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Paper Press Ups - Download and make!
Turn the handle on this crank powered model and the paper robot practices his press ups.
Members can download and make the parts for this model for free, thanks for signing up. Non members can download it for £2.50 at the link.
The parts are on four sheets. In the file there is a color version and a line only version. If you are printing the colour version you will need to print each sheet on both sides. Print out the parts on one side, flip the card over and return it to the printer to print the other side. Use 230gsm/67lb thin card for this model.
To make the push rod ends fold over the card to make double thickness card and glue it down. Once the glue is dry carefully cut out the holes.
Then cut out the parts.
Make up the pins by rolling them round so that they end lines up exactly with the triangle arrows then glue down the ends.
Repeat this process with the three pins and the should tube.
Make up the two crank offsets as shown in the picture.
Glue the shorter pin into the short end of one of the crank offsets.
Thread the two push rod ends onto the pin.
Assemble the push rod.
Glue the push rod ends to the push rod making sure that it is kept square to the pin.
Finish off the crank assembly by gluing on he second crank offset then gluing the two longer pins into place making sure to push them completely home.
Glue up the two box sides making right angled tube sections.
Glue in the two box ends.
Assemble the box top stiffener triangle tube and glue it so that it just touches the hinge crease.
The box, ready for the next step.
Fold up the box with the crank in place as shown.
Glue down all the flaps and tabs to complete the box.
Assemble the handle as shown above.
Glue the handle to the crank shaft.
Assemble the upper and then glue the arm side covers into place, use the single and double dots to help with alignment.
Assemble the forearms. Notice that the long tab is a valley fold.
Glue the upper and lower arms together. Glue the elbow onto the side of the arm without the square hole.
Roll round and assemble each leg. glue them together.
Assemble the feet.
Glue the feet to the leg. Glue round the long tabs into the leg.
Assemble the foot push bar and glue it into the foot.
Glue the body support to the two grey areas on the legs.
Fold the tab in the top of the box downwards into the box. Thread the foot push bar down through the hole in the top of the box and glue it to the box tab.
Glue the push rod to the end of the foot push bar.
Roll the slip ring round the shoulder and glue it round onto itself so that it is a tight fit but is free to rotate.
Assemble the body box.
Fit the shoulder tube into the box and glue it into place ensuring that the slip ring can still rotate.
Assemble the neck tube then glue it to the slip ring.
Fit the body to the legs.
Assemble the square shoulder pin
Fit the hands into the arms. The thumb should be on the same side as the square hole.
Thread the square pin through the shoulder tube, glue the two arms to the pin.
Glue the palms to the top of the box. Complete the model by assembling the head and gluing it to the neck then gluing on the eyes.
Turn the handle to exercise your robot!
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Exercise is good, so I'm told. But if you don't have time for it you can always create a paper avatar to do it for you. Hence the push-ups model I'm working on now. Soon I'll have the vicarious physique of a seven stone weakling.
So on to the mechanics! Sometimes with mechanisms the best way to create a movement is not to mirror reality. When I'm doing pushups (ha.) The muscles in my arms, chest and shoulders contract to lift my body from the ground. In this project I'm actually lifting the body via the feet.
I see two main competing ways to achieve this, via a cam or using a crank. Cam first. I fitted a cam to a drive shaft and threaded it into the box. The cam rests against a cam follower linked directly to the feet. Turn the handle and the body lifts up and down.
It works reasonably well, the plus side of the cam is that you can create any movement profile you want within the limits of the cam follower. In this case I was able to add a little dwell at the top and bottom of the travel, a slight pause at each extreme of movement. The downside - there is always a downside - is that the movement is only driven up and relies on gravity for the return. Not a huge problem but it does give a slightly floaty feel to the movement.
The red writing on the side is where I measured up for fitting a crank.
Onto the crank. I used the crank template I'd created in the recent crank slider project with the throw set to 9mm. Everything fitted together nicely, I simply needed to turn the box top round so that the feet were at the other end away from the drive handle.
Looking good! I must say I was surprised just how much more satisfying the movement is using a crank. Very positive in both direction and the lack of dwell doesn't seem to be a problem. Yep. I'm going with that.
It'll look better with two arms and a head. I'm still not sure about the character though. Robot? Pirate? Gentleman in a top hat and tails? Hopefully inspiration will strike soon.
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The co-axial crank slider mechanism is designed to be a starting point for your own projects. As the handle is turned the outer tube moves up and down 90 ° ahead of the inner tube creating an organic, fluid motion which can be harnessed for your own character designs.
Members can download the parts for free, thanks for signing up! Non-members can download the project for the usual £2.50.
Print out the parts onto thin card (230 micron / 67lb) Score along the dotted and dashed lines and cut out the holes before carefully cutting out the parts.
There are four paper pins that need to be made. Pre-curve the pieces round a pen or pencil then roll them round so that the edge exactly meets the points of the red arrows. Apply glue to the inner surface and glue the pin together.
Make up the two crank centre pieces as shown.
Glue the two crank centre pieces together. Notice that the square holes are facing in opposite directions.
I'm pleased with the new design for the crank sides. They are each made from a single piece of paper and their size and therefore their throw, can be changed very easily. Make up the two crank sides as shown.
I'm planning to create a single crank slider project using this design shortly.
Fold over the push rod ends and glue them down to make double thickness card. Once the glue is dry, cut out the centre holes then carefully cut out the pieces. there are four push rod ends.
Make up the short push rod as shown. Notice the triangular section tube. This give rigidity to the piece.
Glue two of the push rod ends into place using the grey areas for alignment. Push one of the pins through the holes in the push rod ends and make sure that the pin is at 90° to the shaft before the glue dries.
Fit the other push rod ends to the other push rod in the same way.
Glue the ends of the pins into the crank middle as shown. Make sure none of the glue gets onto the push rod ends.
Glue the crank sides and remaining pins to complete the crank shaft.
Assemble the slider tube and glue the slider tube end into place as shown.
Thread the slider tube over the long push rod then glue the tab on the long end of the short push rod between the two tabs on the end of the slider tube.
Fold up and glue down the tabs on the bottom edge of the two box sides to make right angled triangle tubes.
Glue the two box pieces together along one edge. Fold up the box and fit the crank assembly into place.
Fold the box round and glue it closed. Glue down the two flaps on the box base stand the box on a flat surface as the glue dries to make sure that everything is square and flat. Fold the long tabs into the box and glue them down on the inside walls of the box.
Assemble the outer slider tube and glue it to the hinge on the box top.
Assemble the handle in three steps. Glue up the two square tube.
Fold up and glue one tube into the other.
Roll round and glue down the long tab.
Glue the handle to the pin.
Complete the model by threading the lid down over the push rod and gluing it to the box.
This is just the starting point. Use this mechanism to bring your own characters to life!
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Keep your Crank Zine pristine with this Crank Zine Sleeve, a free download for all paid members. Download, and follow the instructions on the sheet to make your own.
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Check the end of the post to find out how you can own a limited edition signed & numbered Crank Zine. All gone! Thank you to everyone who bought one.
Latest in the Pocket Paper Engineer series of zines, download the crank zine and find out how you can use cranks in your paper projects.
If you are a members you can download the file for free from the link above. Non members can download this and all the other zines for £2.50 for the full set.
Download the file and print it onto standard printer paper. Make sure you set the printer to 'Scale to Fit' so that the whole of the art work is printed out. With a sharp knife or scissors cut accurately round the outer black line.
Fold the sheet in half with the crease running across the shortest half. Run your finger along the crease to make sure that it is nice and crisp.
Open the sheet out then fold the sides into the middle so that the edges touch the centre crease.
Unfold the sheet then fold the paper in half length-wise.
Open the paper. Use your sharp knife and ruler to cut along the central black line. Do not cut beyond the black line.
Fold the paper up into a cross.
Carefully fold the booklet flat to complete your zine.
The layout above shows where the fold and cut lines are on the finished zine. Dashed lines are hill folds, dotted lines are valley folds. Solid lines show where to cut.
Limited Edition.
I have printed out and made ten these crank zines. Each one is then signed and numbered. I will be happy to send out a zine to the first ten people who send in a donation of at least £3ukp / $5usd.
All gone!
Enjoy!
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The locus is the technical name given to the line that a point traces out as it moves. In mechanisms the locus is often not the shape that you would predict. Changes in variables, such as the lengths of the pieces or the position of hinges can make a big difference to the locus. As part of the forthcoming Cranks Zine I wanted to show the way that the geometry of a box can change the shape of the locus of a push rod. I put together this crank/slider mechanism using split pins as axles. The baseboard has three alternate axle holes 5cm apart. There are a matching set of 5cm spaced holes on the long push rod. Using a pencil or pen I could then trace out the locus.
By pinning the rotating disk to each hole in turn I traced out three three different locii. Orange with the disk at the orange arrow, black at the black arrow and the widest red shape was with the disk fixed at the red arrow. I have then traced these shape into the computer and copied then acoss to the Crank Zine.
These three shapes are created with the disk fixed in the middle hole, the pencil marking out the locus at each of the three holes in the push rod. Interesting stuff!
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Turn the handle and the remorselessly hammers anything in its path. This hammering robot uses a four bar linkage to create an interesting motion driven by a turning crank.
Members can download the parts for free at the link above. Non-members can download the parts file for £2.50.
The file comes with both coloured and uncoloured pages. Print out your choice of pages onto thin card (230 micron/ 67lb) Score along the dotted and dashed line and cut out the holes before carefully cutting out the parts.
Fold up and glue together the three crank parts.
Glue together the two crank joiners.
Fold the push rod ends in half and glue them down to make double thickness card. Once the glue is dry carefully cut out the parts.
Glue together the push rod. Glue the push rod ends to the grey areas.
Glue a crank joiner to the longest crank piece then glue one of the other crank pieces into place. Use the grey lines for alignment.
Thread the push rod end into the longer crank piece. Glue the other crank joiner and crank into place to complete the crank assembly. The push rod ends must be free to turn.
Fold round the tabs on the side of the box parts to make right angled triangle tubes.
Glue the two box halves together making sure that they are aligned accurately.
Assemble the box top stiffener and glue it to the box top so that it just touches the edge of the hole nearest the centre of the box.
Glue one side of the box top into place. Note that the crank holes and the box top hole are both at the same end of the box.
Fit the crank into place so that the longest side of the push rod is closest to the box centre.
Glue the box closed with the push rod emerging from the box. Glue the washers into place.
Assemble the crank handle in three steps: Fold up the two main sections and glue them down. Fold one square section into the other and glue. Roll round the long tab and glue it down.
Fold the two sides of the body front and glue them down to make right angled triangle tubes. Flip the hinge tab out as shown.
Assemble the arm holder and glue it to the hinge tab using the grey area for alignment.
Glue the linkage together and glue one of the end tabs to the centre of the arm holder. Notice that the triangular face of the linkage is pointing to the front of the body.
Fold round and glue down the triangular section on the back of the body back.
Glue the body back to the body.
Glue the hinge into place.
Make up the hammer as shown above.
Glue the tab on the front to the body to the grey area on the top front of the box.
Glue the tab on the end of the linkage to the box top stiffener. Let the glue dry completely.
Glue the push rod to the hinge. While the glue is still wet make sure that the crank can turn a full circle easily. You may need to slide the push rod up or down on the hinge before the glue is completely dry to achieve a smooth motion.
Glue the handle into place.
Glue the neck to the inside back of the body lining it up with the grey area on the neck piece.
Assemble the nose and head.
Glue the head to the heck.
Turn the crank handle so that the body is as far back and down as it goes. Glue an arm to the arm holder so that the fist is directly above the head.
Add the second arm and glue the hammer between the two fists.
Turn the handle and the robot will activate his mighty hammer. Use it for smashing all sorts of thins such as scrunched up tissue paper or perhaps a pile of feather! Might indeed!
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A double crank model to down load and make. If you are a member you can download the parts at the end of this blog post. Non-members can download the parts for a small fee in a couple of days.
Print out the parts onto thin card (230 micron/230 gsm) Score along the dotted lines and cut out the solid black lines. Grey areas show where to glue.
This animation shows the completed model in action. The single crank shaft drives two separate push rods one inside the other. The motion of the outer push rod follows ninety degrees behind the motion of the inner pushrod resulting in this interesting fluid movement. It should be a good starting point for a number of different paper animations!
So, parts and glue (PVA - white school glue) at the ready. Time to start building!
The third and forth pages of the file contain the parts of the inner and outer push rods respectively. I printed them onto different coloured card to make it clear which part did what in the final model. I used orange for outer and pink for inner.
There are four linkage sides to make up. For each one follow these steps.
1) Fold the card in half and glue it down to make it double thickness card.
2) Set it to one side until the glue is completely dry. If you try and cut it while the glue is still wet there is a risk of ripping the card.
3) Once dry, use a sharp knife to cut out the centre hole.
4) Complete the part by cutting round the outside.
Assemble the linkages by gluing on the face parts being careful to line up the end with the small arrow on the side (arrowed above).
Complete the linkage by gluing on the other side and gluing the tab to the end.
Fold round and glue together the outer push rod tube.
Glue the outer push rod side into place carefully lining it up the edges with the top of the tube.
Fold round and glue together the inner push rod.
Fold the inner push rod end in half as shown.
Apply glue to the sides of the push rod end and thread it into the inner push rod so that it is lined up as shown.
Thread the inner push rod into the outer push rod.
Assemble the two halves of the crank as shown above. The diagonal piece in the tube gives the tube rigidity. Each crank half consists of a long piece and a short piece. Glue the two crank parts together using the grey areas for alignment.
Thread the linkages onto longer sections of the crank halves as shown above.
Glue one of the cranks to the central section of crank joiner strip lining the crank up between the small arrows and the dotted line on the strip.
Fit the other crank half to the back of the top half of the crank joiner centre section. Note that the second crank half is rotated ninety degrees.
Fold the remaining flaps on the crank joiner round and glue them to the crank halves making triangular sections.
Glue together the box top and slider tube.
Thread the slider tube into the box and glue down the tabs front and back.
Fold the tabs round on the sides to make triangular sections as shown.
Carefully glue the side to the box top. Notice which way up the box top is on the photograph above.
Thread the push rods up through the slider tube.
With the shorter linkage lined up under the inner push rod, fit the crank end into the hole in the box side.
Glue the two tabs in the ends of the linkages into place on the inner and outer push rods.
Assemble the handle in three stages. Fold the two halves up to make square section tubes.
Fold and glue one half inside the other.
Roll round the long tab and glue it down.
Complete the model by gluing on the second side carefully and accurately then adding the handle.
Once the glue is dry, turn the handle and watch how the intriguing motion works. Use this as a free standing interesting mechanism or as the starting point for your own designs. Let me know how you get on!
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I've completed the double crank mechanism and done the photography ready for the instructions. If you are waiting for the parts to have a try yourself I'm afraid you are going to have to wait another day. Apparently there is some sort of family celebration coming up and I've called upon to assist in the preparations. I know! Don't they realise that there is cardboard engineering to be done?!
Anyway, to keep you going, I've put together this animation so you can see what I've been talking about. I really like the fluidity and organicness (is that a word?) of the movement. Hope you like it too!
Parts tomorrow.
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I have completed a working draft for the double crank mechanism. I've cut out parts ready to photograph so hopefully it'll be on the site for members to experiment with tomorrow.
I extended the inner push-rod linkage by 15mm. This reduces the side to side movement and stops the parts binding. Movement is now smooth and silky. The inner link now goes right inside the outer push rod. It'll all become much clearer when I add an animation and a model for you to try tomorrow.
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