Our next step in our trebuchet project is to print actual supports for our arm-counterweight assembly. We generated a very simple design to suit our needs.
Up to this point we had only printed parts for testing the throwing arm. Our initial design for these supports include minimization of material usage as well as several mounting holes to allow us to launch the projectile from different angles. These parts (as well as our previous parts) are all printed via FDM with ABS plastic.
For the supports once again we optimized the print parameters for speed. The layer thickness was set to its maximum of 0.3mm and infill density at 30%. This was because once again we expect the part to be much stronger than necessary and aesthetics are not important.
While printing on FDM printers, we have run into the issue of warpage. This is no different for the supports. However we do not expect it to be a large issue for this part since some cosmetic variations are not important the function of the overall part. The warpage also occurred in the z direction, which is not a crucial direction for the function of the part. as long as it does not occur in the y direction it will not be an issue.
This is a very obvious problem with FDM printers and so far it has affected two parts. This will need to be taken into consideration when choosing what type of process we use for our final prints. We will likely not try to eliminate the warpage bur rather orient our parts so that the warpage occurs in a direction that has no functional effect on the part.
We also printed a new arm that we look forward to testing after optimizing for strength and weight.
We reduced the amount of material needed while still maintaining enough strength to support the arm under full load. This arm also only included the necessary pivot hole since our testing determined our optimal ratio.
Video of the printing process: