When designing this bridge, I knew I wanted to have the truss structure on top, as opposed to underneath the bridge. I also knew that I wanted it to be somewhat of an arc shape. Through research, I found that this was most effective and could hold the most weight.
| Bill of Materials - Knex Pieces | ||||
| Part Number | Description | Unit Cost ($) | Nr. of Parts | Cost ($) |
| 1 | 1.25" long chord | $500 | 52 | $26,000 |
| 2 | 1.125" long chord | $1,000 | 52 | $52,000 |
| 3 | 3.375" long chord | $1,500 | 32 | $48,000 |
| 4 | 5" long chord | $2,000 | 0 | $0 |
| 5 | 7.5" long chord | $3,000 | 0 | $0 |
| 6 | chord splice | $1,000 | 0 | $0 |
| 7 | 45 degree gusset plate | $1,000 | 0 | $0 |
| 8 | 90 degree gusset plate | $1,000 | 0 | $0 |
| 9 | 135 degree gusset plate | $1,000 | 12 | $12,000 |
| 10 | 180 degree gusset plate | $1,000 | 28 | $28,000 |
| 11 | 180 degree grooved gusset plate | $2,000 | 0 | $0 |
| 12 | 360 degree gusset plate | $1,000 | 18 | $18,000 |
| 13 | 360 degree grooved gusset plate | $2,000 | 0 | $0 |
| Total Cost | $184,000 | |||
Upon creating this bridge on a scrap piece of paper, I changed a few things about it. At first, I was going to make the arc come to a taller position, but to cut down on cost I didn’t want to have to use any long K’nex chords. I also knew that it had to be at least eight inches flat on top and this was interfering with my design a little bit. However, I opted to have a ‘flat’ arc instead of one that came up to two points at the top like my original plan. Otherwise, my design was pretty much how I envisioned it.
This bridge gave me an idea of what it is going to be like working with K’nex kits. I had grown used to using West Point Bridge Design and it’s just not the same when you have to translate it to real pieces. When using K’nex I had to think about what types of gusset plates were going to work best and the angles I was able to use. I also had to think about the length of each chord piece and if I wanted long ones or many short ones. I hope that when we get to start building our bridges in class my design works well and everything fits together. It is quite hard to imagine a bridge that will work when you can’t play around with the pieces since they are not in front of you.
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