© Rob Ives 2011
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Cam / Cam Mechanism
This is a proposed mechanism for the forthcoming Dodo project. The Dodo model will demonstate the typical flight path of now extinct bird. A quick burst of wing flapping and a short moment in the air. To acheive this effect the mechanism uses two different cams, a multi-lobed cam to drive the wings and an offset circle cam to lift the body. I've made the mechanism available for members to download and experiment with.
Members can download the file at the bottom of this post.
You will need a pair of scissors, some glue and a glue spreader. The best type of glue to use is white school glue (PVA.)
Print out the parts sheets onto ordinary thin card. Coloured card works well and makes for an attractive, colourful model. Leave the ink to dry completely before continuing.
Before cutting anything out, score along all the dotted lines. This job is easier to do on full sheets of paper.
Dashed lines are hill folds, dotted lines are valley folds. Cut along the solid lines. Grey areas show where to glue.
Glue together the three cams to make double thickness parts. Make sure that the tabs on each of the cams aren’t glued.
Glue together the cam shaft. Slide the three cams into place. Use the picture for the correct arrangement and alignment. Glue the cams to the grey areas on the cam shaft.
Fold round and glue together the push rod, the collar and the linkages as shown above.
Glue the narrow linkages to the push rod using the grey areas on the push rod to line up the tabs.
Glue the guide into place. Notice that the narrow end is nearest the push rod.
On each of the two box side, fold round and glue the tabs to make a triangular section. Glue the box front to the front of one of the box side with the grey areas showing through as shown above.
Glue the push rod linkages to centre grey areas as shown.
Glue the cam follower ends into place as shown.
Glue the cam followers to the inside of the box front as shown.
Glue together the collar.
Slide the collar onto the push rod.
Glue the linkages bet wee en the cam followers and the collar. Make sure that the collar is free to move up and down.
Glue the second box side into place.
Roll the box round with the cam shaft in place. The handle end of the cam shaft is the end hidden from view in the picture above.
Glue the box closed. Fold round the vertical flaps on the box and glue them down to make triangular sections.
Fold the coin holder round two 20mm coins.
Glue them to the collar.
Make the handle in three steps.
Fold up an glue the two square sections.
Fold the handle in half to make an L shape.
Roll round the long tab and glue it down
Let the glue dry completely before using the mechanism.
Turn the handle and the main shaft raises and lowers once per handle turn. Meanwhile the collar, with the coin moves up and down four times quickly over half the turn then remains stationary.
This mechanism is designed as a starting point for a paper automata. Download it, make it and experiment!
I originally designed it to be used as the mechanism for a dodo model, turn the handle and the wings flap quickly while the body moves up and down slowly.
Use it as a starting point for your own designs. Use it for an angel or a flying horse, whatever you like. The only limit is your imagination!
Over too you!
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