instructable demonstrates how to make a very lightweight but structurally quite strong panel from 4 sheets of normal A4 paper. The panel has a honeycomb type structure internally, similar to that used in the aerospace industry to make the control surfaces, (ailerons, flaps, elevators etc.), for aircraft. Composite honeycomb panels are also used extensively in the space industry. Sometimes the honeycomb is made from aluminium but on a lot of older aircraft it was made from a material very similar to cardboard or paper. This Instructable just demonstrates one technique that can be used to make this kind of panel with normal household equipment. The panels can be scaled up to much larger and stronger ones and can be used for a variety of projects, models, home renovations etc. You can use cardboard instead of paper, coat them in plastic or resin to waterproof them etc.
Step 1: You Will Need:
4 sheets of normal A4 paper (or similar size)
Two different colours of pen
A paper shears or other device to cut paper sheets straight and precisely
Glue - It needs to be liquid enough to spread on the paper but not so liquid that it soaks through a sheet of paper
Scissors or craft knife
Draw lines on one sheet of paper. Space the lines 2.5cm apart and for every second line use the red pen. You can either draw the same lines on the second sheet of paper or photocopy the first one.
Paste a line of glue onto every second line on the first sheet of paper. I have pasted glue onto the red lines on my first sheet of paper.
Take the second sheet of paper and place it on top of the first sheet. The lines on the second sheet should face up and they should line up with the lines on the sheet below. Put a heavy book on top of the two sheets and leave them until the glue has set. In the second picture above you can see what the sheets look like when held up to the light after the glue has set. They are glued together at every second line.
Take the double sheet of paper and use your paper shears or other means to cut it up into strips about 1.5cm wide. The exact width is not too important but it is very important that every strip is the same width.
Take the first strip and paste glue onto every second line but not the same colour line that you glued the first time. This time I have put the glue onto the black lines. Place the next strip on top of the first so that it sticks to it. Keep adding glue and strips until all of the strips are glued together in a stack as in the second photo above. When they are all together make sure that the edges are all aligned and then again put them under a heavy book until the glue has set.
Once the glue is fully set you can start to open up the honeycomb. Some of the glue will have leaked and stuck the honeycomb together in places where it should not be stuck so you will need to carefully separate these spots until you have a perfect (in so far as a handmade one can be) honeycomb like in the photos above. You will need to stretch the honeycomb until it stays in the open position on its own.
Take the 3rd sheet of paper and paste glue all over it or enough for the honeycomb to cover. Place the stretched honeycomb on top of the glued sheet and press it down gently so that every bit of the honeycomb sticks to the sheet of paper beneath it. Glue up the 4th sheet of paper and place this one on top of the honeycomb. Smooth both sides out by gentle rubbing and then place some magazines or something else a little bit more flexible than a book on top and wait for the glue to set. Turn it over a couple of times during the first 20 minutes so that the glue does not all run in one direction.
When the glue is set you can trim off the excess paper from the top and bottom sheet. If you want to glue strips of paper or card on the sides to hide the honeycomb you can do that but since this is just a demo I have left the sides open. You can paint the panel, apply a waterproofing resin or just use it as it is. If you want to make a bigger panel you can in the very first steps use more than just 2 sheets of paper. You can glue 4 or 6 or 8 etc sheets together and then cut thick strips on the paper shears. Just remember to glue the alternate colour lines as you add each sheet and always use an even number. If you glue 3 or 5 sheets together then when you cut the strips and start gluing them together you will discover that you are gluing red lines to red lines and the honeycomb will not work properly when you try to open it out.
Step 10: Load Test!
This last step is just a little load test to show the Instructables community how strong 4 sheets of A4 paper can be when glued together with a honeycomb geometry. I did not test it to destruction just with 5 kilograms of books.
My test rig consists of two books to support the panel from underneath at either end and a stack of books on top of my craft knife box placed on top of the panel. I weighed the stack and it came to just over 5 kg. Quite good for 4 sheets of A4 paper I think. The panel did not bend noticeably so I am sure it can take more than this. A panel like this made out of cardboard and made a bit thicker is strong enough to stand on. ( Just of out interest every time you walk to your seat inside the cabin of a large airliner you are walking on a honeycomb composite panelled floor).
As a side note these honeycomb panels look quite good when the light shines through them. You could consider using them for non structural purposes such as a lamp shade, combined with a normal glass window as an alternative to frosted glass, a panel for internal blinds or shutters etc...