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Cam Box: Essential Mechanism to Download and Make



Turn the handle in the Cam Box and the push rod protruding from the top of the box moves up and down. Vary the cam profile to vary the movement of the push rod. Use this model to experiment with how cams work or as the starting point for other character based models.

Members can download this model for free at the link.

Print out the parts onto three sheets of thin card. (230gsm / 67lb is ideal) I used coloured card for a colourful model.

Score along the dotted and dashed lines then cut out the holes before carefully cutting out the pieces.

Fold the cam in half and glue it down to make double thickness card. Once the glue is dry cut out the cam.

Roll up the two tubes. Align the edge of the card with the points of the arrows.

Glue the cam to the cam shaft outer using the grey line for alignment.

Fit the cam shaft inner into the outer lining it up with the two grey lines on the inner tube.

Fold up and glue down the cam follower.

Glue the cam follower end into place.

Glue the short tube down and wrap the cam follower end round it gluing the end down o hold the tube ino position.

Wrap a small coin in an off-cut of card. (1p UKP 1c US 1c Euro are all ideal. 20mm diameter, 4g weight) Glue it to the cam follower as shown

Assemble the handle in three steps.

Make up the base and the top of the box. The triangle tubes are all right angle triangles.

Make up the two sides as shown.

Glue the sides to the top with the grey arrows pointing to the top.

Fit the cam into place and glue on the base.

Fold round and complete the box.

Glue the tab on the push rod to the cam follower.

Thread the push rod up through the hole in the box lid.

Glue the cam follower to the centre front of the box. (The front is the side furthest away from the hole in the box lid.)

Complete the model by gluing the handle to the cam shaft.

Turn the handle and watch the push rod jump up and down in lively fashion!

Next I’ll be completing this Dog’s Dinner prototype and showing how you can use the Cam Box to make the dog eat enthusiastically! Nom nom nom!

2 reviews for Cam Box

  • i attached Walter Rufflers

    i attached Walter Rufflers dragon headmodel

    to this mechanism and made a very scary chomping drogon well maybe its not that scary but it does chomp

    video here

    • Hey Cool, we can attach our T

      Hey Cool, we can attach our T Rex head in the same way. I was wondering what to do with this mechanism (besides Rob's new model coming). You got a nice idea.

      • thanks,
        yes this mechanism


        yes this mechanism will work with any model that has a moveable mouth

        you could also use it to make a tapping foot like a modified version of robs surly jack

  • this is such a fun

    this is such a fun mechanism.while rob is finishig off the models hes working on i decided to play with this mechanism more and modified this free woodpecker model

    and attached it to the cam box

    video here



    • Dear Robives,
      My friends

      Dear Robives,


      My friends and I printed the same mechanisim and it had forgotten parts in the mechanisim, 





      Oliver and Yael 

      • Dear Oliver & Yael,

        Dear Oliver & Yael,

        Please can you let me know where the problem is? I just downloaded it and it seems to be fine.

        best wishes


        • Rob, I just downloaded and

          Rob, I just downloaded and constructed the mechanism. Parts seem to all be there (3 pages?). I wonder if they were expecting the mono colored dog and dish as well.  



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