Author: GizNews

The Bambu Lab X2D’s tool head, featuring two distinct nozzles, was already explored in a comprehensive examination. Now, lets put that idea back into the bigger picture of 3D printing. Essentially, this is about multi-filament printing – making different colours or types of filament in one single run. Cheaper printers can do this too. The basic concept is simple: The filament gets cut, the old stuff is pulled out of the tube feeders by a filament dryer that also feeds, and then new material is pushed into the extruder.

How a 3D Printer Actually Works

At this stage, we need a brief detour into how 3D printers generally operate. We will keep it deliberately simple and somewhat model-like, not too technical. A 3D printer doesn’t sit still in a static balance; it moves in flow. It’s a dynamic system that needs time to settle after turning it on or when temperature or material conditions shift. Think of a garden hose, where you only get a steady stream a little while after opening the tap, and you sometimes have to twist the nozzle to make the jet better.

Priming vs. Purging Explained

The hot end goes through a start-up phase. After heating, there is a brief priming period where filament continuously reaches the hot end and the melt and pressure conditions stabilize; only then does extrusion become repeatable. Priming is different from purging. Purging is always needed when you change filament because the molten material already inside the hot end cannot be removed just by retracting it. In the photos, you can see the change between grey and white in the filament droplet during this middle phase. This difference between priming and purging is also fundamentally important for the X2D.

It is this exact difference between priming and purging that matters with the X2D. Purging can be skipped completely, but priming cannot, because only one print nozzle can work at a time. In our test with the Multicolor-3D-Benchy from 3Designs, the X2D shows it is clearly better when both nozzles are used. If both nozzles are used, the 12-gram model only creates around 20 grams of waste, which is almost all from the purging tower. If only one nozzle is used and the filament has to be changed and the nozzle flushed repeatedly, about 70 grams of waste is made for every 12 grams of the real model – 52 grams are from flushing.

Print Time and Waste Numbers

This also fully hits the printing time. With just one nozzle, the printing time goes up from 2.7 to 5.8 hours. Two things to keep in mind: We used standard settings and the actual numbers likely depend a lot on the specific model being printed. The logical question is whether you can skip the priming process. If you could, the priming tower would not be needed and the printing time would drop to just 1.7 hours when using both nozzles.

Should You Skip Priming?

In our test, skipping priming didn’t make sense. Bambu Lab correctly advises against it, because it causes a big drop in print quality. Printing without priming would likely need systems with two fully independent tool heads – a specialist solution. Beyond saving material, two nozzles open up other options. For instance, printing support structures in a different material lets you use cheaper filament for supports. The PVA sold by Bambu Lab (meant for supports) is not cheap. The trick is that PVA is water-soluble, so support structures dissolve in a water bath instead of being removed by hand. That is also best seen as a specialist case.

Does the X2D allow multi-material printing with no waste? No. That shortfall is not really due to the machine itself but more to the underlying technology. Still, waste can be cut down a lot and print time shortened, so the multi-nozzle system is both useful and efficient. As shown in the review, using both nozzles does not necessarily lower print quality – parts can still look like they were made as one single piece. The fact that the second nozzle does not support TPU and has a lower maximum speed, for example, was not a big limitation in practice. Setting up two-nozzle prints in the software is very easy, and the software suggests sensible groupings.