Can I lasercut gears? #
Group Assignment #
For this week, we are using parametric design to make an object from lasercut cardboard. For the group assignment, we cut several squares and joint test pieces to characterize the kerf of the cardboard. We found that the kerf was around 0.2 mm and we adjusted our designs accordingly.
Individual Assignment #
The inspiration for this week’s project are the gear toys made for children, which is an easy intro to learning about gear ratios!
I also wanted to explore the gear generator tool in Fusion, which turned out to be very useful and fun!
Tool Generator #
Here I made a 48 tooth gear with 1.5 mm modules, and a total pitch diameter of 72 mm (I later realize that I would misinterpret the term “pitch diameter”)
48 tooth gear #
Challenges #
In Fusion, the gear generator uses splines to create the beautiful modules, ensuring that the gears will rotate smoothly and not have stress or force concentraitons upon contact. Splines however, do not translate well into CorelDraw, the software I use for lasercutting.
To solve this issue, I imported the dxf into SolidWorks WITHOUT splines, instead converting all the splines into polylines. This results in a lower resolution dxf, but Coreldraw was happy with it.
Polyline Gear DXF exported from Solidworks #
I made a CAD for simple chamfered joints for the box I wanted to store the gears in, but also have holes so I could rotate the gears around themselves as a modular assembly.
Here’s the final box! I underestimated the kerf a bit so the fit was looser than I wanted.
I used chopsticks cut into pieces as the “pegs” for the gearbox.
Reflections #
- Cardboard is not the ideal gear material, many of the gaps in the corrugation made it so that the teeth would interlock and not rotate smoothly
- I misinterpreted what “pitch diameter” really meant, it’s the radius of the original circle the gear generator uses to make gears, and I did not account for the extra space from the modules. The gears did fit pretty well into each other diagonally though (a happy coincidence?)
- Check kerf more precisely when switching to a new laser cutter!