No Glue Laser Cut Catapult

This catapult was designed with two primary goals in mind: avoiding the use of glue and only using laser cut parts.

If you are looking to get started right away and not make any changes to the design, the SVG, PDF, and Adobe Illustrator files are provided below to load onto your software of choice. Refer to step 1 for assembly instructions.

If you are looking to learn about the design process and make some edits of your own, skip to step 2 for the details of our workflow. Attached are the Fusion file, STEP file, DXF file, and STL file to load onto your software of choice.

Note: when opening the SVG file, notice that it opens with a stroke of 1 and not 0.001. Make sure to change the stroke to 0.001 before laser cutting.

-3mm (0.1 in) plywood

-Laser cutter (we use the Epilog Laser Fusion M2 with a 75 watt C02 laser)

-Size 64 rubber band (3 1/2 x 1/4 Inch)

-Small object to catapult

Here is a visual guide for assembling the catapult.

The two main components of the catapult are the arms and the legs. Assemble these first, then push in the axels for the rotation of the arm and trigger.

Everything below this step will be diving into the nitty-gritty logistics of Fusion 360 workflow, exporting and importing files, using Adobe Illustrator, and laser cutter settings. If you are excited to nerd out and potentially modify this design, keep reading!

-After developing your sketch in Fusion 360, finish the sketch by pressing the green checkmark in the top right corner.

-Extrude the sketch by pressing the letter E on your keyboard, and entering the material thickness (0.1 in). Hit OK.

-From there, you can project the sketch to get the outline of the extruded shapes. If any of your lines are shared by two bodies, you may need to project a second time to get any of the lines you missed.

At this point, you should have a projected layer with the outlines of all of your pieces.

Right click your final projected sketch layer and select Save As DFX. Name your file and select the desired location.

Open your new file in Adobe Illustrator.

Within the properties tab, under appearance, Set the stroke width to 0.001 in, and the stroke color to RGB red (255, 0, 0). This ensures that the laser cutter knows to treat the lines as vector cut lines and not engrave lines.

Note: when opening the svg file, notice that it opens with a stroke of 1 and not 0.001. Make sure to change the stroke to 0.001 before laser cutting.

Here is a general chart guide of settings for different materials.

The laser cutter's speed and power depend on what material and laser cutter you are using. We use the Epilog Laser Fusion M2 with a 75 watt C02 laser.

For the 3mm (0.1 in) plywood in this project, the settings are:

Speed: 100, Power: 20

Process and Developed Solutions:

-The variety in wood thickness and warping of pieces was one of the major issues we came across --one slot would be too big, while another too small. We were able to troubleshoot this by experimenting with different slot heights and adding a taper to most connections in order to make the assembly easier.

-Another issue we encountered was finding a solution to avoid using dowels for the axel connection in order to use only laser-cut parts. Eventually, we discovered that a rectangle can rotate very well inside a hole with a diameter slightly bigger than the width of the rectangle.

Overall, this was a fun and rewarding project to design and cut.

https://creativecommons.org/licenses/by-sa/4.0/deed.en 

This design is licensed under a cc-by-sa 4.0 creative commons license. Tag Make Studio JUMP as an author if you modify and reshare.

Enjoy, and have fun catapulting!

Jack's Urban Meeting Place

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