Lasercutting
Files for LibreCad
What todo
This week, we were given an introduction into laser cutting technology and the laser cutting machine. For the assignment we had to create a 2D design for the laser cutter. As additional conditions the design should contain an engravment and should use joints (not the smokey one) at some point.
Getting some inspiration
At the begining I had to think about what I want to build. Many different ideas shot through my mind but I decided quickly to built a trebuchet. So I drew a sketch with LibreCad. I basicly used the the simple line tool to create all the parts I need. To check the size LibreCad comes with a very usefull measurement tool and a very similar tool measure angles.
Doing the laser stuff
Now it was time for the first cut. Euphoric I cuted the hole sketch in one, thinking my calcultions would fit. I was wrong. But the cut itself was a success. As cutting setting I used
- power 90%
- speed 35
- focus 0.0
- frequency 50
So unknowing of my mistake I tried to assemble my siege equipment and realized that the significant parts, the triangles to stabilize everything, doesn't fit. And the box for the counter weight didn't either. At the box was a forgotten offset the reason.
That Friday I thought about how I could fix the triangle parts and even argument and calculated with fellow students how to do it properly. We decided to go for the new design you see in the picture. That day I also recalculated my counter weight box.
Notes after the second day cutting. My box fits perfectly.
1) The joints work great and I dont even need glue. But the bottom of the box is now to big.
2) The new triangle needed a few tries however fits in the end. BUT. While assembling the last time and one part of the central mast broke down. So I made a new one with from the same sketch. For unknown reason they were to small.
So I assemble everything I could at this point.
The following Monday I measured the real parts and compared the size to the digital sketch. And for what ever reason the one I catted while the first session was 0.5cm bigger than the sketch. Funnily, it fit but so. Hence I redid the sketch with the new size and eh voilà it fits great.
What I learned at this point. It is useful to do a full sketch at first. So you see all the parts you will need. But to recalculate and cutting the different parts I would recommended to break it into many small files.
Assembling
Now that I have all parts I will explain how I assembled it. First of all I glued the two central masts which consist of three pieces together. Followed by the basement of the trebuchet. Protipp: always fix well! After the front cross strive was ready. I embattled one of the central masts with hes triangular support. It wasnt easy to fit it in, but after some work with the rubber hammer it hold without glue. Following glued the rear cross strive.
At this point I created the launch device. I drilled two holes into the assemble counter weight box and put a wire through. I attached this with a knot. Then I stuck two small metal plate on the lumber. one at each end. for the counter weight and the loading bag. In the end I measured the height of the moving beam to shoot. And then stuck it on. I Assemble all parts together. Also the second central mast. It was fumbling until it worked, but it was worth it. I hope this will help you