SPIROGRAPH

Source:wikipedia.org

Introduction:

Spirograph is a geometric drawing toy that produces mathematical roulette curves when a point at an external spur gear is traced while it rolls inside an outer ring with internal gear teeth.

https://en.wikipedia.org/wiki/spirograph

In this exercise we are going to learn to build a Spirograph.

Operation:

Spirographs can be manually drawn using two different sized gears (mobile and static), and a pen. Gears provide the mechanisms for guiding the pen, which is controlled by a mobile gear, rotating within a static gear (internal gear). The mobile gear has several holes on its surface to put a pen in it, each of them creating beautiful works of art with the Spirograph. One may also rotate the mobile gear outside of the static gear circumferences to draw different kinds of Spirographs. Spirographs have a unique visual signature, which attracts attention. This is probably because people have memories playing and interacting with Spirograph in their childhood.

Spirographs can be used as a very creative children’s toy by which they can generate beautiful and attractive spiral curves which trigger curiosity and are associated to memories

Material Requirement:

Item Number      Item          Specification         Quantity

1            Hylam Sheet          3 mm           Sq. Feet

2                Bolt                 M3 x 12mm          2

3                 Nut                 M3 x 12mm           2

The Spirograph kit which includes,

• Spirograph static gear (1 no.) with base plate which support drawing paper. ( Module: 3, NumTeeth: inner teeth-33 and outer teeth-46, Pressure angle: 20°)
• Spirograph mobile gear (3 nos.) with 18 hole for generating 18 different pattern ( Module: 3, NumTeeth: 10, 15 and 20,  Pressure angle: 20°)

Procedure:

1. Using a CNC router cut out the base plate, Spirograph static and mobile gear from Hylam sheet.

• Base plate
• Spirograph static gear
• Spirograph mobile gear
2. Align the base plate and static gear with respect to fastener hole
3. Take a bolt one by one insert it inside the hole provided on the base plate and static gear
4. Now take a nut to fasten the bolt with clearance which you required for inserting drawing paper
5. Insert the drawing paper in-between base plate and static gear
6. Mesh the mobile gear with static gear and put pen or pencil in hole presented in mobile gear
7. Ensure pen or pencil touches drawing paper and rotate along static gear
8. Beautiful Spirograph generated on your own

Try some more of our PROJECTS

Suggested project variants:    You can try the following variants:

1)  Calculate the gear ratio required to achieve the 3 pole and 5 pole output curves given above.

2) Verify theory by fabricating inner gears and plotting the real curve. ( use the same outer gear provided )

3) Write a MATLAB code to plot the output curve of a spirograph : given the gear ratio between static and mobile gear.

Product Variants – Tip & Tricks

1.       To get different patterns one can change the size of the mobile gear or the position of the holes.

2.       The hobbyists can acquire a mini hobby CNC desktop machine to quickly go ahead with several iterations of designing the Spirograph.

3.        An outer gear profile can also be made on the static gear for a new pattern. ( epitrochoids )