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This project is a cam powered T.Rex automata. The head and lower jaw are driven by separate cams which can be interchanged to change the way the T.Rex moves and so tell a different mini-story. The file of parts is available here.

The T.Rex is a fascinating project to make with students aged twelve and up. By building this model, students will be improve their skills in accurate cutting and scoring. Students will also learn how cam profiles can be used to create movement and how these movements can be used to act out a story.


Step 1:

The project parts come as a file which can be downloaded here

Print out the parts onto thin card. (230 micron 67lb). Score along the dotted lines and cut out the holes before carefully cutting out the pieces.

Step 2:

Make up the base and the top in the same way as shown in the picture. Make sure that all the edges are at right angles.

Step 3:

Glue together the four parts of the body.

Step 4:

Assemble the lower jaw.

Step 5:

Glue together the head.

Fold round and glue together the triangular head inner.

Glue the head inner into place so that it is lined up with the crease across the top of the head.

Step 6:

Glue the two lower jaw tabs to the top back of the body. Make sure that the lower jaw is free to move up and down.

Step 7:

Glue the head tab into place on top of the lower jaw tabs.

Step 8:

Fold the legs and arms into half and glue them together to make double thickness card. Once the glue is dry carefully cut out the pieces.

Step 9:

Glue the lower legs to the grey areas on the body. Note that the legs bend forwards at the joint, use this to get the right leg on the right side.

Glue the two arms into position as in the picture above.

Step 10:

Thread the jaw push rod up through the body and glue the tab to the grey area on the underside of the jaw.

Step 11:

Thread the head push rod up through the body and glue it to the head support piece as shown.

Step 12:

Glue the feet to the legs then glue the feet to the box top so that they are on either side of the hole with the back of the foot just touching the back of the box top.

Step 13:

Fold up and glue together the two cam followers. Notice that the triangular section at the end of the cam follower use valley folds.

Step 14:

Glue the cam followers to the grey areas on the front of the box top.

Step 15:

Glue the end of the push rods to the backs of the cam followers. Pushing the cam followers should now move the head and the jaw.

Step 16:

Assemble the two parts of the box.

Step 17:

Glue the box body to the base. Make sure that it is straight and square.

Step 18:

Glue the top to the box, again making sure that it is straight and square.

Step 19:

Glue together the drive shaft tube. Glue the washer to the end.

Thread the drive shaft through the holes in the box and fix the second washer into place. the drive shaft must be free to turn.

Step 20:

Assemble the handle in three steps. Fold over the two main parts and glue to make square section tubes.

Fold one section into the other and glue them at right angles.

Roll round the long tab and glue it down.

Step 21:

Glue the handle to the drive shaft. Make sure that it turns freely.

Step 22:

Making the interchangeable cams.

This project features easily interchangeable cams. Make a set for each story you want to tell. There are two cam sets already included in the pack as a well as a blank set of cams for you to design your own.

Fold round and glue together the cam shaft. Line up the stop with the grey line and glue it into place.

Thread the head cam into place on the shaft. If you are experimenting with cam profiles, don't glue them on yet. Thread the lower jaw cam onto the shaft. Make sure that the read line on both are lined up so that the parts are in sync with each other.

Once you are happy with your cam design glue them to the shaft.

Step 23:

Lift the cam followers out of the way and thread the cam shaft into the drive shaft so that the stop butts up with the box.

Step 24:

This cam pack makes the T.Rex eat. Nom nom nom!

Step 25:

Don't forget to complete the model by gluing the eyes into place otherwise it won't be able to track down its prey!
I was inspired by this so I went out o my shed and found a scrap piece of ply-wood. Then, I slapped this together. It only has a single cam. I'm super happy with this a a first effort at anything cam driven like this. Thanks for the inspiration. <br> <br>
Wow! That is fantastic!
Too bad we have to buy the plans. This is just like an ad.
Amazing instructable! But sad that anyone who wants to make it has to pay on your website for the template. But still an amazing instructable! thanx
Amazing papercraft! One of the best I've ever seen on the web! <br>Can I ask you how do you design them? What software do you use?
Hi Bonfi96, I use mainly Adobe Illustrator witha bit of Photoshop thrown in. I talk a lot about the design process on my website at www.robives.com
i think I'll use inkscape and Gimp :) Thanks!
Yep, that should do the trick!
Nice (both wooden and paper models)
Thats cool. Maybe you could 3d print/laser cut the cams so there sturdier, they looked kinda flimsy. Good job
nice! <br>I always wanted to make something like this, but I don't have fancy woodworking skills, now I can with paper ;-) <br>very clear and complete instructable! thumbs up!

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