Project Completion:
What's Next: Refinish Baseboard

Process Journal

CNC Prototyping

Earlier this year, in my class on CNC prototyping we were tasked with designing arts and crafts carts for local teachers. This was an incredible opportunity especially because I have been working part-time at one of the elementary schools in the valley and decided to use this assignment to help the teachers I work with on a regular basis. I first interviewed the teacher I wanted to work with for this project to get a better understanding of what her classroom needed most. Then with her specifications in wind I worked to create a cart specifically to address organization in her classroom and allow her art supplies to have a more specific space. The design was created in Fusion360 for ease of working from my laptop and then converted to a flat pattern in Rhino where I tested the fit of the pieces using a scale factor of .4255 so that the material depth was comparable in my foam core model to the full scale piece out of plywood.
Once I had confirmed that my joints were all functional the next step was to prepare a toolpath in order to cut out my pieces on the Techno Isel CNC router to do this I brought my full scale flat pattern into the sign making software Vectric Aspire as a .dxf and used the tools provided within that software to program a toolpath that the CNC router is able to read. While programming my toolpaths I realized I was over the allotted 1 sheet of plywood for this project and was advised by my instructor to continue with this current design. I then started the process of cutting out my pieces and my first file turned out exactly how I had expected; however, when I went to load my second file I realized that it was not being read correctly and was putting the origin in the wrong place in relation to the pieces. Because of this I went back in into Vectric Aspire to make a new file. Once I had made this new file and was once again ready

to cut out my remaining pieces I was informed we had been having some accuracy issues because of drill bit sizing for the Techno Isel CNC so rather than try cutting out my pieces and risk wasting material I set out to try and resolve these inaccuracies.
To do this I made another Vectric Aspire file with testing slots so I could go in and change the size of bit we were telling the machine it was using to see if we could try to manually reverse the inconsistencies in the width of slot cuts, after finishing my tests we decided it would be better to leave the settings for tools at its default and proceed with caution, after cutting out another classmate’s project however the Techno Isel CNC had some sort of problem leaving it stuck in demo mode.

I went back into Vectric Aspire yet again, this time to make 2 new toolpaths for our other CNC Router, the Laguna, which has a 4ft x 4ft working space. This smaller space is less efficient with material use it is much more accurate than the Techno Isel machine, which was greatly beneficial to my design once I had cut my pieces out. To assemble my cart I first started by going and marking each piece with where the squared edges should be, then I went into those spaces and filed the edges square once the edges were squared I decided to do a quick fit check to be sure my pieces were fitting together the way they should before moving forward.
My next step was to sand down all my pieces so they all have a smoother surface. Once the surfaces were smooth I applied 4 coats of satin finish polyurethane which I then buffed with steel wool to get my desired finish quality. Once my pieces were smoothed I began assembling my cart. This process went relatively quickly because I had already assembled it twice before once for the scale

prototype and once again when I had done a fit check. That is until I was down to my final two pieces, the back of my cart which holds everything together and the lower left floating shelf. The floating shelf was not fitting the way it had before the polyurethane coat because it now had less friction it did not want to stay in place so it could be attached. The back of the cart was difficult to get into place because the polyurethane had changed the tolerances ever so slightly for each of the points where it is supposed to connect. This lead to additional work needed to be done to file all the slots and pegs to adjust enough for each piece’s ever so slightly different positioning in relation to the back as well as the help from four other people to push the pieces into place.

If I were to do this project again I would push myself to ensure my design fit within a single board of plywood, because I really wanted my project to fit and had accounted for the surface area properly but not for the excess needed to cut between pieces. I would also choose to not coat the back with polyurethane until after assembly and would be more cautious of allowing polyurethane to get onto the joints.
This project taught me a lot about CNC routers and allowed me to build confidence with both of the machines available to me, it was also a great opportunity to work with a client and focus on the specific needs and criteria that client has. All that is left to complete this project is to reinforce the bottom of the cart because in attaching the wheels the hardware broke through to the other side. My goal is to complete this project before Christmas so I can bring it in to the classroom it was designed for before the end of this calendar year. Overall  I am really satisfied with my work on this project and am thrilled to have this piece to showcase both my abilities in CAD as well as my ability to operate a CNC Router accurately and effectively.