I just finished testing a boomilever I built. I expected it to hold full weight (following the calculations that Balsa Man (rest in peace) uploaded), but we were only going to test it to 10 kg. However, the boomilever only held around 3 kg. I suspect this is a construction error, as one of the compression members was starting to turn inwards. It seemed that I was not able to align the compression members with the tension members/base properly, which made it hard to set the boomilever up on my testing wall perfectly symmetrical. This led to the rotation of the compression member.
Here is a picture of the remains of the boomilever. As you can see, the compression members and the tension members did not flex at all, but the X bracings were broken because of the turning of the compression member:
When I built it, I first cut my compression members, put them next to each other, and attached the X bracings. I put some thick sticks of wood to make sure the compression members were roughly 5 cm apart to hold the loading block. (However, this time, I'm using clamps so the compression members don't move out of place.)
Then, I built the base and glued my tension members (with gorilla glue) to the base and clamped for 24 hours. However, I noticed that the tension members were not in the exact same plane-one was at a different angle from the base than the other. You may be able to see this in the picture. When gluing, I put the base in between the tension members, attached pieces to it, then added gorilla glue, and then clamped. I think the clamping may have shifted the tension members slightly out of place for some reason (which I noticed when I was building, but it was too late to change anything.
Then, I put the compression members on a flat surface, though the compression members were a little wobbly. The orientation of the compression members was like this:
I put the base/tension members above the compression members at around 13.5 cm(our height). Then, I connected the first tension member to the compression member and glued with CA glue. Then, I flipped over the boomilever onto its other side, connected the second tension member to the compression member, and glued with CA glue. Then, I added reinforcements to both joints and clamped.
Do you know any construction tips that can help with alignment? It seemed like because the tension members (which were the same length) were connected to the base at different angles, it pulled the compression members into an asymmetrical shape, which helped its premature failure. My base was also misaligned, probably because I tried to fix the alignment problem by gluing the tension members on slightly different spots on the compression members. This all also made it difficult to set up on the testing wall. If you have any tips, I'd really appreciate it!
