Vitaly Cherednichenko, Heeyong Kang, Michael Li
03/21/2008
Design Concept
Model kits that allow the user to construct airplane, car, and various other models using balsa wood can be found at hobby shops. Building models with these kits, however, could be time consuming and dangerous for kids since they require cutting and gluing wood pieces. This toy is designed to help children build simple models without the necessity of cutting and gluing the pieces. The toy contains a set of pre-cut balsa wood pieces with slots and holes, and various models could be built by attaching different pieces through these openings. The simplicity of this design may allow the children to have a safer and more enjoyable model building experience.
Design Process
The wood pieces were designed so that they could be assembled to model a car and be modified into an airplane or a space shuttle. These parts were sketched on Adobe Illustrator, but re-sketched on AutoCAD 2004 because it was easier to sketch two-dimensional objects on AutoCAD.
The boundary layers on AutoCAD were set first before sketching. After typing the word 'limits' (without the appostrophe) and pressing enter, the (x,y) coordinate on the lower left corner was specified to (0,0), and the upper right corner was specified to (12,6) (in inches). To draw a line, the letter 'l' was typed and entered. The cursor was clicked at one point, dragged to a different point, and clicked again to complete the line. To draw a circle, the letter 'c' was typed instead of 'l'. The dimension of the shapes were adjusted by clicking on the line/circle and dragging the blue rectangle blocks that appeared on the line/circle. Using these tools, all wood pieces for manufacture were sketched on four separate drawings.
Figure 1. Main Frame.
Figure 2. Rectangle Pieces for Connecting Main Frame.
Figure 3. Wings and Wheels.
Figure 4. Additional Set of Wing..
The laser cutter in the chemical engineering machine shop was used to manufacture the parts above. The laser cutter reads black lines on the sketch for scorching and red lines for cutting. To modify the line color to red, the entire sketch was highlighted by dragging a box around the sketch using the cursor, and the command 'layer' was typed and entered. A window appeared, and by clicking on the color box, the color of all alines were adjusted to pure red (R:255, G:0, B:0). On the same window, the line thickness was adjusted to 0.00001" to match the laser diamter.
Once all sketches were completed, a 36" by 6" balsa wood with 1/8" thickness was prepared and divided into three equal pieces. A 12" by 12" plexiglass was prepared to be used for the wing (Figure 4). After opening the printing software, we placed a slice of balsa wood (12" by 6"), opened a sketch and clicked print. After the preview of the sketch was shown, we clicked "print" again. A new window appeared asking for the type of laser to be used, which was chosen as "balsa wood." The laser cutter automatically cut the pieces after pressing OK, and this step was repeated for Figure 1-3. For Figure 4, we used the plexiglass instead of balsa wood, and the laser type was changed to 'plexiglass.'
Design Issues and Improvements
The overall manufacturing process went smoothly, but there were few limitations in the manufacturing. The main concern was that the laser cutter did not cut the wood pieces as accurately as intended in the design. For instance, the width of the slots on the main frame (Figure 1) was set to 2", and the width of the rectangle pieces (Figure 2) were set to 1.995". This was done to increase the stability of the model by allowing the rectangle pieces to fit tightly onto the main frame. After fitting the rectangle pieces to the slot, however, the gap between the slot and the rectangle piece was about 0.063", which was greater than 0.005" as designed. As a result, the rectangle pieces did not fit as tightly as we expected to the main frame. It is possible that the laser cutter not only cut the lines but its surroundings as well, which would have reduced the length of the pieces.