Part of the process of making the revised Big Gear experiment is this long flexible rack. It got me thinking about yet another possible mechanism for the flip face project.
I constructed this box with a curved top and a slot...
...fitted a slightly shorter rack into the slot...
...and added a pinion. (With involute gear teeth of course)
With a second side in place holding the pinion, it is just a case of pulling either hand to rotate the axle.
Next, a redesign of the flip-face artwork. As I may have mentioned, it was beginning to creep me out.
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All the parts done and the layout complete. Just need to add colour!
Dial in the combination...
Slide down the sleeve...
Open the drawer. Ta daa!
One question. At the moment, the side of the box is open, I'm a mechanism geek so I like to see what is going on but it does mean that you can open the lock just by looking. Should it be covered? Should I make covered mechanism an option?
*------------------ edit --------------------*
Details of the drawer showing the flush mounted handle which gives you something to grab whilst at the same time allowing the sleeve to shut over the drawer front.
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Youtube video showing how the paper safe mechanism works.
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Rotary motion is motion in a circle. As a mechanism rotates it turns about a fixed point. The speed of rotation is measured in revolutions per minute or rpm. This the number of complete rotations made in one minute.
Using Flash
It is the starting point for many mechanisms. Measurement: Rotary motion is measured in either angular velocity, the number of degrees turned in a given time, or in revolutions per minute (rpm). The direction of turn, either clockwise or anti-clockwise is also part of the measurement of rotary motion. The strength of rotary motion is known as the torque, the turning force. Torque is measured in Newton Metres defined as the force of one newton acting at a perpendicular distance of one metre from the axis of rotation.
Examples of mechanisms using rotary motion are wheels, helicopter blades, gears, volume knobs, steering wheel, washing machine drum and the London Eye
ConversionsRotary motion to: |
Transformations |
|||
|---|---|---|---|---|
| Linear Motion | Wheels. Rack and pinion. |
Increase / Decrease | Gears. Chain. Worm gear. |
|
| Reciprocating Motion | Piston. Geared mechanism. Cardan gear. |
Reflect | Gears. | |
| Oscillation | Crank. Quick return. |
Rotate | Bevel gear. | |
| Intermittent Motion | Geneva Drive. | |||
| Irregular Motion | Cam. |
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A belt drive with two drive wheels is useful for transmitting rotary motion from one place to another. By changing the size of the wheels it is also possible to change the speed of rotation. I've put together a couple of new pinions for the Belt Drive model, one with four teeth and one with twelve teeth.
I fitted these into a box and joined them with a belt. I've added the drive handle to the twelve tooth wheel. Turn the handle and the small wheel spins round three times as fast (12/4) as the drive wheel.
I could have fitted the handle to the other wheel and had the speed reduced to a third.
I've added these parts to the belt drive download. If you have already downloaded it, re-download now to try this model out. The instructions for construction are basically the same for both projects.
I'm pleased with the way that this mechanism is working, time to start fitting it into a character based automata!
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The rack and pinion is used to convert between rotary and linear motion. The rack is the flat, toothed part, the pinion is the gear. Rack and pinion can convert from rotary to linear of from linear to rotary.
Using Flash
This is the third draft on the rack and pinion animation. It should display in either Flash or HTML5 depending on which browser you are using and should be visible on a wide variety of platforms.
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Belt drives can be used to transmit power from one place to another. The typical belt drive set-up has at least two wheels and a belt connecting them together. In a mechanism using stronger materials such as wood or metal it is possible to stretch an elastic belt between the two wheels and rely on friction to make them turn. In a paper model this is not possible. To link the belt to the wheel in this project the wheels are fitted with paper studs which match up with holes in the belt. As one wheel is turned, the belt is pulled round and this in turn drives the second belt.
Print out the parts onto thin card (230 gsm / 230 micron)
Score the dotted and dashed lines, cut out the holes and carefully cut out the parts.
The completed project in action.
Glue the studs to the wheel using the grey areas for alignment.
Fold round the wheel and assemble first one side with the tabbed end (Arrowed) then the other side to close the wheel.
Fit the axle into the wheel lining up the faces of the wheel with the two grey lines on the axle.
Fold round and glue the flaps on the box top and bottom to make triangular section tube sections. These will add strength to the box.
Join the two ends of the belt pieces together to make a closed loop.
Assemble the handle in three steps. Fold up the two square sections. Fold one section into the other. Roll the long tab round and glue it down.
Wrap the belt round the two wheels.
Fit the wheels into the holes in the side of the box.
Wrap the box round and thread the other end of the axle into place.
Glue the box closed and glue down the four flaps top and bottom.
Glue on the four washers using the grey areas for alignment.
Glue the handle onto the shaft to complete the project.
Now includes to mkII belt drive with different size wheels!
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The piston mechanism is used to convert between rotary motion and reciprocating motion, it works either way. Driving the wheel will move the piston back and forth, in this form the piston can be used to pump liquids for example creating the high pressure need in a good coffee machine.
Alternatively the piston can be driven back and forth commonly by steam (in a steam engine) or flame (in a petrol engine). In this form the piston is used to convert reciprocating motion into more useful and usable rotary motion.
Notice how the speed of the piston changes. The piston starts from one end, and increases its speed. It reaches maximum speed in the middle of its travel then gradually slows down until it reaches the end of its travel.
Using Flash
You can download and make your own working piston mechanism here and find out how it works first hand.
Thanks for your feedback about the previous post. It looks like Adobe Edge isn't ready yet, it's a shame because it is nice to use. I've gone back to creating animations in Flash, converting them using Google Swiffy and adding a snippet of home grown code to display either the Flash version or the HTML 5 version depending on which browser is being used.
Does that work for you?
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The piston mechanism is used to convert between rotary motion and reciprocating motion, it works either way. Driving the wheel will move the piston back and forth, in this form the piston can be used to pump liquids for example creating the high pressure need in a good coffee machine.
Alternatively the piston can be driven back and forth commonly by steam (in a steam engine) or flame (in a petrol engine). In this form the piston is used to convert reciprocating motion into more useful and usable rotary motion.
Notice how the speed of the piston changes. The piston starts from one end, and increases its speed. It reaches maximum speed in the middle of its travel then gradually slows down until it reaches the end of its travel.
You can download and make your own working piston mechanism here and find out how it works first hand.
I created this animation using Adobe Edge. Edge is a new tool for creating HTML 5 animations - much more standards compliant than Flash. It is currently a free download from Adobe Labs
I have put the animation up without a Flash alternative to see how it goes. I'd be grateful to hear feedback about if it works for you. If possible please could you also let me know your operating system and browser.Thanks!
(Just to be clear, there should be an animation showing a piston working just above the picture of the crank mechanism project)Keep up to date: Receive the latest blog post by email
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In the words of '68 The Outsider's song 'Bend me, shape me, anyway you want me" The perfect lyric for the poseable paper character. So it is that I'm experimenting with a joint to join hips and body together. Such a joint needs to be able to bend side to side and back to front and perhaps even allow the body to rotate. That's two, perhaps three axis of rotation.
I constructed this centre block using the same rotary joints as featured in the stick-man model. By adding the joints to two faces I add an extra axis of rotation. Left/right and front/back
...now I just need to add rotation.
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