H2C – Experimental mixed nozzle diameters in a single print (0.4 mm / 0.8 mm)

Bambu Lab H2 Series
1

Hello,

I wanted to document an experiment carried out on a Bambu Lab H2C using two different nozzle diameters in the same print job.

The objective was to test whether a print could start with a 0.4 mm nozzle and then continue with a 0.8 mm nozzle, while preserving the native H2C tool-change sequence generated by Bambu Studio.

For the first test, two cubes were placed side by side:

  • Right hotend: 0.4 mm nozzle, PLA
  • Left hotend: 0.8 mm nozzle, PETG

Separate G-code files were generated for each nozzle size.

A third standard dual-hotend file, using a supported configuration, was used to recover the native H2C tool-change sequence.

A hybrid .gcode.3mf was then assembled while keeping the original H2C initialization, tool-change and firmware commands.

During the print, the H2C displayed a warning indicating that the hotend configuration did not match the expected configuration, but the printer allowed the print to continue.

The machine then:

  • initialized and calibrated normally;
  • selected the 0.4 mm right hotend;
  • purged the PLA;
  • performed nozzle-offset calibration and the normal startup sequence;
  • performed bed leveling once;
  • printed the first cube with the 0.4 mm nozzle;
  • changed automatically to the left hotend;
  • loaded and purged the PETG;
  • printed the second cube with the 0.8 mm nozzle at the expected position.

The second cube was printed correctly next to the first one.

This test suggests that the H2C firmware is capable of executing a print using two different nozzle diameters, provided that the native H2C tool-change workflow is preserved.

This is not a supported Bambu Studio workflow. It is only an experimental test at this stage.

The next step will be to test a more practical use case: printing fine details with the 0.4 mm nozzle for the first few layers, then switching to the 0.8 mm nozzle to print the surrounding geometry and continue the rest of the part.

The hybrid .gcode.3mf used for this test is attached below.

Important: this file was generated specifically for this H2C configuration and should be considered experimental. Please verify nozzle positions and configuration before attempting to print it.

I will update this thread with the next test results.

image
image912×598 94.1 KB

H2C_test_mixte_04_droite_08_gauche_UN_NIVELLEMENT.gcode.3mf (54,4 Ko)

2

A bit on/off-topic… The two tool changes on every layer will invalidate any time savings of using a larger nozzle unless is a very big item. Also you can change the line width to 0.8mm for infill for example and print 0.4mm walls and 0.8mm infill with a 0.4mm nozzle.

3

Thanks — the actual use case is a bit different from the two-cube test.

I am trying to improve the surface/detail quality of parts that are produced repeatedly. The idea is to print a small detailed insert first with the 0.4 mm nozzle, about 0.62 mm thick, and then switch only once to the 0.8 mm nozzle.

The 0.8 mm nozzle would then print the material around the insert and above it, and complete the rest of the part.

So the intended workflow is not repeated tool changes on every layer. It is more like:
0.4 mm detailed insert → one tool change → 0.8 mm surrounding geometry + rest of the part.

The two-cube test was only a simple way to verify that the H2C firmware could handle a mixed 0.4 / 0.8 mm job at all. The next test will be the real geometry: a 0.4 mm insert embedded into a part otherwise printed with the 0.8 mm nozzle.

4

Im pretty sure bambu are working on implementing this, especially now that creality has mentioned using two different nozzle sizes in one print in their marketing materials for KliTek. So its just a matter of time before this is available in BS.

5

Prusaslicer 3 will have dual nozzle size option also. Unfortunately only one layer height for all, for as far as I understood.

6

I dabbled a bit in dual nozzle size printing but unfortunately, I have not found the time to continue since then.
Still, the trials I uploaded upon request and the linked forum entries may be of interest to you.

Very much looking forward to following this thread and of course a Studio release based on PrusaSlicer 3 (whenever that may be).

:four_leaf_clover: & :crossed_fingers:

7

Hopefully soon, I like the way they implemented the custom settings for each nozzle/color.

Also the way they allow jobs going over multiple printer types.