The H2S is the single-nozzle version of Bambu’s H2 platform: same 340 x 320 x 340 mm build volume, same actively heated chamber, same CoreXY motion, minus the second toolhead the H2D carries. That single-nozzle layout actually simplifies the first print compared to its sibling. There’s no filament-to-hotend matching step to worry about. You load one nozzle, pick a file, and go.
Picking Something to Print First
You have two practical starting points. The H2S ships with pre-sliced models stored in its internal memory (a dual-color top or similar demo piece is typical), so you can print directly from the touchscreen without touching Bambu Studio at all. If you’d rather slice something yourself, a Benchy or another small calibration-style model is a reasonable first choice: fast to print, easy to judge with your eyes once it’s done.
Either way, keep a USB drive plugged in if you want time-lapse recording or the option to send files over the local network. It isn’t required to print, since the printer has its own onboard storage, but you lose those extras without it.
Starting the Print From the Touchscreen
With AMS filament, load a spool, let the printer read the RFID tag, and confirm the material and color match on screen. With an external spool, insert the filament until the toolhead’s indicator light turns green, then use Edit to set the filament type before tapping Load. The nozzle heats and starts feeding automatically; you’ll see filament extrude once it’s loaded correctly.
From there, tap Print Files, choose your model, confirm the build plate type matches what the slice expects, and tap the confirm button to start.
Starting the Print From Bambu Studio
Import or open your model, slice it, and click Print Plate. A window opens to confirm the target printer and the filament assigned to the job before it’s sent, either directly over the network or through Bambu’s cloud, depending on how you’ve added the printer in Studio.
What the Pre-Print Calibration Actually Checks
Before the nozzle touches the plate, the H2S runs Auto Bed Leveling by default. It’s a toggle in the print job window (also available under Advanced Options on the touchscreen), and Bambu describes it as a comparatively quick pass, distinct from the longer Auto Bed Leveling and High-Temperature Bed Leveling routines you run manually from Settings > Calibration > Print Calibration. The quick version reads bed height and blends that with whatever full calibration data is already stored on the printer.
High-Temperature Bed Leveling isn’t forced on you before every job. It’s meant to be run separately before printing warp-prone engineering filaments like ABS, ASA, PC, or PA, since it takes more measurement points at operating temperature. If you’re starting with PLA or PETG, the standard Auto Bed Leveling pass is what runs. Other calibration options in that same menu (motor noise cancellation, vibration compensation, motion accuracy calibration) exist for tuning print quality over time; they aren’t part of the automatic per-job sequence and don’t need to be run for a first print.
None of this replaces watching the actual first layer. Bed leveling catches height inconsistency across the plate; it does nothing about a dirty build plate, the wrong bed temperature for your material, or filament that’s absorbed moisture sitting out.
Chamber Preheat and the First Layer
The H2S chamber is actively heated with a PTC element and circulation fan, rated up to 65°C, and it matters for materials like ABS, ASA, PC, or PA that are prone to warping if the chamber isn’t warm enough before printing starts. When a slicer profile calls for chamber heat, the printer switches into heating mode: the automatic exhaust grille and intake vent close to hold heat in, the PTC heater runs at full power with the circulation fan at full speed, and once the chamber reaches its target, the fan holds steady while PTC power backs off to maintain temperature.
Owners of H2-series printers have reported the machine sitting at the start of a job with a "waiting for chamber to heat" message when a print calls for chamber heat, which suggests it holds off starting the first layer until the chamber gets close to target rather than heating as it goes. If you’re printing PLA or another material that doesn’t need chamber heat, this step is skipped entirely and the chamber stays unheated with the fans in cooling mode. If your first print is an engineering filament, budget a few extra minutes before the nozzle actually starts moving.
What the Cameras and Lidar Are Watching For
The H2S carries three separate sets of eyes, and they don’t all do the same job. The toolhead camera and Micro Lidar handle calibration: motion accuracy, build plate positioning, and flow-related measurements that happen before and during the print but aren’t about judging what the print looks like. A separate chamber-mounted camera (Bambu calls it the live view camera) is what actually watches the print itself.
That chamber camera does several things during the first layer and beyond. It checks that the build plate installed matches what the slice file expects, scans for foreign objects left on the bed before the job starts (up to two checks, once before the bed lifts and once after), and once printing is underway, watches for spaghetti (filament detached from the model and piled up), pile-up around the purge area, and visible clumping around the nozzle. You can set the sensitivity to low, medium, or high; higher sensitivity pauses on smaller problems, which costs nothing worse than an occasional false alarm on a printer you don’t know well yet.
This same camera also runs a separate, slower clog check: it samples an image every 60 to 120 seconds and looks specifically for material built up and wrapped around the toolhead. If it sees that in two consecutive checks, it pauses the print and sends a notification, though Bambu is upfront that there’s real lag here (up to about two minutes) and that this check is mainly there to protect the hardware, not to save the model already in progress.
The Air-Printing Detection Gap
Separate from the camera-based clog check, the H2S also has a mechanical way of noticing when the nozzle isn’t actually pushing out material: the servo extruder motor watches for the resistance drop that happens when it’s turning but nothing is coming out the tip. This is useful, but it’s worth knowing exactly when it does and doesn’t apply. On the H2S, this detection only works when you’re printing from an external spool (not the AMS), using PLA, PETG, PLA-CF, PETG-CF, PA-CF, or PET-CF, through a 0.4 mm nozzle, at a flow rate above roughly 9.6 mm³/s. Outside those conditions, meaning AMS-fed prints, other materials, other nozzle sizes, or slower flow rates, a clog can happen and this particular system won’t catch it. The camera-based clog check above is a partial backstop, but it has its own lag and isn’t foolproof either. Practically, this means keeping an eye on the first few layers yourself is still worthwhile no matter what material or feed setup you’re using.
One more thing worth a caution on a first print: if your bed temperature is set too far above what your filament can handle before it re-solidifies, softened material can back up into the nozzle and cause a clog of its own. This is a separate issue from anything the sensors above are checking for, so it’s worth double-checking your bed temp actually matches the filament you loaded, especially if you changed materials right before this print.
A Normal First Layer vs. One Worth Stopping For
A first layer with minor line-width variation or a little waviness over a small fraction of the surface, while the rest lays down flat and even, is normal and won’t affect the finished print. What’s worth stopping for is different: a nozzle that’s clearly scraping and dragging across the plate rather than laying lines down cleanly (too close), or lines that look sparse and separated with visibly weak adhesion to the plate (too far). The first case risks damaging the plate coating or clogging the nozzle outright. The second usually means the part won’t stay stuck down and will shift or lift later in the print, which is exactly how spaghetti failures start. If you see either pattern across a large area of the plate rather than an isolated corner, stop the print, let the bed cool, and check the leveling before trying again.
If the Print Pauses
If you get a door or top-cover open notification mid-print, close it up and the print can typically continue, though the printer will flag the interruption. If you get a first-layer defect or suspected spaghetti flag, don’t just dismiss it and walk away. Walk over, look at the plate, and decide for yourself whether what you see matches "minor cosmetic issue" or "this part is not going to finish successfully." The sensors are there to get your attention, not to make the call for you.
Related H2S guides
This is part two of a five-part Bambu Lab H2S setup series: Unboxing and Safe First Setup, Bed Leveling and Calibration, Loading, Unloading and Changing Filament, and Bambu Studio Setup. If the printer throws a fault code, see the H2S Error Code Index.