Voron Pressure Advance Guide — Perfect Corners and Seam Quality

校准 Klipper Tuning

Pressure Advance (PA) is the single most impactful software tuning parameter on any Voron printer. When set correctly, it eliminates bulging corners, sharpens seams, and improves dimensional accuracy across all print speeds. When wrong, it produces either rounded, blobby corners (PA too low) or under-extruded seams and gaps (PA too high). Getting PA right separates a good Voron print from an exceptional one. 最后更新：2025年5月。

本指南涵盖掌握 Voron 上 Pressure Advance 所需的一切：PA 在物理层面的作用、使用 Klipper 的 TUNING_TOWER 命令进行校准塔的方法、结果解读、耗材专属配置、smooth_time 调优、PA 与 input shaper 的交互，以及常见错误排查。无论你使用的是 V2.4 上的直接驱动 Revo Voron，还是 Switchwire 上的 Bowden 配置，都能在此找到精确步骤。

Pressure Advance 的作用

Pressure advance 补偿熔融耗材在压力下的物理行为。以下是未使用 PA 时的情况：

• 加速阶段： When the toolhead speeds up, the extruder must push extra filament to pressurize the melt zone before the hotend reaches full speed. Without PA, the first part of every move is underextruded — you get a gap at the start of each perimeter.
• 减速阶段： When the toolhead slows down or stops (at corners), the pressurized filament continues to ooze out. Without PA, corners bulge outward because excess filament is deposited as the pressure dissipates.
• PA同时解决这两个问题： Klipper calculates the required extruder acceleration to maintain constant nozzle pressure. It adds extra extrusion during acceleration (to fill the melt zone) and retracts slightly during deceleration (to relieve pressure). The result: consistent extrusion regardless of toolhead speed changes.

PA与Linear Advance对比： Klipper's Pressure Advance is the successor to Marlin's Linear Advance. PA is more accurate because it operates in the time domain (not the position domain) and compensates for the full acceleration profile, not just speed changes. Klipper PA is the gold standard for extrusion compensation.

为何 PA 对 Voron 打印机至关重要

Voron 打印机以高于普通打印机的速度和加速度运行，这使得 PA 尤为关键：

• 高加速度会放大误差： At 10k-20k mm/s^2 acceleration, the pressure dynamics in the nozzle are extreme. Without PA, corners on a V2.4 at 10k acceleration will bulge by 0.2-0.4mm — enough to ruin press-fit tolerances on functional parts.
• Bowden与直驱对比： Bowden setups (older Vorons or converted printers) need much higher PA values (0.4-0.8) because the long PTFE tube acts as a spring — pressure changes take longer to propagate. Direct drive setups (Stealthburner, Revo Voron, Dragon UHF) need lower values (0.02-0.08) because the extruder is right at the hotend. The tuning procedure is identical, but the target values differ by an order of magnitude.
• Voron热端特定： Different Voron hotends have different melt zone volumes. The Revo Voron (short melt zone, high thermal efficiency) needs slightly lower PA than a Dragon UHF or Mosquito. The Phaetus Dragon has a longer melt zone and may need 10-20% higher PA than a Revo.
• 速度范围： Vorons print at 60-500mm/s depending on the model and material. A properly tuned PA value should work across the full speed range. If it only works at low speeds, your smooth_time or nozzle temperature is wrong.

PA 校准塔方法

在 Klipper 中调优 PA 的标准方法使用带有 TUNING_TOWER 命令的测试打印件。步骤如下：

步骤 1：打印校准模型

你需要一个空心立方体或 PA 校准塔。最佳模型是 20x20mm 的空心立方体，无填充，2 层壁，2 层顶部/底部。或使用 Voron Designs 仓库中的专用 PA 校准塔。关键要求：一个笔直的垂直壁面，以便观察每个 PA 值下的转角质量。

步骤 2：配置调优塔

在切片软件的起始 G-code 中添加以下命令。以下示例在 30mm Z 高度上从 0 到 0.1 调优 PA，适用于直接驱动：

; PA calibration tower — direct drive range (0 to 0.1)
; Adjust PARAMETER=PRESSURE_ADVANCE and START=0, FACTOR=0.0033 for direct drive
; For Bowden: START=0, FACTOR=0.033 (range 0 to 1.0 over 30mm)
TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=0.0033
    

If you're using the TUNING_TOWER in your slicer's start g-code, you can also use the KAMP (Klipper Adaptive Mesh and Purging) scripts which automate the PA tower process:

; KAMP-style PA tuning (requires PA_Tower.cfg)
PA_TOWER START=0 FACTOR=0.0033
    

步骤 3：打印并观察

Slice the model at 100mm/s, 0.2mm layer height, with the acceleration set to at least 5,000 mm/s^2 (higher is better — 10k is ideal). Print the model and watch the corners:

• 塔底（PA过低）： The corners will bulge outward. The bulge is most visible on the outside corner where two walls meet. You'll see a distinct "fat" look at each corner — the material oozes out as the nozzle decelerates.
• 塔中（PA在范围内）： The corners become sharp and crisp. The walls are straight and meet at a clean 90-degree angle. You might still see a tiny seam line, but no bulging.
• 塔顶（PA过高）： The corners look "starved" or under-extruded. You may see gaps at the seam, thin corners, or even holes where the nozzle pulls away from the wall during deceleration. The surface quality degrades and the wall may look rough.

步骤 4：测量并设置 PA 值

打印完成后，找到转角效果最佳（锐利、无鼓包、无缺料）的 Z 高度。该高度处的 PA 值为：

PA_value = START + (best_Z_height * FACTOR)

Example: START=0, best at 15mm with FACTOR=0.0033
PA_value = 0 + (15 * 0.0033) = 0.0495

Set this in your printer.cfg:
[extruder]
pressure_advance: 0.050
    

For Bowden setups with START=0 and FACTOR=0.033, if the best point is at 18mm: PA_value = 0 + (18 * 0.033) = 0.594

Klipper 中的耗材专属 PA 配置

Different filaments need different PA values. A single PA value in printer.cfg is a compromise. Klipper supports per-filament PA via the g-code macro system or through the SET_PRESSURE_ADVANCE command in your slicer start g-code:

; In your slicer start g-code — set PA per filament material
; PLA profile
SET_PRESSURE_ADVANCE ADVANCE=0.045

; PETG profile
SET_PRESSURE_ADVANCE ADVANCE=0.055

; ABS profile (most common for Voron parts)
SET_PRESSURE_ADVANCE ADVANCE=0.050

; TPU profile
SET_PRESSURE_ADVANCE ADVANCE=0.080
    

You can also define PA in your filament start g-code within your slicer profiles. In SuperSlicer or Orca Slicer, add the SET_PRESSURE_ADVANCE command to the "Filament start G-code" field. This way, PA is automatically set when you change filaments — no manual config file editing required.

Voron直驱（Revo、Dragon、Mosquito）的推荐起始PA值：

• PLA：0.030-0.050 — PLA 粘度较低，所需 PA 较少
• ABS/ASA：0.045-0.070 — ABS 因熔融流动指数较低需要更多 PA
• PETG：0.040-0.060 — 类似 ABS 但更易拉丝
• PET-CF：0.060-0.090 — CF 耗材较硬，需要更多压力补偿
• TPU/TPE：0.070-0.120 — 柔性耗材可压缩，需要最多 PA
• PC：0.050-0.080 — 聚碳酸酯粘度高，PA 适中

Smooth_Time 参数 — PA 响应微调

The smooth_time parameter controls how Klipper smooths the PA signal. It's probably the most misunderstood PA parameter:

• 默认值： 0.040 (40 milliseconds). This is a good starting point for most Voron setups.
• 过低（0.010-0.020）： PA reacts instantly to speed changes. This can cause "ringing" in the extruder — the extruder motor makes a buzzing sound on sharp corners, and you may see artifacts in the print from the jerky extrusion signal.
• 过高（0.080+）： PA responds sluggishly. You lose the benefit — corners will bulge because the pressure compensation arrives too late.
• 如何调校： Print the same PA calibration tower but vary smooth_time instead. Set SET_PRESSURE_ADVANCE ADVANCE=<your_value> in the start g-code, then TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=SMOOTH_TIME START=0.010 FACTOR=0.005. Look for the height where the extruder sounds smooth (not buzzing) and the corners remain sharp. For most Vorons with direct drive, 0.035-0.045 is the sweet spot.

PA 与 Input Shaper — 交互机制

Pressure Advance和Input Shaper是Klipper调校的两大支柱，它们之间存在重要的相互作用：

• 先调PA，再调IS： Always tune PA before input shaper. PA changes the extrusion pattern, which can change the vibration characteristics of the print. If you tune input shaper first and then change PA, you may need to re-tune input shaper.
• PA也能减少振纹： Don't expect PA to fix ringing (ghosting) — that's input shaper's job. But a poorly tuned PA value can cause ringing-like artifacts. If you see diagonal lines on a vertical surface that look like ringing, first check your PA — it might be too high, causing the extruder to oscillate.
• 高PA+高加速度： At very high accelerations (15k-20k), a high PA value can cause the extruder to skip steps. This happens because the extruder must accelerate so quickly that it can't keep up with the pressure demand. If you see extruder skipping on corners at high speed, reduce acceleration or reduce PA slightly.
• PA测量与校准对比： Klipper's MEASURE_PRESSURE_ADVANCE command (available in Klipper 0.12+) uses the load cell or accelerometer to auto-tune PA. This is the most accurate method and is recommended if you have a Klicky or Voron Tap probe with the appropriate setup. The measurement method finds the exact PA value in minutes rather than the 20-30 minutes of trial-and-error printing.

常见 PA 错误与故障排除

• PA过高→接缝处挤出不足： The most common mistake. High PA retracts too much on deceleration, starving the seam. Solution: reduce PA by 0.010-0.020 and re-test. If the seam is still under-extruded at PA=0, your smooth_time is too low — increase it to 0.050.
• PA过低→角落鼓包： The second most common issue. Increase PA in 0.005 increments (direct drive) or 0.05 increments (Bowden) until the corners are sharp. If you need PA above 0.12 for direct drive, check your hotend — the nozzle or heat break might be partially clogged.
• PA在低速下有效但高速下无效： This usually means your smooth_time is too high. At high speeds, the PA signal needs to react faster. Lower smooth_time from 0.040 to 0.025 and re-tune PA.
• PA works at high speed but not low speed: This means PA is too high or smooth_time is too low. The extruder is over-correcting on low-speed moves. Try increasing smooth_time to 0.055.
• Different PA needed for outer vs inner perimeters: This is normal. Outer perimeters run at the set speed; inner perimeters often run faster. You can set different PA values for outer perimeters in Klipper 0.11+ using SET_PRESSURE_ADVANCE EXTRUDER=extruder PRESSURE_ADVANCE_LOOKAHEAD_TIME=0.010. Most users find that the standard PA value works well for both when tuned correctly.
• PA causes extruder clicking on retractions: Your PA value is too high for your retraction speed. Either reduce PA or reduce retraction speed to 30-40mm/s. A common Voron retraction setting (0.5-1.0mm at 35mm/s) is compatible with PA values up to 0.10.