How to Make an Egg Carton Cutter

We're a team of 3 students Industrial Product Design. This instructable is the collection of our hard work and research during this semester. The assignment this semester, was to make a machine that could help children with a mental disability with their arts and crafts. The machines should enable the children to make things on their own. During the semester we also did some user test on a test group of about 7 children. These tests helped us a lot during the designing process, since none of us had any experience with this user group. To narrow down the possibilities, we had to choose an arts and crafts material our machine should interact with.

Our material was egg carton.

At first we were quite unsure what to do with this unusual material. After browsing some arts and crafts books, we noticed that a lot of recipies used the individual pieces of the egg cartons, as well as strips of them. So our first idea was a mould to hold the egg carton and let the children punch the pieces out with a needle. After a first test, we noticed that these 6-year olds lost their interest pretty quickle because this was a tedious task.

The second idea was much better. We came up with a saw table. We mounted a plexi glass cover around the saw to protect the children and help them position the saw so you always get evenly cut stripes of egg carton. Being able to look through the front of the machine also helps the user position his cardboard and gives the children the possibility to be more independant, now that they can see what they're doing.

In the end the machine had some great results during the tests and the children seemed to really enjoy themselves when using it. We hope you have the same results after following our instructable. :)

Materials

In the image above (Image 1) you'll see the parts and their measurements. The materials used in this build are plywood (18mm), plexiglass (5mm) and a piece of natural wood for the handle.

1. Frontplate (390mm x 310mm, PLYWOOD) : you'll need to cut this part out twice, because you'll need it for the front- and backplate. Also cut an angle at the end of these plates, both ends should be cut at a 20° angle. (see Image 2)

2. Plexi frontcovers (390mm x 70mm, PLEXIGLASS): these parts also have to be cut out twice. The little pieces you have to cut out on the top will form a rest for the saw when everything is assembled. The covers will keep the egg cartons in place while they're being cut and will protect the user from the saw.

3. Bottom guide (56mm x 310mm, PLYWOOD): this will be the bottom guide for the egg cartons.

4 & 5. Top guide (56mm x 240mm and 56mm x 66mm, PLYWOOD): these 2 parts will be the top guide for the egg cartons. The only difference from the bottom guide is the space left between the 2 parts, that's because the saw has to be able to move through that guide.

6. Plexi topcover (150mm x 310mm, PLEXIGLASS): this will be the cover for the top of the machine.

7. Sideplates (400mm x 395mm, PLYWOOD): You will have to make this part twice. There are 2 protrutions on the bottom of these parts, these will hold the front- and backplate.

8. Handle

9. Sawblade: look for an old iron sawblade of buy one in your local DIY shop.

10. bearings (2): old bearings from a skateboard or bike will do fine.

11. Anti-slip knobs

12. screws (inner Ø2.1mm and outer Ø3.6mm, 50mm length)

13. bolt and nut (M5 x 25): you'll need these to connect the sawblade to the handle

Tools

1. Electric drill + drill bits : this is used to drill holes for the screws and drill in the screws.

2. Band saw/ Jigsaw: you'll need a saw to cut the plywood and plexi parts, make sure you use the right blades for the saw, blades for plastic are usually different from blades for wood.

3. General equipment: pencil, measuring tools, sanding paper

Take the frontplate and draw the slit on it with pencil, you can check image 1 for the right measurements. Once you've drawn the slit in with pencil, you drill a hole in 1 end of the slit and saw the rest out with a jigsaw. If your cut was a little uneven or you didn't go wide enough, you can always use some sanding paper to fix some rough spots.

Before you start drilling holes, you should draw where both guides will be placed on the frontplate. Do this on both the front and back of the plate, these will be your reference where you'll have to drill some holes and use your screws. (use the measurements on Image 1)

Fixing the front guide to the plate isn't that hard, since this one borders at the bottom of the frontplate. (Image 3) The 2 parts of the top guide will be a bit harder, but use your pencil references to position everything correctly and use a glue clamp to make sure nothing moves around while you start drilling and screwing.

Once you've fixed the guides to the frontplate, it's time to mount the frontplate on the 2 sideplates. During this step, you might need some help from a friend to hold everything together while you drill holes and screw screws.

Once the frontplate with the guides is connected to the sides, you can screw the plexi glass covers to the front. When you do this, make sure the little pieces you've sawn out of the plexi glass are on top of the build and are pointed towards each other. This gap will create a rest for the sawhandle.

You can always do this step before you fix the frontplate to the sides if this is easier. But you'll have to take 1 cover off when you connect the sides and front, because the plexi glass will block your drill. (Image 2)

To make the saw, you can draw a handle shape like the one in Image 1 on a piece of natural wood. We suggest you using natural wood because it can be sanded down easily and without splinters. cut it out with a jigsaw. To cut out the inner part of the handle, you drill a hole in that part and use the hole as a starting point for your jigsaw. Make sure you leave an area (20mmx30mm) where you can drill 2 holes to attach the saw blade to.

Once you've cut out the handle, you can drill 2 holes 25mm apart from each other. You can then do the same for the saw blade, but make sure you use a very strong drillbit. The metal of a metal saw is very hardened and could break your tools if you don't have the right drillbit.

Once all the holes are drilled, you can attach the saw to the handle, using 2 bolts and nuts. Put roundels between the bolt and nut and the wood to ensure a stong connection. (Image 2)

Now you can put the sawblade between the 2 plexi front covers and the slit in the front plate. The saw should be coming out the other end of the machine, where you can attach a stop to the blade, so you can't take it out of the machine. (Image 3&4)

On the end of the saw blade should be another hole, here you can attach a bearing on each side of the blade with a bolt and screw. Also don't forget the roundels. (Image 5)

All that's left to do now is to close of the back with the backplate. This will go a little bit easier since the sides are already standing. And when the plexi top cover is screwed on, you can finally start sawing away. (Image 1)

To increase stability, you can put some plastic anti-slip knobs on the bottom of the machine. These will also make sure the machine doesn't slide around while you're using it.

Optional: if you're making this for children, and you want to make this machine foolproof, you can make a stop next to the saw where the egg carton will stop. If this stop is 18mm (normally the thickness of your plywood), the egg carton will always be cut on the correct line. (Image 2)

In the end we made a simple, but very effective solution. The weight on the end of the saw and the downward cutting motion, make sure the cardboard is cut fast and smoothly. The plexiglass on the front also gives the user more assurance to whether the cut is going to be right or not.

The machine is also very easy to clean, all of the leftover carton will collect on the bottom guide or will fall down in the machine and on the table.