• Jon

How to 3D Print an Aeroplane - Day 17 - Making Test Parts and Some Early Print Troubles

The fuselage and empennage are printed, with no major issues. The long, relatively thin tail booms survived the print with only low levels of distortion at the higher z values. For these parts, and the small fiddly parts I used a brim for the surface adhesion and this held them nicely to the print bed and provided enough support to stop them being knocked over.


The only reason for printing in this order is to save me changing out the filament as I wanted the fuselage, tail booms and fins to be the same colour. Next, it's time to move on to the wings. Below is the wing central section, you can see that it has a fairly long print time. At the top of the part is the slot for a servo. What I don't want to happen is to find out in 9 hours that the measurements are not quite right, or the print tolerance, messes up the measurements.


The solution, print a test piece. This way you only lose an hour and waste a small amount of material if you find the gap is too tight. You can do this by simply moving the model in Cura to just print the top, this might be the best method depending on your model. For this part though you can cut down the print time further by cutting the section out in Fusion 360. I'll show you how in the screen cast just below.





After a 35 minute print I can check the fit with the servo. Looks good, so we are ready to go with the first print of the centre wing section.


Unfortunately...

On checking the first few layers of the print I found it was suffering some epic under extrusion. First off I wondered if the change of PLA was the problem so I made there shell thickness 0.5mm to see it that fixed it. The next print was even worse. If your new to 3D printing this is an important lesson to learn, always check the first few layers of your print.


Cue 1 hour of troubleshooting. I nailed the problem down to a sticky section in the end of the Bowden tube to the extruder. This was causing the filament to hit a section of resistance so the stepper motor was struggling to push the filament through.. I think hot PLA has been pulled back into the extruder when changing filament and this might have been the problem. I switched the Bowden tube out which solved the problem.


The wing pice printed nicely. Annoyingly Cura (me) placed the seem on top of the aerofoil which left an unsightly mark. A quick look in the settings and placing the z-seam on the sharpest edge solved the problem. The second opposite side piece was printing beautifully until a tangle in the filament spool put an end to that print.


Its annoying but that is 3D printing - it's like using a inkjet circa. 1990. What do you mean you can't find the printer, it's right THERE!!



First print with z-seam onto of aerofoil.

Second print with re-positioned z-seam on right.

Both pieces together.

 
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