by Yun-Han Lin
In early March, I made the biggest project that our studio has tried so far. Here’s a peek into the process!
The structure and design were no problem, but its huge size and the trapezoidal structure were the real challenges.
Source of idea
I did a lot of research on similar projects, and most projects I found are small carts for scrap wood. Few people in Taiwan make bigger ones, especially when plywood is more easily obtained in western countries. The following are a few cool works that I have found. In comparison, my own cart was not built for any specific purpose, but simply a combination of several basic designs.
Scrap wood storage cart:https://www.youtube.com/watch?v=jzdZte3UZuo
Basic plywood storage:https://www.youtube.com/watch?v=T16skEZ6JYg
Panel-cutting plywood cart:https://www.youtube.com/watch?v=eHpFGtBsl9k
Lumber storage cart:https://www.youtube.com/watch?v=vG0Sn0grNYc
Using hand circular saw
The plates we worked on came in large size given their length and width, so we might as well use the hand circular saw we had just bought. I used the saw by WORX, coupled with Kreg rip cut, an accessory for the circular saw. The hand circular saw is safer and easier than I expected, and it is, in fact, not that dangerous as long as users pay more attention. The challenging one was fixing and calculation of the back board. Many of the cuttings were done along the long side, which was 2440 mm. Repeated measuring and clamping of the board took longer than expected. The maximum width of Kreg rip cut is only 70 cm, which is often not enough, so I hope that it will come in handy in the future for smaller projects.
Pros & cons using pocket hole jig
When designing, I thought a pocket hole jig would be enough to handle the entire project, but it ended as mentioned in the footage where there was not enough space to reach the screws on the middle level of the trapezoidal structure, because the square screwdrivers by Kreg were too long. Some parts could be reached using shorter screwdrivers or electric screwdrivers with L-shaped extensions, which reminded me that space must be taken into account when it comes to fixing the parts. Working on such a large project, I realize that the pocket hole does not sell because of its better performance, but because it saves time for measuring, leading holes, and turning over sides upon assembly.
To screw the screws in a vertical position on a trapezoidal structure, I 3D-printed a set of jigs. Although the jigs did not turn out work very well, 3D-printing parts can still be useful when it comes to long-term usage during production.
0.5 degrees made a huge difference
Upon assembly of boards into a trapezoidal structure, although 3D-printed parts made fixing easier, the last 5 trapezoidal structure still tilted a bit. I knew that there would be a bit difference, if I used jigs for aligning positions without fixture. What surprised me was that a difference of merely 0.5 degrees could lead to an offset as huge as 10 mm on a side with length of 1300 cm. To align the 5 trapezoidal structures, a very stable fixture is required, or the first trapezoid structure should be fixed as a template for the rest for fixture.
I used 4-inch caster wheels for this project, based on the size of the entire project. Later, I found that a single 4-inch wheel can support 100 kg, so 6 wheels should be enough for my cart.
Notes for cutting upward bevels using a circular saw
To put together a trapezoidal structure, there need to be a few 6-degree bevels. It is crucial to check after cutting, so as to see if the boards on both sides form a parallelogram or a trapezoid. Then, there is the table saw fence. For cuttings done on the side of the table saw fence to have a trapezoid at one cut, instead of assuming the length of one side, the length should be measured from the long side of the board to the short side that the saw blade cuts.
Handles: A handle added can make it easier to pull the cart, so it moves in certain directions easily
Larger wheels: The 4-inch caster wheels could support weight when a cart is loaded, but larger wheels make it even easier for pulling.
More carts to share the loading: After using the cart for a few days, I found that instead of putting everything on one carrier, it is better to build 2 or 3 more carts to share the loading, so that the loading on one is less and they, therefore, can move around more easily.