Bambu Lab P1S · FDM Troubleshooting

P1S Supports Welded to Your PLA+ Print? Fix the 0.2 mm Gap — Then Open the Door

"My supports get stuck on my print and it comes off rough." A maker in a printing Discord asked this last night — PLA+, normal supports, snug style. On a Bambu Lab P1S there are exactly two things going on: the invisible air gap in your slicer, and the fact that you're printing PLA+ inside a warm box. Here's the complete fix, setting by setting, in Bambu Studio.

By Dreaming3D · Carmel Valley, San Diego · July 14, 2026 · 9 min read

Every FDM support system works on one trick: the slicer leaves a tiny air gap between the top of the support and the bottom of your part. Your part's first overhanging layer droops microscopically across that gap, bonds to itself just enough to print, and — because it never properly fused to the support — pops off cleanly afterward. Kill that gap, or let heat and extra plastic squeeze into it, and the support becomes part of the model. Then removal isn't removal; it's surgery, and PLA+ makes the surgery bloodier because it's formulated to be tough. It doesn't snap off brittle-clean like standard PLA — it hinges, stretches, and tears chunks out of the underside. That's the "comes off rough."

The P1S adds one amplifier of its own, so let's start there.

Step 0: You're Printing PLA+ Inside a Warm Box

The P1S is fully enclosed with a passive chamber — no heater, but no ventilation to speak of either, beyond the exhaust fan. That enclosure is exactly what you want for ABS and ASA. For PLA and PLA+ it works against you: over a long print, especially in a warm garage, the chamber soaks well above room temperature. Warm overhangs don't freeze crisp — they droop into the support interface and bond to it, no matter what your slicer settings say. Bambu's own guidance and long-standing community consensus for PLA in the P1 series is simple: open the front door, and prop or remove the glass top. It costs you nothing on PLA quality and it attacks the weld at the source. (Chamber heat soak is also a driver of heat-creep clogs — if you've been seeing the extrusion motor overloaded error on hot days, same fix.)

Here in San Diego that matters double in July: a garage P1S with the lid on is running warm all afternoon, and the marine-layer humidity is quietly soaking your spool at the same time. More on that in a minute.

The Six Bambu Studio Settings, In the Order They Matter

1. Top Z distance — probably your whole problem

This is the air gap in Fig. 01 — the entire mechanism of clean removal. Under Support in Bambu Studio (and OrcaSlicer), set it to 0.2 mm at a 0.2 mm layer height — one full layer of air. Bambu's stock PLA profiles ship around that value, but custom profiles, imported profiles, and well-meaning tweaks zero it out constantly. A value at or near 0 welds same-material supports on, guaranteed — 0 is reserved for dissimilar-material interfaces (see the AMS section below). If supports still grip after everything else here, step to 0.25 mm; beyond that, the underside starts sagging because your part is bridging further across thin air. Match Bottom Z distance to the same number.

2. Support/object xy distance — stop scarring the side walls

Snug style hugs the model's outline — great for material use, but if the lateral clearance is tight, support walls fuse to part walls and tear the sides, not just the underside. Start around 0.35 mm; if vertical faces next to supports are scarred, raise it to 0.5–0.8 mm.

3. Top interface layers + Top interface spacing — a roof the part can bridge

The interface is a denser roof printed on top of the sparse support body, so your part bridges one tidy mat instead of gripping dozens of individual zigzag lines. Counterintuitively, a proper interface makes removal easier and smoother. Run 2–3 top interface layers. Spacing around 0.2 mm gives the smoothest underside; opening it toward 0.5 mm releases easier at the cost of texture. If your underside currently looks like torn corduroy, it's usually missing interface layers entirely.

4. Temperature + the P1S's fans — the PLA+ tax

PLA+ formulas (eSUN, SUNLU, and friends) are modified for toughness and typically want hotter nozzles — many brands recommend roughly 205–230°C versus about 190–210°C for standard PLA; check your spool. Hotter plastic bonds harder to everything under it, including the support roof. Print toward the low end of your spool's range, and put the P1S's cooling to work: part fan at 100% on overhangs, and confirm the big side-mounted auxiliary fan isn't zeroed in your filament profile — it makes a real difference on overhang crispness. Which PLA+ balances toughness against printability best is covered in the PLA+ section of our 2026 filament guide.

5. Flow calibration — the P1S can't do this one for you

A perfect 0.2 mm gap does nothing if over-extrusion fills it. Here's a genuine P1S gotcha: unlike the X1 Carbon, the P1S has no lidar, so there's no automatic flow calibration — if you've never run the manual Flow rate calibration in Bambu Studio or OrcaSlicer for this specific spool, do it now. While you're at it, dry the filament: PLA+ that's been sitting open in coastal San Diego humidity oozes and strings, and stringy overhangs glue themselves to support tops. Blobby, pitted surfaces on the same print are the tell.

6. Type: tree(auto) — sometimes the answer is fewer contact points

Normal + snug is the right call for boxy geometry with big flat ceilings. For organic shapes, figures, and angled undersides, switching Type to tree — organic style in recent Bambu Studio and OrcaSlicer builds — means dramatically fewer contact points, and supports that often pull off in one satisfying piece. Slice a small section of your model both ways; the preview costs ten minutes and settles the argument.

The AMS Upgrade: Make the Gap Obsolete

If your P1S has an AMS, you have an endgame option regular-PLA folks don't: assign a dedicated support interface filament under the Filament settings (Support/raft interface). Bambu's Support for PLA is built for this, and the budget version of the trick is plain PETG under PLA+ — the two print at similar temperatures but bond so poorly to each other that the weak bond is the release mechanism. With a dissimilar interface you set top Z distance to 0, the part prints directly on the interface, and the underside comes out nearly as glassy as a top surface. Two honest caveats: every interface swap costs purge waste on a single-nozzle machine (turn on flush-to-infill options to reclaim some), and your AMS needs to be feeding reliably — if it isn't, start with our AMS troubleshooting guide. The full version of the dissimilar-interface idea, including modeling your own supports with it, is in our CAD-designed supports post.

The Roughness That's Left — Expectations and Cleanup

Honest expectations: even fully dialed, a supported underside never matches a top surface — that first layer bridged over air, and some texture is physics, not failure. Manage where it lands: rotate the part so supported faces end up non-cosmetic, chamfer overhangs under 45° out of existence at the design stage, and paint supports only where needed instead of carpeting every overhang. Remove supports only after the print cools completely — warm PLA+ smears and stretches; cool PLA+ separates cleaner — working with flush cutters along the seam rather than ripping upward. The nubs and witness marks that remain sand out fast with a proper grit progression; our sanding and post-processing guide has the exact sequence. Running a resin machine too? Support logic over there is a different universe — tips, angles, and timing are in our resin support settings guide.

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