A STEM Project: A Geneva Drive Mechanism

Geneva Drive Mechanism 

A drive wheel is on the left spindle and a Maltese Cross on the right spindle.

Video of the Geneva Drive Mechanism in action

The Geneva drive mechanism is also know as a Maltese Cross.  It is a gear mechanism that translates a continuous rotation movement into an intermittent rotary motion. In this model, a drive wheel with an elevated circular disc rotates with an attached pin. The elevated circular disc locks the drive wheel in place. When the pin reaches a slot located in the Maltese Cross, the Maltese Cross is rotated by one step.  It takes four steps for the Maltese Cross to make one complete revolution because there are four slots in my Maltese Cross.

Geneva drives have been used in watches to convert the tension of the spring into the ticking of a toothed gear for the second hand movement. When looking at an old watch, the second hand appears to stop and then move forward.  This action is created by this mechanism.

This mechanism has also been used in the film industry to stop a frame of a continuously moving film so that the film will be exposed in front of a picture aperture where it can be projected onto a screen.

Here is the PDF.  I used 65 lb. cardstock. 

https://drive.google.com/file/d/1Ly-NSiCrQ7OCuvMZkdYbw1zJYvXZqJeJ/view?usp=sharing 

Here is the .Studio file.

https://drive.google.com/file/d/1owyyvhtBmgkZYmq290Jo7loEzIwJZcV2/view?usp=sharing

Here is the SVG. The SVG file goes beyond the viewable area.  To see the entire file, zoom out.

https://drive.google.com/file/d/1n2GF89mHjGQKjDv3oOCSG9P_O4OkSlVc/view?usp=sharing

Cut out the above pieces so that the similar pieces may be glued together to make them sturdy.

Three pieces of each component have been glued together. The pin and spindles are shown above.

Apply glue to the tab and fold the pin in half to adhere the glue. Once the glue adheres, make the pin into a tube. Repeat this operation for the two spindles

Thread the pin though the drive wheel.

Glue and adhere the pin to the back of the drive wheel.

Thread the spindle through the washer.  Glue and adhere the tabs of the spindle.  The tabs will make a star shape. Repeat for the other spindle,

Glue the driver to the drive wheel with the circular cutout facing the pin as shown above.

Glue the spacer by aligning the holes to the right side of the base.

Place the drive wheel assembly on the left side of the base and align the holes.

Thread the spindle through the hole in the base and the drive wheel assembly.

Thread the spindle through the hole in the base and the Maltese Cross. Thread the acetate sheet through the two spindles so that the spindles will remain at right angles to one another. Make sure that the pin can rotate successfully.

Thread the knob on the spindle and glue the tabs of the spindle onto the knob.

Apply a drop of glue around the base of the Maltese Cross as shown.  This will adhere the cross to the spindle to complete the Geneva drive mechanism.