Calibration tower calculator: pressure advance, max flow and temperature towers
What it calculates
Towers that change every layer use value = start + measured height × step per mm. Klipper's pressure advance example: 0 + 12.90 × 0.020 = 0.258 [1]. OrcaSlicer's PA tower rises one step per millimetre [2], and its max volumetric speed test uses start + height × step (5 + 19 × 0.5 = 14.5 mm³/s) [3]. Block towers change the value once per block instead.
Two kinds of tower
Calibration towers turn one setting up (or down) as the print grows, so a single print shows many values. Reading one means finding the height where the print looks best and converting that height back into the setting. There are two patterns:
| Tower | Value changes | Formula |
|---|---|---|
Klipper TUNING_TOWER (pressure advance) |
every layer | start + height × factor [1] |
| OrcaSlicer pressure advance tower | every layer, one step per mm | start + step × height [2] |
| OrcaSlicer max volumetric speed test | continuously with height | start + height × step [3] |
| Temperature tower | once per block | start + block number × step |
Choose “Changes every layer” for the first three and “Changes per block” for temperature towers or any other block-based test.
Continuous towers
Klipper pressure advance
Klipper’s guide prints a hollow square tower and changes pressure_advance on every layer with TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=.005 for direct-drive extruders, or FACTOR=.020 for long Bowden setups [1]. Before the print it lowers cornering speed and acceleration with SET_VELOCITY_LIMIT SQUARE_CORNER_VELOCITY=1 ACCEL=500 to make pressure effects easier to see [1].
Measure the height with the best corners using calipers; the value is start + height × factor. Klipper’s own example is 0 + 12.90 × 0.020 = 0.258 [1]. The presets in the calculator fill in both documented FACTOR values.
OrcaSlicer pressure advance tower
OrcaSlicer’s tower method raises pressure advance from the start value at the bottom to the end value at the top, one step per millimetre, and cuts the tower to the range you request. Its worked example selects 8 mm with a 0.002 step: 0 + 0.002 × 8 = 0.016 [2]. Enter the start and step from the test dialog.
OrcaSlicer max volumetric speed
The flow test prints a tower whose flow rises with height. The recommended defaults are a start of 5 mm³/s, an end of 20 mm³/s and a step of 0.5 [3]. Measure up to just before the defects begin; OrcaSlicer’s example reads 19 mm, giving 5 + 19 × 0.5 = 14.5 mm³/s [3]. Then turn that into a print speed with the volumetric speed calculator, after backing it off as described below.
Block towers
A temperature tower prints a stack of blocks, each at a different nozzle temperature [4]. Reading it needs the block height, the temperature of the first block, the step between blocks, and the height of any base below the first block. Measure from the bed to the middle of the block you like, or count blocks from the bottom. Check the block height and order in the slicer’s preview, because tower models differ and some start hot at the bottom and step down.
OrcaSlicer’s advice when several blocks look good is to take the middle of that range, or the higher end if you plan to print fast [4].
Reading the print, not just the number
- Prefer lower when unsure. Klipper’s guide says to prefer a lower height when in doubt for pressure advance [1].
- Back off the flow limit. OrcaSlicer calls its max flow test a best case that ignores retraction and other factors, and suggests 10–20% less [3].
- Expect normal ranges. Klipper puts typical pressure advance between 0.050 and 1.000 [1]. A result far outside your extruder type’s usual range suggests a misread tower or a setup problem.
The full procedures are in the guides for pressure advance, temperature towers and max volumetric speed.
Questions
Should I pick the best-looking height or a slightly lower one?
Klipper's pressure advance guide says to prefer a lower height when in doubt [1]. For max volumetric speed, OrcaSlicer suggests reducing the measured value by 10–20% or more because the test is a best case [3].
What pressure advance values are normal?
Klipper's documentation gives typical values between 0.050 and 1.000, with the high end usually only on Bowden extruders, and says that if nothing improves up to 1.000, pressure advance is unlikely to help [1].
Sources
- Pressure advance. Klipper documentation. Firmware documentation. TUNING_TOWER parameters for direct drive (FACTOR .005) and Bowden (FACTOR .020); value = start + height × factor; typical range. Accessed October 12, 2026.
- Pressure Advance calibration. OrcaSlicer Wiki. Slicer documentation. Tower method: one step per millimetre, PressureAdvanceStart + step × height. Accessed October 12, 2026.
- Max Volumetric Speed (FlowRate) Calibration. OrcaSlicer Wiki. Slicer documentation. Default 5–20 mm³/s, step 0.5; start + height × step; reduce 10–20%. Accessed October 12, 2026.
- Temp Calibration. OrcaSlicer Wiki. Slicer documentation. Temperature tower: blocks at different temperatures; choose the middle of a good range. Accessed October 12, 2026.