Archive for May 2009
Lastnight I went to NYC Resistor and we got the printed plastruder plastruding. This should allow more people to create new extruder designs now that only a 3D printer is needed rather than a laser cutter. The future amazes me every day.
Today we finished printing the plastruder on the Dimension BST. Some of the holes were a little too small and the distance between the retaining screw holes was off. Matt fixed the 3D model and the files should be on Thingiverse soon. Well done, Matt!
I don’t have a frostruder myself, but have learned a few things from those who do. Aparently, one problem is that the frosting continues to extrude after there is no longer force being exerted on the plunger syringe. One idea is that there were air bubbles in the syringe from loading the frosting and the solution is to be better at packing.
I wanted to give it a try, so I removed the plunger from a syringe loaded it by vacuuming through the nozzle with a pump. The loading process went perfectly and there were no bubbles to speak of. I gave the plunger a push and out came some frosting. Success! Well, not really. After I stopped pressing the frosting continued to extrude. Why?
The frosting itself must be compressable! This makes sense since the frosting is a bunch of ingredients whipped and mixed together.
I then set up an experiment to observe the effects of air within the frosting in which one glob of frosting would be placed in an evacuated chamber while another would remain at 1 atmosphere of pressure (first image).
After the chamber was evacuated I could see that the test glob had expanded (second image), presumably from air within the frosting. The test glob collapsed as it was brought back to 1 atmosphere of pressure (third image).
I feel this supports the idea that air within frosting causes continued extrusion.
. A valve at the end on the frostruder to regulate frosting extrusion.
. Find an incompressable frosting-like material.
. Don’t use a plunger. Pump air behind the frosting and return it to 1 atmosphere when the frosting should stop extruding.
. Pull the plunger back to bring the pressure withing the syringe to 1 atmosphere.
Matt, a member of the Technology High School robotics team and Thingiverse contributor has been working on a 3D-printable extruder for the Makerbot Cupcake CNC.
In the first image you can see him working on the 3D model in Autodesk Inventor. There didn’t seem to be a way to import the DXF files into Inventor, so Matt laboriously made measurements from the DXF files in another application to draw a new 3D model.
On Wednesday (13 May 2009) the resulting STL was loaded onto our Dimension BST and began a four hour print (second image). The next day we had ourselves a printed plastruder body. There were a few small errors, but it sure is beautiful (third image)!
Matt and Mr. Sylvester (our robotics teacher and resident machine shop wizard) discovered a process to import a DXF into Inventor and extrude it upward to create a 3D model. He pretty much just leveled up his productivity and said his goal is to put one cool thing on Thingiverse each week.
On Friday Matt started creating a new 3D model directly from the DXF files. The design will use holes tapped by the user rather than embedded nuts. We should have a printed head early this week. Possibly even printable repacements fore the big and little dino brackets. This would remove the need for any laser cut parts and thus the less-than-fun experience of peeling the protective layer from both sides of each laser cut piece.