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!