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Lab 1 - April 9, 2024
During Lab 1 we set up the solar panels and a previously made ISEC cooking from Nepal. As a group we discussed the optimal solar panel angle, cooking pot size, and how we wanted to move forward with the new design. We decided to focus our efforts on designing a 100 liter ISEC cooker for a school in Uganda. Along with increasing the pot size, we decided to experiment with a concrete cooking surface and lid. In the previous model, these elements were made from Aluminum which is not insulating the cooking pot enough. Because concrete is a less conductive material, it will keep the contents in the pot hotter, making the cooking process more efficient. Lastly, we started communications with Andrew, our collaborator for this project. Andrew was able to provide us with information about the project and what could be improved upon. Below is a photo of Kelly H, Aubrey Z, Theo B, and Pete during solar panel discussion.
Lab 2 - April 16, 2024
After getting a tour of the Mustang 60' Shop, we got our boots on the ground by experimenting with concrete. The concrete cooking surface and lid need to be roughly 2mm - 4mm thick so the plan was to try out different mesh options within the concrete. Although the concrete layer is quite thin, some kind of lath, mesh, or support is needed to ensure that the material doesn't crack. For this experiment we used fiberglass mesh and metal mesh. Our steps for this experiment are lined out below:
We mixed the concrete elements using a 1:3 ratio of Portland Cement and Sand (using gloves and masks for safety).
Slowly we added water while mixing the solution. Once the concrete reached a pancake batter like viscosity, we stopped adding water.
We cut out 3" by 3" pieces of fiberglass mesh. We kept one sample intact, pulled one sample apart so the gaps are roughly 1/8" apart, and pulled the strings out of the fiberglass to make supports roughly 1/2" apart for the last sample.
We cut out a section of the metal mesh.
Next we laid down a plastic bag on the surface. Using a metal cylinder (3" in diameter) as a template, we laid out 1.5mm of concrete. We added the mesh sample and then added another layer of concrete, also 1.5mm thick. We continued this process for all 4 samples.
We create one sample with no support using the same template and amount of concrete.
Once completed, we covered the samples in water and laid damp paper towels over all of them. We covered the experiment in another plastic trash bag to minimize moisture loss.
After completing the concrete experiment, we cleaned up the mess. With the remaining time we emailed Elwyn our community spokesperson. We inquired about more information about the school including: the school's cooking needs, the exact dimensions of the ISEC cooker, if we could place the pot into the ground, and if the school also wanted a 20 liter design as well. Next week we hope to get more information and to test out which concrete sample(s) was the most successful.
*Since Tuesday, we have made sure to check on the concrete samples, and add more water as needed.
Photos of this experiment are shown below.
Lab 3 - April 23, 2024
Our focus for Lab 3 was to test the concrete samples that we made last week and then create new samples based on the information we gathered. As mentioned in Lab 2, we periodically watered the concrete samples throughout the week and by the time we checked them during Lab 3, they were set and hard. At first contact, the sample with the intact fiberglass mesh delaminated instantly, as the concrete had no room to connect and solidify between the layer of support. We did not perform tests on this sample. Another item we noticed from the samples was that the side of the concrete that had been touching the plastic trash bag had a smoother and more ideal texture compared to the top surface. This is something we hope to achieve on both sides of the piece.
We tested the durability and success of the other 4 samples using the following steps.
We set up two steel members 2" apart and lay the circular concrete puck between it with equal spacing on either side.
Next we placed a metal cylinder (19 5/8" long ~7/8" in diameter ) in the center of the circle and placed a metal rod (24" long ~5/8" in diameter) in the center of the cylinder. We raised the rod so that it is 1/2" above the concrete sample and then dropped it. If there is no damage to the concrete sample, we continued testing drop heights in 1/2" increments.
We repeated this process for all 3 circular samples.
When testing the rectangular sample with metal mesh, we pulled the two steel members 3" and repeated the same process.
Our results from the test are as follows:
Circular concrete sample with no supports (3mm thick): Broke after 1" drop
Sample # 2 with fiberglass mesh pulled apart with roughly 1/8" gaps (3mm thick): Cracked after 2" drop, fully broke after 2.5" drop
Sample #3 with fiberglass mesh pulled apart with roughly 1/2" gaps (3mm thick): Broke after 1/2" drop
Sample #4 with metal mesh (1cm thick): Cracked after 9" drop, fully broke after 12" drop
Photos of this test are shown below.
After completing this test we deduced that the concrete sample with fiberglass meshed pulled apart roughly 1/8" as well as the concrete sample with metal mesh performed the best. In order to see the more accurate durability characteristics of each of these samples our next step was to create two larger samples of both with the same thickness and creation process. A goal of this next iteration was also to achieve a smoother surface so we planned to place plastic trash bags on both sides of the samples.
We carried out these next two iterations using the following steps:
We cut 2 7.5" circles out of a piece of wood. To complete this we used the drill press to create two holes in each circle and then the scroll saw to cut the circle shape out.
We sanded the circle pieces cut out of the wood so they were slightly smaller than the wood cut out.
Using the same process as Lab 2 we mixed the concrete elements using a 1:3 ratio of Portland Cement and Sand (using gloves and masks for safety). We slowly added water while mixing the solution. Once the concrete reached a pancake batter like viscosity, we stopped adding water.
Prior to creating the samples, we placed a plastic trash bag on the table, and pulled it taut using tape. We did this to avoid any creases in the surface of the concrete.
Next, we laid out ~4mm of concrete into the wood template. For one sample we then placed a sized piece of fiberglass mesh that was pulled 1.8" apart into the concrete sample, next laying another 4mm layer of concrete.
We completed this same process for the next sample, but with a sized piece of metal mesh in the center.
Lastly, we taped a section of the plastic trash bag onto the circle cut out and placed these onto the concrete samples. We then put weighted items down on both to minimize movement and ensure a smooth surface.
After completing the concrete experiment, we cleaned up the mess. We then discussed design options with Pete. Our goal for the Lab 4 is to see which sample is the most durable, continue contacting Andrew to see where we should direct our efforts, and to move forward with more aspects of the design.
Photos of the experiment are shown below.
Lab 4 - April 30, 2024
Our goals for Lab 4 were to discuss our next steps and begin to plan our final design goal(s). After discussion we decided to move forward with redesigning the ISEC cooker using concrete for the lid, cooking top surface (collar), and the pot holder. Using concrete will make the ISEC cooker much more efficient as it would conduct much less heat than the current design using aluminum. Concrete is also readily available inUganda which would make the replication process more streamlined.
After our discussion we moved forward with testing our larger concrete samples that we created in Lab 3. We periodically checked on these samples throughout the week, but we were not able to water them because the concrete was covered and pressed on all sides. At first glance, the concrete samples looked smoother than our first samples. We also noticed that the sample using metal mesh felt more durable than the sample using fiberglass mesh. Shown in the photos below, we were able to completely pull that sample apart after performing tests.
We tested the durability and success of both samples using the following steps:
We set up two wooden members roughly 5" apart and lay the circular concrete puck between it with equal spacing on either side.
Next we placed a metal cylinder (19 5/8" long ~7/8" in diameter ) in the center of the circle and placed a metal rod (24" long ~5/8" in diameter) in the center of the cylinder. We raised the rod so that it is 1/2" above the concrete sample and then dropped it. If there is no damage to the concrete sample, we continued testing drop heights in 1" increments. We changed these increments from the previous lab because the samples were thicker and larger in diameter.
We repeated this process for the other circular sample.
Our results from the test are as follows:
Circular concrete sample with fiberglass mesh supports (8mm thick): Broke after 7" drop
Circular concrete sample with metal mesh supports (8mm thick): No damage after 20" drop. There was a small crack on the back of the sample, but it did not reach the other side.
Next we wanted to make a small scaled test of the concrete collar as well as the pot holder. Based on the results from the sample test described above, we decided to try this next test with metal mesh. This continuous concrete piece would surround the cooking pot and act as a collar at the top surface. We carried out this next iteration using the following steps.
We cut a chunk of metal mesh to wrap around a metal cylinder 3" in diameter, creating a donut shape. The cylinder acted as a mold for the pot holder section.
We also cut a 7.5" section of the metal mesh, with a 3" circle cut out of the center. This acted as the support for the collar portion.
We tightly wrapped the metal cylinder in a piece of a plastic bag before placing the metal mesh around it as close to the cylinder surface as possible.
Following the same steps as the previous labs, we mixed the concrete elements using a 1:3 ratio of Portland Cement and Sand (using gloves and masks for safety).
Slowly we added water while mixing the solution. Once the concrete reached a pancake batter like viscosity, we stopped adding water.
Using the 7.5" wooden cutout template from the previous lab, we placed a 4mm thick layer of concrete leaving a 3" spaced circle in the middle.
Next we placed the donut shaped metal mesh onto this layer of concrete, before topping it with another 4mm layer.
We then placed the metal cylinder into the center of the template and began to wipe concrete onto the surface.
After creating the thickness layer of concrete we could, we covered the sample in a plastic trash bag to minimize moisture loss.
We are excited to find a better way to create the pot holder section of the concrete sample, as this technique made it difficult to create a consistent even layer. We plan to work through this failure during Lab 5.
Photos of this test are shown below.
Lab 5 - April 7, 2024
After completing our first attempt at the entire concrete piece in Lab 4, out goal for Lab 5 was to design a better suited mold for the concrete cast. Early in the day, we were able to meet with Elwyn, one of our coordinators. After discussing his goals for the school, we agreed (given the time left in the quarter) that we should focus our efforts on perfecting the design and construction of the concrete element of the ISEC cooker.
In the beginning of Lab 5, we checked out our lastest test from Lab 4. While the concrete dried and cured nicely, the test stuck to the sides of the wood cut out, making it almos impossible to remove the concrete from the mold. Futhermore, the metal cylinder we placed in the center was also adhered to the concrete, and was not budging. The plastic trash bag appeared to not have prevented adhesion between the concrete and the mold.
During the week prior Abe used a 3D printer to create a small prototype of a potential mold for the concrete. Both this and the concrete test from Lab 4 are shown below.
During the rest of out time during Lab 5, we completed several tasks. Abe and Theo worked on the newer and more improved 3D printed mold for the concrete. Based on Lab 4, we included the following changes
A handle in the cylinder insert to make it easier to remove
Two handles on the top surface piece to make the removal process easy
3 indents on the side of the mold for clamps to apply pressure to the concrete
Holes on the side of the mold for the wires to enter through
While constructing our last concrete test, we noticed at the metal mesh was hard to manipulate into the shape we wanted, so Aubrey went to home depot to buy chicken wire. The chicken wire she selected was a thinner metal gauge, a smaller gird, and more malleable. This will be very helpful during our next concrete test.
Lastly, Kelly worked on detailed drawings of where our concrete piece would be located within the ISEC cooker.
On Wednesday after Lab 5, Aubrey and Kelly were able to talk with Andrew one of our collaborators over zoom during a weekly meeting. Andrew informed us that the school has direct access to concrete, chicken wire, and a welding shop. This will be helpful if our final design of the concrete mold is made from aluminum or another metal. Andrew also told us that he ahs access to a UP Mini 2 ES 3D printer. All of this information was very helpful and will inform out final design decisions.
Lab 6 - May 14, 2024
For Lab 6 our goal was to test out the newest 3D mold. During the week prior, we printed out the 3D mold, photos of which are included below. Before we started our new concrete test, Abe was able to get the Lab 4 concrete test out of the mold, but during this process it was broken into several pieces because the concrete was so adhered to the plastic bag, metal cylinder, and the wood.
For the newest concrete test using the 3D printed mold, we followed the following steps.
Following the same steps as the previous labs, we mixed the concrete elements using a 1:3 ratio of Cement and Sand (using gloves and masks for safety). Since the Portland cement had run out we used Quikrete cement for this mixture.
Slowly we added water while mixing the solution. This week we kept the solution as dry as possible, to make the concrete set stronger.
Because the plastic bag did not hold as a barrier for the old mold, we decided to use duct tape this time. We placed pieces of duct tape on the male and female parts of the mold, as well as the cap.
Next, we rubbed motor oil all over the mold as suggested by Pete. This ensures that the concrete does not stick to anything.
Using wire cutters, we cut out chicken wire into the different pieces we needed: cylinder, bottom circle, and the collar. Something we noticed from the concrete test from Lab 5, was that the sample failed at the seam between the cylinder and the collar. To remedy this, we then used excess wire and strung the three pieces together to make the mesh as continuous as possible.
We placed one layer of concrete at the bottom of the mold and the collar. We then placed the chicken wire support system into the mold and began packing concrete onto the bottom and the walls.
Partially through this process we ran out of concrete and sand. Theo was able to bike on campus and grab us some from a nearby construction site.
After packing the sides, we placed the last part of the mold in and added one last layer of concrete to the collar.
To make sure that the sides of the mold had enough concrete, we took the end of a tip tie to push as much concrete as we could down the sides of the mold.
Before closing the mold shut with clamps, we watered the concrete.
During this process, we also placed concrete in the mini mold that Abe 3D printed. For these tests we only placed motor oil, and did not use supports as it is so small.
Later in the week, Theo went back and submerged the entire sample into water. He noticed that the water had significantly decreased when he went back the next day.
Lab 7 - May 21, 2024
In the very beginning of Lab 7, we checked out our concrete test from Lab 6, and it had completely failed. The concrete never dried or adhered to anything. Our initial thought was that because the mold was completely enclosed and submerged in water for several days, that the concrete never had a chance to dry. After discussion with Pete, he informed us that it may have been impurities with sand that Theo collected. Because we ran out of regular sand the week prior, Aubrey and Kelly went to get proper sand from home depot, to eliminate this problem for the next test. While Kelly and Aubrey were at Home Depot, Theo and Abe messed around with an aluminum pot and the chicken wire. Theo had the idea to attach cardboard to the aluminum pot for our final mock up in order to make the removal process more seamless. Abe was attempting to make the chicken wire mesh one continuous piece. Both of these are pictured below.
Before the Lab 7, our group discussed ideas about concrete and the other ISEC group informed us of some useful information. These notes are included below:
Metal mesh works well for supports. Galvanized steel is the best system because the coating adheres to the concrete nicely.
Rub down the concrete after it has had time to dry. This will make the concrete much stronger.
When creating a concrete mold, use one piece of the mold to form the shape and then rub it to increase shape and create a nice finish.
Our plan for Lab 7 was to implement some of these ideas into our next test. While our original plan was to use the aluminum pot as a one way mold, as described above, we really wanted to have a successful run with the mold from Lab 6, so we decided to focus our efforts there instead. We completed a test using the mold from lab 6 using the following steps.
Following the same steps as the previous labs, we mixed the concrete elements using a 1:3 ratio of Cement and Sand (using gloves and masks for safety). Different from Lab 6, we used Portland cement like all the other labs. This cement has given us the most amount of success.
Slowly we added water while mixing the solution. We did this until the consistency was slightly looser than Lab 6, but still quite dry.
We re-adjusted some of the duct tape in the mold to ensure that it was fully intact.
We then wiped the mold with motor oil to ensure that the test could be removed from the mold.
Just like Lab 6, we began with one layer of concrete at the bottom of the mold as well as the collar. We then placed the chicken wire mesh and started to pack the sides with concrete.
After the sides were covered with concrete, we placed the female part of the mold in and then added one last layer of concrete to the collar.
As mentioned in the notes above, our plan was to let this sit and then come back to work and rub the concrete. However, Abe brought a vibrating massage gun so we attempted to place this on the side of the mold to see if it would move the concrete and create a smooth surface. This was extremely successful as the vibrations pushed the concrete down into the sides and created a smooth surface by pulling the water to the top. We have included a video of this process. The tool was called a Hypervolt Massage Gun.
With our remaining concrete we used our old wood template and created two lid pieces. We used the massage gun on these pieces, but because the flat angle was awkward, it did not create the same result.
Because this last step was so successful we decided to not rub out the concrete, and let the smooth surface remain. The massage gun also brought a lot of bubbles to the surface which was a really good sign.
You tube links to massage gun videos
Entire Mold: https://youtube.com/shorts/WxQIGUVZNF4?feature=share
Lab 8 - May 28, 2024
This weeks lab was on a different schedule because of memorial day, so our meeting time was shorter than normal.
The first goal for this lab was to test out the different concrete lids we made the week prior. One sample was roughy 1 cm think with a smaller piece of chicjen wire, and the other sample was roughly 1.3 cm with a piece of chicken wire that covered the whole diameter of the concrete. The first sample had been left to cure without using the massage gun, and the second sample was vibrated with the massage gun.
We tested the durability and success of both samples using the following steps:
We set up two wooden members roughly 4" apart and lay the circular concrete lid on top it with equal spacing on either side.
Next we placed a ~ 24" PVC pipe on top of the sample in the center of the circle and placed a metal rod ~1" in diameter in the center of the lid. We raised the rod so that it is 1/2" above the concrete sample and then dropped it. If there is no damage to the concrete sample, we continued testing drop heights in 1" increments. We completed this process for the thinner un-vibrated sample.
We repeated this process for the thicker vibrated sample. As the test continued for this one, we increased the drop height increments to 4" to speed up the testing process.
Our results from the test are as follows:
Un-vibrated lid with smaller piece of chicken wire (1 cm thick): Broke into two pieces after 3" drop
Vibrated lid with larger piece of chicken wire (1.3 cm thick): Broke in the center after 24" drop
This informed us that having the chicken wire extend to the edges of the concrete as well as vibrating the concrete once placed in the mold, creates the strongest cured concrete.
The second goal for this lab was to try and remove our latest concrete test from the 3D printed mold. This immediately proved to be difficult as it would not bug with all of us trying to pull it. We attempted to clamp the mold down and pull on the handle inside but this was unsuccessful. We also used a hack saw to try and cut the pla which helped speed up the process. The finally removed the female part of the mold by using a dremel to cut and eventually peel away at the PLA. Unfortunately we were not able to remove the male part of the mold as it was fully adhered to the concrete. Our next attempt we plan to create a tapered mold to make the removal process easier.
Lab 9 - June 4, 2024
During the week between lab 8 and lab 9, Abe 3D printed a new mold that was the same as the previous print, but tapered. We made this change to hopefully make the removable process easier. Sadly, the female part of this mold failed in the printer and we were left with only the male version. With this in mind, our goal for this lab was to use the 3D printed mold to test out the taper as well as create a concrete pot holder and collar for an Theo's aluminum pot.
We completed these two items using the following steps:
Following the same steps as the previous labs, we mixed the concrete elements using a 1:3 ratio of Portand Cement and Sand (using gloves and masks for safety). We continued our use of Portand cement, as it has given us the most amount of success.
Slowly we added water while mixing the solution. We did this until the consistency was thick and moldable.
We cut two different pieces of chicken wire, one for the smaller 3D printed mold, and one for the aluminum pot. We also covered a ciruclar piece of plywood with duct tape and added a carboard moat to act as the female part of the mold that failed during the print.
We wrapped Theo's pot in layer of carboard, and then added a layer of duct tape to ensure the concrete wouldn't stick to the pot.
Next, following a similar process to the prior tests, we began placing concrete onto the sides of the molds making sure to smush it into the chicken wire. We applied several layers of concrete onto both molds to make sure there as enough on either side of the chicken wire.
To continue our testing with the massage gun, we attacked a nail to the end of the gun and placed it at the top of the larger mold. While this settled some of the concrete a at the top, it did not have the same affect as it did in lab 7.
Youtube Link to massage Gun with larger mold: https://youtube.com/shorts/Db3lrnbThjI?feature=shared
Also during lab 9, we ran a more controlled test with the massage gun. Using scrap pieces of plywood and acrylic, we created test chamber with two slots: a larger one for concrete with out mesh, and a thinner one for concrete with mesh. We then filled each side with concrete and placed the massage gun on the side of the chamber. When we placed the massage gun on the side with no mesh, a few bubbles rose to the top but not much change happened. Since the gap was so large, the concrete had time to settle and didn't need to vibration assistance as much. When we placed the vibrating on the side with mesh, it instantly helped to push the concrete deeper into the chamber. Before using the massage gun, the chamber looked full, but after the vibrations there was much more room for concrete.
Our findings are as follows:
The massage gun works best with a thinner chamber. When the chamber is larger, the concrete has more room to settle.
The massage gun helps move the concrete down the sides of the mold allowing for more concrete. This ultimately creates a stronger cure and adhesion to the chicken wire.
Youtube Link to concrete test chamber: https://youtube.com/shorts/X6Gc_8df6Ys?feature=share
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