Why some plastics warp and others do not
Every plastic shrinks as it cools, but not equally. When the lower layers cool and shrink while the upper layers are still hot, the part pulls its own corners off the plate or cracks between layers. Bambu Lab’s filament guide puts ABS, ASA, PC, PA (nylon) and their fibre-filled versions in a group that requires higher heatbed and chamber temperatures to suppress warping and layer separation and to ensure interlayer strength, and recommends an enclosed printer for them [1].
PLA, PETG and TPU sit in the other group: not prone to warping, with no mandatory temperature requirements, printable on open or enclosed printers [1]. PETG has a caveat: Bambu Lab recommends an enclosure to stop low room temperatures weakening layer bonds [1].
This page is about the chamber. If you are choosing between ABS and ASA, see our material comparison.
Passive enclosure versus heated chamber
A passive enclosure is a box with a door. It warms up only because the heated bed and electronics release heat into it. Bambu Lab says plainly that the P1S chamber is not actively heated: its temperature rises with the bed setting and cannot be precisely controlled [2]. The P2S is the same, with no active chamber heating, but regulates temperature with an automatic flap that switches between internal and external air circulation [3]; Bambu Lab markets it as 50 °C chamber ready [3].
An actively heated chamber has its own heater and a target temperature. Bambu Lab lists 65 °C active chamber heating on the H2D [4]. Creality lists an active chamber heater on the K2 Plus and a chamber temperature up to 60 °C [5].
The difference matters most for large parts. A passive chamber may be warm enough for a small ABS bracket but not for a long, thick part whose ends cool while the nozzle is far away.
Which materials need which
The material guidance below is Bambu Lab’s, because it is the only maker we checked that publishes a printer requirement per material group. Practical notes combine it with the printer specifications that follow.
| Material | Vendor printer guidance | Practical setup |
|---|---|---|
| PLA, TPU | Open or enclosed; not prone to warping [1] | Open printer, or enclosure with door or lid open when bed is above 45 °C [1] |
| PETG | Open or enclosed; enclosure recommended in cold rooms [1] | Enclosure, door open when bed is above 60 °C [1] |
| ABS, ASA | Enclosed printer recommended; needs higher bed and chamber temperatures [1] | Passive enclosure for small parts; heated chamber helps large ones |
| PC, PA (nylon) | Enclosed printer recommended [1] | Heated chamber preferred for anything large |
| CF and GF filled versions of the above | Same as the base material [1] | Plus a hardened nozzle [1] |
Printers and their published chamber specs
Only what the vendor pages we checked state is listed. Creality’s K1C store page lists ABS, ASA and PC among supported filaments [8] but does not publish a chamber temperature.
| Printer | Chamber type | Published chamber figure |
|---|---|---|
| Bambu Lab A1 | Open frame; Bambu does not recommend enclosing it [6] | None; ABS, ASA, PC and PA limited to small, low-infill parts [7] |
| Bambu Lab P1S | Passive enclosure [2] | None; rises with bed temperature [2] |
| Bambu Lab P2S | Passive with automatic airflow flap [3] | Marketed as 50 °C chamber ready [3] |
| Bambu Lab H2D | Actively heated [4] | 65 °C [4] |
| Creality K1C | Not described on the page checked; ABS, ASA and PC listed as supported [8] | Not published on page checked [8] |
| Creality K2 Plus | Actively heated [5] | Up to 60 °C [5]; 120 °C bed and 350 °C nozzle [10] |
The PLA caveat: open the door
An enclosure can hurt low-temperature materials. Bambu Lab explains that filament with a softening temperature below 60 °C, such as PLA, PVA and TPU, can soften inside the extruder and cause abnormal extrusion or clogs if the chamber gets too warm [1]. Its advice is to open the front door and/or remove the top glass cover when the bed is above 45 °C for those materials, and above 60 °C for PETG, which softens between 60 and 80 °C [1].
Bambu Lab adds that this matters more in a warm room and less in a cold one [1]. If your enclosed printer clogs on PLA in summer but not winter, chamber heat is the first suspect.
What heat costs in power
Holding a chamber warm costs electricity. Bambu Lab’s measurements show the passive P1S averaging 105 W on PLA and 140 W on ABS [9]. The H2 series, which can heat its chamber, averaged about 197 W on PLA and 395 W on PC for the H2D [9]. The K2 Plus uses an 800 W AC heatbed according to Creality [5]. Our electricity guide turns these figures into yearly costs.
Who needs which
Match the chamber to the hottest material you expect to print regularly, not the one you might try once.
- PLA and PETG only: an open printer is fine; an enclosure helps with noise, dust and PETG in cold rooms.
- Occasional small ABS or ASA parts: a passive enclosure such as the P1S class is enough for most.
- Large ABS, ASA, PC or nylon parts, or regular engineering work: look for a published, actively heated chamber figure.
- Open-frame owners: Bambu Lab does not recommend enclosing the A1 [6], so do not plan to add a box later.
Questions before you decide
Does the Bambu Lab P1S have a heated chamber?
No. Bambu Lab says the P1S chamber is not actively heated; it warms with the bed and cannot be precisely controlled [2].
Which printers publish a heated chamber temperature?
Of the pages we checked, Bambu Lab lists 65 °C active chamber heating on the H2D [4] and Creality lists up to 60 °C on the K2 Plus [5]. The P2S is marketed as 50 °C chamber ready but has no active heater [3].
Should I close the door when printing PLA?
Not when the bed is hot. Bambu Lab recommends opening the door or removing the top cover for PLA when the bed is above 45 °C, so the filament does not soften in the extruder [1].
Can I print ABS on an open printer?
Only small parts. Bambu Lab says the open-frame A1 risks reduced layer strength and warping with large or dense ABS, ASA, PC or PA parts, but can print small low-infill ones [7].
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- Bambu Lab Wiki: Filament guide - printer, nozzle, build plate and parameters Accessed 30 Oct 2026
- Bambu Lab Wiki: P1 series FAQ Accessed 30 Oct 2026
- Bambu Lab US store: P2S product page, specifications and FAQ Accessed 30 Oct 2026
- Bambu Lab US store: H2D product page and specifications Accessed 30 Oct 2026
- Creality store blog: K2 Plus and CFS FAQs Accessed 30 Oct 2026
- Bambu Lab Wiki: A1 FAQ Accessed 30 Oct 2026
- Bambu Lab US store: A1 product page and specifications Accessed 30 Oct 2026
- Creality store: K1C 3D printer listing Accessed 30 Oct 2026
- Bambu Lab Wiki: Printer and AMS power parameters Accessed 30 Oct 2026
- Creality: K2 Plus Combo support page and parameters Accessed 30 Oct 2026
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