On Monday, we found that the sled was significantly harder to pull on the grass with the heavier members of the group. With the contest in just one week, with no signs of snow, we realized that we had to change our design or have little to no mobility on the day of the competition.
After devising several different ideas, we decided on mounting the axle under the sled with rope and foam wedges. Holes were drilled into the tube being used for the axle, as well as the rear portion of the sled. Then, rope was fed through the tube, and the tube was filled with Great Stuff foam for additional strength. The rope was fed through the holes in the sled and tied. Two pulling points were also created, with the rope running out to the front of the cart and under the cardboard tubing. This will allow the cart to be lifted and pulled, though how it holds up will depend on the glue linking the walls to the base of the cart. |
Some testing revealed issues with the foam wedges. The glue was not very strong and could not hold the back foam wedges in place, where the axle wanted to move towards. They were already beginning to shear off after a couple tests indoors. However, the glue wasn't completely set at the time either. More glue was added and more rope was put through, this time going around the wedges and the axle for extra support. |
Lastly, we painted our entire cart black, in keeping with the color coding for each lab (black for Tuesday, red for Thursday). Using some florescent green spray paint, we gave it a TRON look.