Become a Member for free
access to this and other members only projects on the site.See the Membership page for more details.
Already a Member? Log in Here
First Flip Face prototype for members to download and try.
I'm trying out a few different mechanisms so see which works best and thought you might like to play along at home so if you are a member you can download the parts at the link and make your own.
This is a successful mechanism. Turn the handle on the back of the box a full turn and the face turns 180°. The mechanism keeps the face in position when it is supposed to be stationary. The only downside I see is that turning the handle a full turn then stopping isn't the obvious thing to do. Ah well, you try it and see what you think.
Print out the parts onto three sheets of thin card (230 microns / 230 gsm) Score all the dotted lines, cut out the holes the carefully cut out the pieces. Dotted lines are valley folds, dashed lines are hill folds, solid lines show where to cut. Fold up and glue together the side pieces making right angled triangle sections top and bottom.
Glue together the drive stiffeners.
Glue the drive stiffeners to the drive wheel on the grey area.
Fold up and glue together the two axles.
Tightly roll up the two drive pins and glue them shut.
Thread the drive wheel sides onto the drive wheel axle lining them up with the two grey lines
Glue the sides of the drive wheel into place so that they are curved.
Expand the cross holes at the ends of the drive wheel with a cocktail stick then thread the drive pins into place.
Fold over and glue together the geneva wheel so that it is double thickness. When the glue is dry, cut out the piece then fit it to the second axle lining it up with the grey line.
Assemble the handle as shown above.
Glue the two halves of the box together at one end only. Thread the geneva wheel and drive wheel into the correct hole using the picture above as guidance. Glue the washer into place.
Glue the box closed then glue the washers into place on the back. Glue the handle to the axle then glue the face to the tabs on the drive wheel.
Done! Turn the handle a full turn and the geneva drive advances two quarter turns flipping the face over. Rack and pinion next.
Keep up to date: Receive the latest blog post by email
Rate this post:
Back to the pyramid model. I'm making a few more changes to the design. Initially I had the centre section lifting and dropping under the power of a Geneva drive. I wanted to add a little more to the mechanism so I'm now working on a design where the centre section lifts, turns a quarter turn then lowers back into place. I think I have most of this worked out. It is going to feature the tour toothed ratchet gear shown above left in a mechanism sometimes features in retractable ball point pens.
Keep up to date: Receive the latest blog post by email
Rate this post:
I've made a few small changes to the parts so that everything fits together better. Once done I printed out the bits, and put them together whilst watching Dr Who with #1 Daughter.
The paper model is made from two separate modules. The Geneva Drive in one box and the Watt linkage in another. They are connected together with a drive pin. I've glued the two parts together then added a couple of elastic bands while the glue dries. The egg sits on the top.
The egg is a little small for the box so I'm going to remake it 20% larger. After which I'll be fitting a dinosaur into place.
This side view shows the Geneva Drive. The output from the lower drive shaft is connected to the Watt Linkage in the next box.
Keep up to date: Receive the latest blog post by email
Rate this post:
"The egg model would make a nice dinosaur egg" I thought to myself, especially of a dinosaur hatchling could cautiously peep out of the cracked top of the egg. With the egg project as a starting point I had a look round the site for suitable mechanisms. The Watt Linkage is a simple but interesting way for creating straight line motion and the Geneva Drive would work as a nicely hesitant drive. Up a bit - stop, up a bit- stop, then down back into the shell. I kept the mechanisms basically the same as they were in the original download projects but changed the box sizes so that they matched up with each other.
That done it was just a case of joining them back to back.
Inside, I've added an arm to the Geneva Drive output wheel and a drive pin that locates in a slot on the watt linkage.
Next, I'll take the egg project...
...and fit it to the top of the two boxes.
The first draft seems to work well. Next, I'll be making a few tweaks to the base then adding an egg .
Check back for a progress report soon.
Keep up to date: Receive the latest blog post by email
Rate this post:
Become a Member for free
access to this and other members only projects on the site.See the Membership page for more details.
Already a Member? Log in Here
Two corrections and a modification for you to try:
Firstly, I always thought that the Geneva mechanism was named for the Geneva cross, so when I was looking up images to use in the blog and found that the Geneva cross is the same shape as the cross of the Red Cross I was a little taken aback. The cross I was thinking of was the Maltese cross. It turns out that the Geneva part of the mechanism is named for the city of its invention. I've now corrected that on the mechanism post here.
Second correction. The drive mechansim that I have been experimenting with is not a Geneva Stop, its a Geneva Drive. Makes sense. The Geneva Stop is the mechanism originally invented in Geneva. It is used in clocks and watches to stop the main spring from being over-wound. Again, the mechanism post has been updated here.
And for you to try? I have put together a file for members to download with a couple of alternative stop pieces. These parts interchange with the slotted wheel in the Geneva Six project.
The slotted wheels are made in the same way as those in the Geneva Six model. Fold the wheel piece in half and glue it together to make double thickness card then cut out the outline. Glue together the axle. Slide the wheel onto the axle lining it up with the grey line in the centre of the axle.
The new Stop Wheels fit into the project in place of the slotted wheel. This wheel lets the handle turn five full turns in each direction before the drive wheel stops as it touches the outside of the stop wheel.
In this alternative layout, the pin collides with the missing slot stopping the drive wheel turning any further. The handle in this model can turn five and a half turns each way, a half turn extra which may or may not be useful in your project.
So just to be clear, the model shown here is a Geneva Stop or Geneva Stop Works. The model with the fully slotted wheel is a Geneva drive. Sorted.
Keep up to date: Receive the latest blog post by email
Rate this post:
