Construction
During the winter quarter, the construction on the bridge began and would continue throughout. As for the building, this project has a total of 19 different parts and 2 sub-assembling. With 6 parts are needed for the bridge and 13 parts are needed for the tower that is going to lift the bridge up. After making the parts needed, the construction of the sub-assemblings.
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Bridge
The bridge consists of 6 parts with 5 different trusses and the bridge deck as shown in figure 11. With these being the parts, only two different parts needed to be purchased for this portion of the project. These parts that were purchased consist of 3/8" x 3/8" x 36" balsa wood rods and a 1/4" x 3" x 36" sheet of balsa wood. Construction of these parts mainly consisted of using a band saw and a chop saw for these parts. the chop saw was mainly used for cutting the sheets to the correct length of 450mm and cutting the angles needed for the trusses. While the band saw was used for cutting a straight edge on the trusses and a larger band saw was used to cut the right width of the bridge deck.
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Tower
The tower that is being used as the lifting mechanism, it consists of 13 different parts. With 6 parts being different trusses and 7 parts the tower deck, rods, and lifting mechanisms. majority of the parts that are going to be made are going to have the same process that was used for the bridge as mentioned. Right now the tower is starting to get the parts made as shown in figure 12. While the gear and prawl are going to be 3d printed instead as shown in figure 13. After about an hour of printing, the gear and praw were done and came out in good condition as shown in figure 14. Also for the tower, the drill press was used for the lifting mechanism.
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Manufacturing Issues
As of now, there has been one manufacturing issue. The first issue that happen was encountered with the inner angular trust. when making the inner angular truss, the student accidentally rotated the truss. The defective piece was used to make a horizontal tower truss. However, this was not the case for one angular tower truss. Figure 15, it shows the wood shatter when making angular cuts from the chap saw. This was most likely due to a knot that was not visible.
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Another manufacturing issue that might be faced is with the printing of the gear and prawl. the main issue with this could be with the part was not adhered to the bed correctly or a block in the pip that feeds the plastic.
Figure 11: Parts of the bridge
Figure 12: Parts of the tower
Figure 13: Printing the Gear and Pawl
Figure 14: Gear and Pawl after printing
Figure 15: Angular truss shattering when being made
Methods
This project's design came down to two simple designs last quarter. So a decision matrix was used to help come up with an idea and the draw bridge design was chosen. Getting the material was easy. All that needs to be done was to buy the material that is slightly bigger than the design and bring it down to size. As for building this project, It came down to three different tools to make the part. a decision matrix was also used here and showed that a chap saw was the best option, with a band saw being the second best option.
Construction Videos
Figure 16: making of part for lifting mechanism
When making the horizontal truss with a hole, this was the only piece that used the drill press. As shown in figure 16, the student was drilling the 1/8 hole needed for the lifting mechanism.
Figure 17: making of structure pieces
In figure 17, the student was using a band saw to make a structured piece. this was manly used for the tower.
Drawing Tree
Figure 18: Drawing tree of the project