A free mini-zine for everyone to download and make. This pocket size booklet is a guide to using cams in your paper animation projects.
Skip to the end of this post to find out how you can receive one of the limited edition signed and printed versions!
(Only 20 available ) All gone! Look out for the Lever-zine coming soon!
Download the file and print it out onto ordinary printer paper. Set the print-out to "Scale to fit" so that it prints as large as possible on the page. If you are using an inkjet printer let the ink dry completely.
Carefully cut out the page along the thin black border line.
Fold the page in half along the shorter centre line. Make sure that the crease is accurately lined up with the centre of the page and that it is crisp and sharp.
Open out the page then fold the two edges into the centre crease, again paying attention to accuracy.
Open out the paper again then fold and crease along the long centre line. (Accurately!)
Take a sharp knife and cut along the centre black line starting at the point arrowed above and stopping at the end of the line.
Fold the paper in half along the long centre then scrunch it up to make this cross shape.
Fold the pages round as shown. Place the completed mini-zine on a flat surface and rub over the creases to make them crisp and sharp.
Done!
The result should be like this where black lines are cut lines, dotted lines are valley folds and dashed lines are hill folds.
Learn all about cams by reading the booklet!
I have printed out twenty copies of the Using Cams Zine which I will be signing and numbering. If you would like to receive one of these mini marvels I'm asking for a donation of at least £2ukp / $3usd after which I will be delighted to post one out to you anywhere on earth! Click on the donation button above and fill in your details. All gone!
Let me know what you think of the zine format in the comments below. Thanks!
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The heart of many automata, both traditional and the paper variety, is the cam. The cam is perhaps the most flexible way of driving a mechanism. By changing the shape of the cam profile all sorts of different movements can be described.
But on its own, a cam just goes round and round. To use the movement the mechanism needs a cam follower, the part that runs along the cam's surface. In more traditional automata, made from wood and brass, it is quite possible to run the cam follower so that it is perpendicular to the cam, as in the first picture above. In paper based models this doesn't work so well. By their nature paper models have more flex and tolerance. A perpendicular cam on a paper based model will tend to flex and bend rather than running smoothly up and down, not what you want! Paper is at its strongest when it is under tension (being pulled) To use this strength, cam followers in paper models tend to drag across the cam surface (above right)
Using Flash
The design of the part of the cam follower that touches the cam is important. There needs to be a finger shaped end to closely follow the surface of the cam. More complex curves need a narrower finger but, as is often the case with engineering and design, there needs to be a balance between fineness and strength. The animation above shows how well the narrow cam follower follows the cam compared to a stronger wide one.
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I've been working on the Early Bird model. I've repositioned the bird further along the base and hooked up the worm.
I think I'll have to extend the box a little further so that it fully encloses the worm's hole.
I've made up a snail cam with a 15mm drop. Next step is to fit the cam into the box and add the ratchet. Fingers crossed that there is room!
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Which Came First? Something of an engineer's joke just in time for Easter. Turn the chicken shaped cam and the egg pecks back and forth (!?) Originally published on the Flying Pig website I've made a few minor updates and re-done the photography. Paid members can download this model for free, none members can download it for a modest fee.
Print out the parts pages onto thin card. (230 micron / 230 gsm) Score the dotted lines and cut out the holes before cutting out the parts.
Fold the chicken on half and glue it back to back to make it double thickness. Fold the tabs out so that they don't stick together.
Once the glue is dry, cut out the chicken.
Fold up the cam shaft and glue it together.
Slide the chicken onto the cam shaft using the letters on the tabs for alignment.
Glue together the two parts of the box.
Assemble the cam follower as shown above.
Thread the end of the cam follower with the three tabs up through the hole in the top of the box. Glue the single tab to the front of the box. Glue the three tabs to the box top in the grey areas.
Thread the chicken into the box so that it is facing forward.
Glue the egg inner together and glue it to the back of one of the egg pieces as shown.
Glue the other face of the egg into place.
Assemble the handle by folding the the two square section tubes. Fold it in half and glue it together.
Glue on the two washers. Glue on the handle.
Finish the model by gluing the egg to the top of the cam follower assembly.
Once the glue is dry, turn the handle to see the egg peck!
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This question was posted on the cams page of the mechanism pages. It's interesting so I thought I'd re-post it to the blog where more people would see it.
Hi Rob, found the site this week and really like it, nicely done!
I was trying to envision a cam that could be used to make the cam follower appear to pause at both and upper end and lower end (in your animation it pauses at the lower end).
To do that, would you just draw two circles of different dimensions, connect their outer edges, and spin along the center of the bigger circle? I added to picture to show what I was talking about:http://www.tooz.us/cam.jpg
I realize that the pause and the top and bottom will be of different lengths of time, but that seems necessary to get the cam follower to roll along nicely.
Thanks and keep up the great drawings!
A cam is, at its simplest, a surface describing a movement, all wrapped round in a circle. The highs and lows of the surface create the highs and lows of the cam follower's path.
To create a flat area in a cam, an area where the cam follower doesn't move up or down, you need an area that follows the circumference of the circle centred on the centre of the cam.
In this cam there are two quarter turn flat areas. In a mechanism this would give you a cam follower that stayed high for a quarter turn, drops down, stays still again for another quarter turn then rises again. It should do what you are after.
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Downloadable interchangeable cam model. Build the model and learn first-hand how cams work! If you are a member, first of all, thank you - I couldn't do this without you! Secondly, as a member you can download the parts at the end of this blog post. None members can download the file for a modest fee, for which, thank you as well. Print the parts out onto thin card (230 micron / 230 gsm is perfect)
Score along the dotted lines and cut out the circular holes before cutting out the pieces. (Don't cut out the square hole in the box top. Follow the instructions below to complete the model.
The completed Interchangeable Cam model.
Fold round and glue down the box top as shown above. Make sure that the end touches the crease line at the point arrowed. Set it to one side to let the glue dry completely.
Fold over the cam and glue it together. Make sure you don't get glue on the four tabs.
Cut out the cam.
Make up the cam shaft and glue the cam in place, make sure that the orientation is the same as in the picture.
Fold round and together the two box stiffeners. Glue them to the inside of the box parts so that they are just above the circular hole.
Glue the two box halves together as shown.
Retrieve the box top, carefully cut out the square hole through both layers of card.
Glue the top and bottom of the box to the box, use the grey areas for alignment.
Make up the cam follower and and the push rod.
Thread the drive shaft through the two holes in the box. Note the square grey areas are to the back of the box. Glue on the washers making sure that the drive shaft is free to rotate.
Assemble the handle in three steps. Fold round the handle parts to make a square section. Fold one section into the other and glue down. Roll round the long tab and glue it down.
Glue the handle to the drive shaft.
Glue the cam follower to the box top then glue the push rod to the cam follower.
Complete the model by slipping the cam into the drive shaft.
That's it! Turn the handle, the cam turns and the cam follower moves according to the shape of the cam. Find out more about how cams work in the mechanisms section.
The kit comes with four different cam profiles shown above as well as a sheet of blank cams for you to design your own. Use the model to help you design cams for your own models!
Part of the Paper Mechanisms Multi-Pack - Buy and save!
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All done, I've completed the interchangeable cam model, complete with interchangeable cams!
All I need to do is write the instructions. Tomorrow. I promise.
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Here's the latest cam model in its final form, just the photography to do.
The cam slips out from the handle tube and can be replaced with a cam with a different profile. I'll bundle a few cam designs in the final package as well as a blank cam so you to try your own designs.
Hopefully I'll get it completed tomorrow.
I'm stopping for the evening now, I have a proper case of man-flu and feel lousy. Bleugh.
Night all.
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I've spent most of the day trying to work out whether I should be using Flash or Blender for some new mechanism animations I'm planning. At the moment I'm leaning towards Blender, it seems really powerful but I'm just in the foothills of the learning curve and it looks like a long way up!
I've also made a start on my next project for the mechanisms section. In this model the cam is fitted on a short axle which thread inside the tube with the handle, that way you'll be able to pull out the cam and replace it with a different one. Early stages but I think it'll be a fun model to demonstrate cams in action.
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The Agreeable Sheep has moved from the Flying Pig web site to her new home here at robives.com. As a member you can download the parts file for free at the bottom of this post - I hope you enjoy it.
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.) A pair of tweezers will also be useful.
Print out the parts sheets onto thin card. Note that the parts sheets are marked front and back. Print out the front, flip the card over, pop the card back in the printer and print the back. 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.
Fold the body inner round and glue it together. (1)
Glue the body inner into the body. Use the two very small dots on the outside of the body to line up the diagonal corners of the body inner. (2) You might need to hold the body up to the light to see through it.
Roll the body round and glue it to the other side of the body inner. (3)
Assemble the head. (4)
Glue the neck to the head. (5)
Glue the neck to the body inner. (6)
Fold the two flaps at the bottom of the Box round and glue them into place. (7)
Fold round and glue the Cam Follower. (17)
Glue the Cam Follower into place in the box (18)
Fold round and glue the Push-rod. (19)
Thread the Push-rod up through the hole in the top of the box and glue it first to the inside of the Head (20)...
...then to the Cam Follower. (21)
Finish off the model by gluing the Box Back into place on the back of the model. (30)
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