It took some time to get back to my “Showplanes Cowl with A/C left hand inlet plenum problem”, but this week I finally unleashed my new 3D printer on the problem, and the result was great.
This is a complex part, and I evaluated several different slicing applications to figure out how to do the necessary support structures. I wound up using Cura, because of its “Tree” support capabilities. It generates all sorts of weird tree trunk/branch constructs to support the part while it is being printed. This results in less interference between the support and the part.
It took 4 days 16 hours to print the part in ASA, using a bed temperature of 100 deg C and a 0.4mm nozzle at 250 deg C. I did gear up to use a dissolve-able filament (HIPS) between the support and the part, but decided for the first trial to simply use the one extruder. As it turned out, the support was easy to rip away with a pair of pliers, so I’ll stick with the single material process to save time and complexity.
There were a few areas where the support came slightly adrift, causing rough regions on the part. I need to fix this by manipulating the support to have better adhesion to the bed. It takes about 5 hours to render the model, another hour or so to “repair” the STL, and about an hour to slice the result and generate gcode for the printer. Although the part as printed is certainly usable, there are areas I can improve on. Since each printed part is a 5 day exercise from start to finish, and comes with a filament cost, I won’t be spinning revisions too often.
There are some new materials around, Polyamide with Carbon Fiber filler, which are stronger and have higher operating temperatures, up to 180 degrees C. I can print these materials if I install a hardened nozzle on the printer, but I’ll hold off on this until late in the build because the filament is expensive, and there are new products hitting the market all the time.
For now, I have the entire process under my own control and I’ve been able to print a perfectly acceptable part – mission accomplished for the inlet plenum, finally. Now I can finish the front baffles in this area.
How many hours have I spent on this? A lot, between assembling the printer from parts, calibration, printing test parts, evaluating slicer software and monitoring the printing of the plenum. None of this is really direct work on the air frame, so I’m going to simply log 1 hour for this activity, knowing full well that it was many times this.
