TMC Autotune

Quieter, Cooler Steppers (TMC Autotune)

NebulaScreen has a TMC Autotune screen (Tune → Calibration → 8 TMC Autotune) that tunes your stepper drivers from the motor type — quieter motion, cooler drivers, and a touch smoother surface, applied automatically on every boot. You pick the motor and a goal from two dropdowns and tap Save. No tuning math, no datasheets.

TMC status readings.

What NebulaOS provides

• The autotune add-on (autotune_tmc.py, motor_constants.py, motor_database.cfg) from andrewmcgr/klipper_tmc_autotune, shipped in NebulaOS-klipper-extensions.
• [nebulaos_tmc_autotune] in the NebulaOS Klipper config. It adds the command NEBULAOS_TMC_AUTOTUNE, which the screen uses to add or remove [autotune_tmc <stepper>] sections before SAVE_CONFIG. Autotune itself only runs once such a section exists.

The row is greyed out only when Klipper has no motor_database.cfg; on NebulaOS it is there.

A couple of things this is not:

• It is not related to TMC Metrics (the live driver dashboard) — separate button, separate feature.
• It does not need a print running, and it is locked while one runs.

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Will this actually help me? (Honest answer for the KE)

Yes, but moderately. The Ender-3 V3 KE uses TMC2208 drivers on X, Y, and Z. The 2208 supports the chopper-timing and stealthChop/PWM tuning that autotune computes from the motor specs — so you will get quieter, cooler, slightly smoother motors. That part is real.

What the 2208 doesn't have is CoolStep and StallGuard (those are 2209-and-up features). So:

• You won't see a "Sensorless Threshold" field on the KE. The panel only shows it for drivers that support StallGuard (2209/2130/2240/2660/5160); on the 2208 it's hidden. So you've nothing to set there.
• Don't expect a transformative change. Think "noticeably calmer and cooler," not "a different printer."

If your motors are already quiet and you have no thermal concerns, this is a nice-to-have, not a must-do.

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Before you start

• ⏱️ Time: a few minutes, plus a Klipper restart.
• ↩️ Safe to try: nothing changes until you tap Save, and it's reversible (see Undoing it).

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Pick your motors and tune

No current screenshot of this screen yet - the capture tour does not reach it. Tracked in the screenshot inventory.

For each axis, choose the Motor from the dropdown, then a Tuning Goal, then tap Save/Restart.

Recommended on the KE (these are the stock motors):

Stepper	Motor	Tuning Goal
stepper_x	creality-42-34	performance
stepper_y	creality-42-34	performance
stepper_z	creality-42-40	silent

The Tuning Goal dropdown has four choices:

• auto — picks for you based on the motor: performance for X/Y, silent for Z. On the KE this lands on exactly the recommended table above, so auto is a perfectly good "just do the right thing" choice.
• performance — spreadCycle at all speeds (crisp, accurate motion, a bit more audible). Good for the moving X/Y.
• silent — stealthChop at all speeds (quietest). Ideal for the Z lead-screw, which doesn't need the precision.
• autoswitch — experimental. Runs stealthChop at low speed and switches to spreadCycle once the motor moves fast enough. The idea is "quiet when slow, strong when fast." It's flagged experimental in the add-on and isn't needed on the KE — stick with auto/performance/silent unless you're deliberately experimenting.

You'll see just the two dropdowns per axis — there's no "Sensorless Threshold" field on the KE, because the 2208 drivers don't have StallGuard (the panel hides it).

Steppers without a saved choice are pre-selected with these stock motors; nothing is written until you save.

Tap Save/Restart. The screen sends NEBULAOS_TMC_AUTOTUNE STEPPER=… MOTOR=… GOAL=… for each stepper, then SAVE_CONFIG: Klipper writes the [autotune_tmc …] sections into its auto-save block, restarts, and applies the tuned driver registers. From then on they are applied on every boot.

The motor names come from the bundled motor database. If you've swapped to non-stock motors, pick the closest match in the dropdown (or look your motor up in motor_database.cfg).

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Undoing it

To turn a single axis back to stock, set its Motor to "Not Configured" and tap Save/Restart — the screen removes that [autotune_tmc] section (NEBULAOS_TMC_AUTOTUNE STEPPER=… REMOVE=1).

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Troubleshooting

• Row greyed out — Klipper reports no klippy/extras/motor_database.cfg. Check the Klipper log for an error mentioning autotune_tmc or motor_constants.
• Save fails with "Unknown command NEBULAOS_TMC_AUTOTUNE" — the [nebulaos_tmc_autotune] section is missing from the Klipper config (it is in the NebulaOS platform.cfg).
• Where's the Sensorless Threshold field? — it isn't shown on the KE. The screen only displays it for drivers with StallGuard (2130/2209/2240/2660/5160); the KE's TMC2208 drivers don't have it.