Introduction: Geared Christmas Card

About: Recently finished a Ph.D. in Mechanical Engineering. Still love creating in my spare time

A card cut from poster board with a moving rack and pinion gear inside. When the card opens the gears move, and reveal images in four windows.

Step 1: Materials

To create this card you will need:

- Poster (Bristol) Board
- White Glue
- A Printer
- The attached PDF
- An Hobby Knife (X-acto knife)
- A Cutting Surface

It would be beneficial to use something thicker for the gear layer, but it will still work using poster board.

Also, if you have access to a CNC method of cutting the paper or wish to alter the plans, I have attached a .dwg of the file. If you need another common format (.stl .dxf etc.) let me know and I should be able to make it.

Step 2: Mount the Design

Start by printing out the pattern attached and removing most of the extra paper. Cut a piece of the poster board and tape it in place.

Step 3: Start Cutting

For cutting the pattern, it is best to start in the middle of a given part. This is because if you cut the part out before removing the details, the pattern will need to be taped to the part. This can leave unwanted tape marks and the patter might not be in exactly the same place.

To cut the gear teeth, start by cutting the circular portions only(see image below) then cut along a connecting lines to get the final shape.

If the part doesn't come out easily, don't force it, doing so will only create rough edges. Flip the part over and score along the lines, the part then should basically fall free.

The gear should be able to be placed around the smaller circular piece and rotate freely, this may require some trimming.

Step 4: Glue the Gear Layer to the Base

Start by gluing the outer portion of the gear layer the the bottom layer (the single blank rectangle). I find it easiest to just spread the glue over the back side using my finger, messy but simple. There are other ways such as a paint brush to do it neater.

Once the fist section is dry (it shouldn't take long) apply glue to the smaller circle and place it on the bottom layer in the middle of the larger circle. It may help to place the gear over to center it before it is dry.

The two gears should have no glue on them.

Step 5: Glue on the Top Layer

After you have created any details you want as outlined in the last step, apply glue to the outer gear layer and gear axle (circle in the middle). Be careful not to use so much glue that it will squish out of the sides and glue the gears in place.

It is important not to get glue in the gears because if you do, it could interfere with the gear movement or glue them in place. Alternately, if the glue isn't close enough to the edges the mechanism will slip.

For this step it is best to leave the rack out, it can be easily inserted later.

Once the glue is evenly applied, press on the top layer. Be careful that the gear doesn't slip out of place and get stuck in the glue. If a little glue did get stick on the gear, you should be able to loosen it with the knife.

Step 6: Attach the Rack

Slip the rack into place. If it sticks, try turning the gear using a dull knife or similar to help it into place.
Once It is in place, fold where the dotted lines were on the pattern and put glue on the backside of that section.
Close the front cover, again along where the dotted line was, and hold it in place until the glue dries.
This should attach the rack to the front cover so that when the card opens, the gear will rotate.

If the rack is too weak to turn the gear when closed, it can be reinforced with an extra piece of poster board.

Step 7: Customize

This step is where you can really make it your own.

To add the details in the gear, I cut out some shapes and filled the holes with another colour, fastened by tape on the back. This makes it so that it lies in the same layer, not interfering with the operation. I also did the same thing for the cover, rather than just glue on the parts.

To embed another colour of poster board, start by layering an outline of the shape to be cut on top, the part to cut the shape out of, and the replacing colour on the bottom. Next, use the knife to perforate an outline of the shape, pressing firmly enough to go through all layers, but not so hard it damages the knife. Separate the layers and cut along the perforations in the poster board. You should now have a hole in one part and a matching shape in the replacement colour.

Cut a piece of paper that will fit over the back of the design, apply glue, and attach everything in place.

If you do create the card, or a variant, leave a picture in the comments. It's always interesting to see what other people do.

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