This past week for ENGI 210 I have been working on making a wooden crate with the OEDK’s woodworking tools. This blog post will cover my process, areas for improvement, and cost analysis for my wooden crate.
Figure 1: Finished crate.
My Process
In short, my process can be summarized as 1) cut pieces, 2) sand pieces, 3) create wood rings, 4) sand wood rings, 5) assemble box, 6) sand box, 7) clear coat, 8) sand, 9) clear coat. These steps will now be described in more detail.
My first step in this process was to cut down the wood planks that we were provided into pieces that were closer to what I would be using for my box. I planned to have a flat, 16 x 16 inch flat base for my box, 3 16 x 16 inch rings that form the walls of the box, and 4 inner supports that bring the box’s height to 12 inches. We were provided with the 16 x 16 inch base pieces. The pieces for the wood rings I got by cutting 6 14.5 inch pieces and 6 16.1 inch pieces out of 2 x 4s, and 4 11.5 inch pieces from 2 x 2s using a miter saw. Note that these sizes were bigger than what their final sizes would be – I wanted them to be too long so I had plenty of room to sand.
Figure 2: Some of my cut pieces.
Next, I sanded down the ends of these pieces to make them perfectly flat so that they would lay flush against adjacent pieces of wood once the box was assembled. I primarily used the OEDK’s belt sander to do this. After this, the 16.1 inch pieces were 16 inches, the 14.5 inch pieces 14.4, and the 11.5 inch pieces 11.4 inches. Now that my pieces were prepped for assembly, I began to make my wooden rings.
I created my wooden rings by putting the corners of two pieces that were to be adjoined into a corner clamp, using two regular clamps to fix the pieces to the table, and then drilling two screws in to adjoin them, as can be seen on the corner nearest the viewer in Figure 1. I repeated this process until each four corners were held together by two drills. For all of the drilling in this project, I used screws that had a 1/8 inch diameter (inside the threads), so I used a 1/8 inch drill bit to drill the pilot holes and a 5/16 inch drill bit to drill the counterbore holes so that the heads of the screws could be drilled flush with the planks. After the rings were assembled, I used a rotary sander to make the corners more flush with each other to maximize smoothness and to remove some of the rough exterior of the wood, and I also used the router on the outer edges of the rings to give them a nice, rounded corner that one’s hand could wrap around nicely. One exception is that I did not rout the bottom edge of the bottom ring since this would be flush with the base piece.
Figure 3: My wood “rings.”
Now, I moved onto assembling my box. I fastened the 2×2 pieces to stand vertically on the base piece with one screw drilled through the bottom of the base. Then, ring by ring, I would slide them over these vertical supports and fasten them with one screw per support. I ended up letting the top of the top ring rest slightly (around 1 inch) above the supports so that there was some space between the rings for a person to put their fingers through if they were to carry it. After my box was assembled, I again used the rotary sander to sand down the edges, especially at the bottom, that were uneven.
Figure 4: My assembled crate.
After my box was assembled, I moved onto post-processing and finishing. I had already evened out my corners quite a bit, so all that was left was to smoothen out the wood and to add finishing coats. I had used 80-grit pads on the rotary sander, so I went thoroughly over the parts I had not used the sander on with regular 80-grit sandpaper. Then, I brought the box outside, added 3 layers of gloss, and let it dry overnight. When I came back the next day, I decided the wood was not as smooth as I wanted it to be, so I went over it again but with 320-grit sandpaper. This gave the wood a smoother feel that I was much happier with. After this sanding, I added two more layers of gloss. At this point, my box was complete.
Figure 5: The gloss I used on my crate.
Areas for Improvement
I have worked with wood occasionally in the past, but only in very small-scope scenarios – this is definitely the most involved woodworking project I have done. With this in mind, I am pleased with how my crate turned out. There are definitely some parts that I could have done better, though.
One thing I could have done better was the counterbore holes. Some of these holes turned out very nicely and the screws fit very flush with the wood, but other times, the counterbore drill bit would wreak unexpected havoc on the wood surrounding the pilot hole, ripping out large chunks of wood adjacent to where I was drilling. I am really not sure what caused this – my technique was the same for each hole, some just turned out ugly. If I were to do this project over, I would definitely use a drill bit that was made for counterboring rather than a regular drill bit, or I would do quite a bit of research on proper counterboring technique.
Figure 6: Counterbore hole error.
Another thing that I could have improved about my box is the fit between the vertical supports and the upper rings. I did not anticipate having this problem, but as I was drilling the upper rings into place on the supports, I noticed that some of the supports were not fitting perfectly flush with the rings. Of course, this could be for a variety of different reasons – the supports might not have had perfectly flat edges or sides, the rings could have been slightly different sizes, etc.
Figure 7: Gap between the vertical support and the wood ring.
The third and final thing I could have done differently is to do my drilling from the inside of the crate. To be completely honest, I did do my drilling on the outside on purpose for this crate, figuring that this would minimize the hassle of having to reach inside the box with a drill to put the screws into place, but in hindsight I wish I had put up with the hassle for aesthetic purposes. I was looking around at some of the crates where the students had put their screws in on the inside, and I think that doing this really improved the aesthetics of the crate’s exterior.
Figure 8: Screws can be seen from the outside of the box.
Cost Analysis
For this project, the elements that could have accrued cost are the wood, the screws, the clear coat, the cost of using the woodworking tools, and the opportunity cost of my time.
Wood
For this project, I used roughly 15.5 feet of 2×4, 4 feet of 2×2, and 1.75 square feet of 9/16 inch plywood (provided base piece). Using average prices between various retailers, this totals about $31 worth of wood.
Screws
For this project, I used 40 screws. Roughly 153 of these same screws can be purchased from Lowe’s for $9.48, so I will estimate that I used about $2.50 worth of screws.
Clear Coat
Most retailers seem to sell a can of the clear coat I used for around $5. I did not use anywhere near the entire can, but it is impossible to know how much of the can I used since I cannot visually see how much of the contents are left. Therefore, I will make a generous estimate of $1 for the amount of clear coat that I used.
Cost of Using Woodworking Tools
For this project, I used a miter saw, a belt sander, a router, a cordless drill, and sandpaper. These materials would all be present in a standard woodshop, but it is difficult to find a standard price online for an hour in a woodshop. For this reason, I’ll estimate a cost of $10/hour to work in a woodshop. I was working with these tools for about 7 hours, so this would accrue a cost of $70 for the project as a whole.
Opportunity Cost of Time
I spent about 8 hours of my own time working on this project, and my time as a Tech TA is valued at $12/hr. Therefore, the opportunity cost of the entire project is $12 x 8 = $96.
All together, the total cost of this project is $31 + $2.50 + $1 + $70 + $96 = $200.50. As usual, a large portion of the cost of this project is associated with the time it spent to create it. While I’m sure I could have reduced this cost somewhat now that I am more familiar with the tools and process, I still think it would take me at least 6-7 hours to create a product of this quality again, so the price would not be reduced too dramatically.
