A short story of a typical 3D printing failure…

For some time we have had the pleasure of testing one of the leading Polish machines of the low-cost 3D printers market – the HBOT 3D of the 3D Printers from Wroclaw. Its greatest advantage is a very large build size of 30 x 30 x 30 cm. With so much space, you may not only print several elements simultaneously, but above all, make really big things. This, however, requires very long operation time, often more than a whole day. To check the performance and the reliability of HBOT, as a part of the tests we decided to print something remarkably large, which would take a sufficiently large amount of time. In addition, we wanted the printout to be appropriately pleasing to the eye. Our choice was a model of a very shapely woman, which we found on Thingiverse. The 3D printing began on Monday morning and ended on Wednesday at night. It was not one hundred percent successful, unfortunately… As usual in such cases, it was the human factor that failed. Here is a brief but instructive story of a very long printout whose final effect was spoiled by the filament improperly wound on the roll. On top of that, we were the ones who wound it…

To start with, let me just say that several dozen-hour printouts are very stressful. When the first dozen hours of 3D printing pass and 2/3 of the filament roll is spent, the awareness that something may go wrong at any time – or, for example, a power failure may occur, awakens very strong emotions. When you come to the office in the morning and see that is still printing, the filament did not run out yet and all in all it looks as it should, relief is washing over you like tropical rain. On the other hand, to see the finished printout that looks like the picture below is extremely frustrating…

Let us start from the beginning then. We used the two half-kilogram PLA rolls by Noviplast which we received from Get3D. It was a test material and this time it was wound up in rolls. Before we started working, we rewound it manually onto empty spools. Winding the filament is an activity that slowly fades into history. Some time ago if you wanted to buy cheap plastic there was no other choice, because it was only sold in rolls. Today, it only applies to certain filament types or some really cheap solutions. As for the good PLA or ABS plastic, it is nowadays already wound onto spools.

Anyway, we started printing. The first half a kilo of orange PLA run out in the twenty-seventh hour of printing and we were forced to replace it on the fly (HBOT is so far not equipped with filament replacement option in its firmware – although the printing may paused, the head remains over the printout, in the place where the operation of the device was suspended). Although sweat poured down our forehead and our hands shook a little, the whole operation was finished without the slightest problem.

When it seemed that everything was heading towards a happy ending, our lack of experience in manual filament rewinding had a grim finale. Wednesday morning when I came into the office, the print had already been finished, but the top of the model’s head was not printed. I performed a brief yet intensive investigation that resulted in the discovery that the filament on the roll was jammed in a tangle of loops, the 3D printer’s extruder not being able to pull it any further, carved a hole in it with the knurling wheel, effectively preventing its further extrusion.

The end result was exactly the same as in a similar story, which I described a few months ago, when fifteen minutes before the end of a dozen-hour print the last filament I had run out, leaving an identical hole in the model’s head.

This time, however, I did not intend to give up – we had already used more than a kilogram of filament, 40 hours of machine operation, and above all we had so far a pretty cool model. From the very beginning we planned to process and paint it properly (like we did once with the famous head of Ewa), so we did not pay attention to the variety of colors from which it had been printed so far. However, the failure with the head was quite a considerable shortcoming. At the beginning we tried to find a hat on Thingiverse, but in the end the two variants that we tested did not turn out to be interesting. Therefore, we asked for the help of fellow printers from Combi 3D – Maciek Dobrowolski and Tomasz Filipek, who conduct 3D printing trainings with us.

Maciek and Tomek first pulled the exact size and scale out of the Gcode of the printed model and then determined exactly when the printing was interrupted. Using Netfabb they cut off the missing piece of the head and sent it to us in the form of an independent STL file. The top of the head was printed on Monkeyfab PRIME (the Hbot was already printing another long printout) and glued to the existing model. Then we had some precise processing and painting to do (including resin XTC-3D coating). We will not fail to boast with the final result, of course 🙂

There are two conclusions to this whole story: first, we should not undertake to do things we know nothing about (see the manual winding of the filament), as the results can be very disappointing. Second, the 3D printing always leaves us with a way out of the situation and a second chance. Regardless of where the printing is interrupted, there is always a possibility to complete it at a later time.

Source: centrumdruku3d.pl