This is the last week before the Science Fair, and it’s getting real! At first we were waiting for the experts at the Applied Labs to finish with the electronics so we decided to start working on the column for the sculpture. After a lot of driving around town to get everything we needed, we could finally start building.
We found it to be very easy to build the column and we had very little complications. But our estimation that we would only need half a day to build was very wrong, since we had to work on it for another day.
The plastic extruder was ready just in time for us to start working on the sculpture. We tested the extruder and the moment the plastic started flowing out of the extruder was a very exciting moment, all the hard work was finally paying off!
We had made a sketch earlier of what we wanted the sculpture to look like and we began with our first attempt to make the sculpture. The first thing we noticed was that it was not that easy to see what you are doing when holding the extruder. The second thing that we noticed was that the extruded plastic would break off right away and it was impossible to extrude vertically. After trying several times with different types of support we realized that our idea to extrude vertically into the air would not work. That is when we decided to put the extruder down, and use a large piece of triplex to catch the extruded plastic, this way the plastic would not break off due to gravity. At this point we also noticed that the drill that we used as the motor for the extruder was not strong enough to handle the large amount of torque needed, so we switched to using a handle to make the extruder hand-driven. We extruded straight pieces onto the triplex and we went over it several times so that it would be several strings of plastic stuck to each other instead of just one. After this we heated up the strings with a heat gun, so we could easily manipulate them and bend them around the column. We drilled holes in the shelves of the column and used wire to attach the strings to the shelves. We just kept repeating this process until the whole sculpture was built! Even though the sculpture did not look exactly like what we had envisioned, we were very happy with it and proud of it!
This week our objective was to build a prototype of the plastic extruder for initial testing. Last week we disassembled an old extruder and we are using some of its parts to build a new one. During the building of we discovered several problems which we solved with some creative thinking. The first problem we encountered was with collecting the parts we needed for the prototype. Since we did not have these parts yet and we did not know exactly how big they would be, it was hard to envision what the prototype would finally look like. So we decided to work on the front of the extruder (the nozzle part) in the meantime until we get the parts that we need for the rest of the extruder.
Since our plan is to experiment with nozzles of different sizes we decided to create a ring that would fit around the nozzles. We would then tap a screw thread in this ring so we can screw it on the extruder and remove it easily. This way we can easily change between nozzles without having to tap screw threads on all of the nozzles.
Our initial plan was to tap a screw thread around the end of the extruder, but we found out that this would be impossible since the tube is way too thin. We decided to make a thicker extension for it, that way we can tap the extension. We will later create the ring to fit this extension.
Below you can see the tube with its extension:
After this we decided to place the nozzle inside of the tube instead of on top for better heat transfer.
This week we also played with the table version of the extruder to see what the material (PLA) looks like when it is melted. This was also our first attempt at finding the optimal temperature for working with the melted PLA.
We also had a meeting with Casper van der Meer, project manager of Perpetual Plastic Project. He provided us with a lot of insight into the building of the prototype and also working with plastic. First he suggested that if we wanted to make the extruded plastic look more consistent we would have to focus on the plastic when it has already been extruded and it is drying, instead of when it is still in the tube. He suggested using air or water to dry the plastic faster, that way we will be able to build on top of the already solidified plastic.
He also pointed out that we would have to pay a lot of attention to safety since the machine will get very hot, insulation will be very important. We also talked about the fact that we wanted to make the machine hand-held, but it will probably be very heavy. So we will have to think of ways to support the machine to help the user.
Finally we talked about the parts that we still needed to finish the prototype. Some parts will be given to us by Casper, and some parts will be ordered online. Hopefully next week we will have all of the parts so we can continue to build the prototype. Stay tuned!