Jace Aschbrenner Final Portfolio: Charred Chess Board and 3D Printed Shoe Midsole

Hello everyone! This has been a great class, and these two projects were awesome experiences.

For my upcycle project, I created a rustic shou sugi ban chess board. The rustic nature of this chess board gives way to a natural, stripped, and simple design. Shou sugi ban refers to charring wood to acquire new coloration, and also structural integrity. The burned wood grains turn black during charring, but also strengthen the wood as a whole. For this project, I used alternating levels of char on different components to achieve light and dark squares and borders. This allowed me to refrain from using any stains or paints to achieve my desired colors in the board, thereby adding to the rustic effect as well.

I took inspiration for this project from my fondness of chess, a game I played a lot last summer, and the love of the mountains and my friend’s ranch up in Kremmling, CO. I became pretty adept at chess last summer, but it becomes pretty meaningless when all of the opponents are random online players.

My friend Tyler has a family-owned ranch in the mountains, and although I have only been there once, it’s already had a pretty big impact on my life. My last woodshop project was a laser cut wooden board made from Tyler’s barn wood, and I used it to propose to my now fiancée Lexi! I also attended Tyler’s own wedding on the ranch, and plan to have my bachelor party there at their Air BnB as well! This chess board just feels like an extension of these connections, and it felt like an easy decision to utilize the barn wood from the ranch.

The first part of the design process was to dimension the board and cut the wood. Initially, I wanted to create a sixteen by sixteen inch board, including two inch borders around the squares, making a board of one square foot (1.5″ squares). The board I received was about three feet long and fifteen inches wide, and substantially bowed and cracked. Therefore, I had to shrink my overall dimension to a single square foot with an eight by eight inch square for the playing space. I then cut a twelve by twelve inch base board, two inch borders, and about 72 one inch squares.

The next step was to char the wood in line with the shou sugi ban aesthetic. To do this, I purchased a simple blowtorch from Home Depot. I am aware that CU Boulder wood shops provide these, but this was a fun personal purchase. I then went outside into my snow-covered backyard, and began charring the dark pieces of wood to a deep black, and the light ones to a nice speckled grain pattern. This ended up being a rather difficult process to get my torch to light with the wind compounding the difficulty of the badly-built ignition, but I managed to get it working after about half an hour. I actually had a few issues where I set the wood on fire, rather than charring it, but it was always on the darker pieces, so the parts were not compromised.

After all the components were appropriately charred, I then went over to my workplace, Lever Movement, to use their drills and mallets with my wood components and wood screws. I first used calipers to mark out two inch rows on the edges of the back side of the board, and then lined up one border at a time with supports underneath the base board, and screwed each border piece in with three screws. I had dimensioned these pieces earlier to border an exact twelve inch square, and something I found out after the fact is that the bow in the base board makes my base surface longer than twelve inches. While this does add to the rustic aesthetic, I do feel that I could have fixed this by measuring the base board surface, rather than assuming it was twelve inches, and then cut the smaller borders to length. Once the borders had been screwed in, I then worked to place 64 checkered squares in the space in the middle. These squares ended up being a very nice press fit, and I was able to secure the board construction completely without glue or screws, which honors the rugged simplicity of the rustic aesthetic. An added touch to this is that I made sure that the grains of the white and dark squares were perpendicular to each other, which helps to differentiate them from each other. I had extra wood screws and a polyurethane finish prepared to secure the squares and finish the wood surface, but I felt that these additions would detract from the simplicity of my design.

For future improvements for this project, I first could make the board bigger and up to my original specifications by making it foldable so that the pieces could be cut from the provided barn wood. However, I personally think that the coolest possible addition to this project would be to go look for antler pieces or natural components on a hike in the mountains that could be attached to the borders of the chess board. This would give the build a much more decorative and natural element, while maintaining the simple, rustic aesthetic. Lastly, I want to buy unfinished wood pieces for this board specifically, and char them in a similar fashion to the board to complete this as a usable, decorative chess board that I can keep and use for years to come!

This is a link to a video of my charring process!


For my main design project, I wanted to investigate how plastic could be structured to resemble foam in its mechanical properties. Plastic, especially 3D printing thermoplastic like TPU, is more sustainable and recyclable than foam, and can also be printed in unique structures that have cool aesthetics.

I made a 3D printed running shoe midsole for this project.

Version 1 of my Gyroid Infill Midsole

I tested seven TPU plastic blocks with different gyroid infill densities to see which one most resembled the foam of a shoe. After polling my cross country team members, I was able to select an infill density with reasonable accuracy. Last week, I submitted my initial computer design model to Patrick Maguire at the Idea Forge. This initial model included a right and left shoe, at what I thought was a men’s size 11.5 shoe. He got back to me before printing, saying that the bed size of the 3D printer I was using was too small for my model. To fix this, I modeled just a right-side midsole, and asked if he could print on a diagonal in the horizontal and vertical directions. This orientation allowed the model to fit on the smaller Prusa MK4 printing bed, although I did have to pay more for support material.

The print in progress at the Idea Forge.

This print took a long time, and I was able to check on it periodically over the course of two school days. While the model was able to fit on the bed, the vertical diagonal was approximately a forty five degree angle, which impacted the print’s adhesion to the support material and overall stability of the part. I believe that this angle also impacted the aesthetic appeal of the outside of the shoe midsole, which looked a little messy and melted by the time the print was complete. Lastly, this angle had a substantial impact on the base shell layers, because the slicer had trouble understanding where the base of the model was with the new angle adjustment.

Once I picked up the print, I immediately realized that I made an error in sizing. My CAD model measurements were to the outside edges of a more “flamboyant” shoe with a large heel flare, and my measurements did not adjust for that. Because of this, my shoe has the width of a men’s 11.5 shoe, but the length of about a men’s size 13. Other than this error, I was generally happy with the sizing of the shoe.

My 11.5 foot on what I thought was an 11.5 midsole!

I did multiple pressure tests on the shoe by stepping on it stationary, walking over the part, and jumping on it. These tests showed that the plastic responds in a very similar way to foam in normal running shoes, but TPU plastic does not have great elastomeric effects, and so the midsole was not as responsive as more high quality running shoes.

My CAD Model For Printing

For the continuation of this project, I am going to re-size the shoe to better fit my men’s 11.5 foot, and look to re-print with the Idea Forge. Hopefully this size change will make it substantially easier to print on the Prusa printers. Once the 3D print has been sized, I can fit it with an insole and begin designing an upper!

Shoe upper inspiration! From AliBaba


Previous posts were utilized for this portfolio.

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My Portfolio – Nick Olguin
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Post 13 – Project Portfolio

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