Well the experiment did not fail, but it sure did not provide the desired results. “An absolute mess” it has been called, but from the gooey remains of our set up we have build the foundations of our new set up.
So what happened? Our initial UltiCast fears were confirmed when we tried to cast the silicons in our first full scale test. Due to the high viscosity (18,000 cps) of our silicon components, we had a huge pressure buildup when trying to use the second extruder. In reality we tried to push molten chocolate through a 1 meter flexible tube with a diameter of 4 millimeters, but you could imagine it to be like pushing wet concrete through a garden hose.
Needless to say soon we were all covered in silicons. Our tubes had burst under the pressure that was being build up. Due to a then discovered syringe flaw that lead us unable to retract the plunger and release the pressure from the tube, we discovered that the only thing we had created was a ticking silicon bomb. Luckily the silicons are skin safe so the damage was contained to a bit of clean up.
To counter these problems we have redesigned the UltiCast set up. First of all we now use bigger tubes and static mixing nozzles to reduce the friction created by the highly viscous silicon components. We have tried mixing the silicons in these wider pipes and they proved very successful.
.To be able to reduce the pressure on the pipes if needed, we have remodeled a part on the plunger to enable it to retract. This part still has to be tested in a full scale test, but also seems to be functioning correctly.
We are currently waiting for our final components to finish printing so we can do a second cast with UltiCast.