How to Keep Local Rig Controls Editable Inside a Full-Turn Smart Bone Action

A Smart Bone can drive expressions, face rotations, and entire body turns through an associated action. The action therefore needs careful boundaries: every additional element you key inside it becomes part of what the turn controls. Moho’s official Features page describes this relationship between a Smart Bone, its action, and the animated elements.

A relevant troubleshooting discussion reports pupils and brows snapping back after manual edits. Animator D. R. Greenlaw recommends checking for Smart Bone keys on those elements and separating manual animation onto another item, such as a child bone or group layer. That is practical troubleshooting guidance rather than a universal description of every channel’s blending behavior. See Making a smart action - everything dissapears..

Before rebuilding anything, identify the exact item and channel involved. A pupil’s layer translation, its controlling bone’s translation, and its vector points are different animation targets. A clean-looking bone timeline does not establish that the artwork has no action keys.

Use a small ownership plan before editing the rig. The following is a proposed setup derived from Moho’s documented hierarchy and the troubleshooting guidance above; the names are illustrative.

Element	Responsibility	Where to animate it
Turn_Dial	Select the turnaround position	Its Smart Bone Action and Mainline dial animation
Pupil_Carrier	Place the pupil assembly for each view	Turn action
Pupil_Local	Add the animator’s pupil adjustment	Mainline
Pupil artwork	Follow the local control	Binding established during setup

The hierarchy is character parent → Pupil_Carrier → Pupil_Local. Moho documents that moving a parent moves its children, while moving a child leaves the parent unchanged. This supplies the mechanical basis for carrying a local control through a turn while preserving a separate adjustment beneath it. See the official Bone Layers documentation.

Use the ownership plan to answer a specific question for each key: does this change describe where the feature belongs in the turnaround, or what the animator wants it to do in the shot? Put the first operation on the carrier and the second on the local control. For a feature that also changes shape, record which points or deformation controls own that shape change.

Start with a saved copy of the character file. For the first trial, choose one feature with simple artwork and an obvious pivot. A rigid pupil element is easier to diagnose than a feature already affected by several deformations.

1. Return to frame 0 and select the appropriate bone layer.
2. Create a carrier bone at the feature’s intended attachment position.
3. Create the local control as the carrier’s child, or use Reparent Bone to assign that relationship.
4. Attach the artwork to the local control using the binding method appropriate to the feature.
5. Move to an animation frame and test the carrier and local control separately.

Moho’s official Bone Tools documentation explains creating children, changing parents, and binding an entire layer to one bone. It also distinguishes frame 0 setup from animation on later frames. Its interface descriptions are from an older manual, so use the corresponding tools in your installed version.

For an isolated rigid artwork layer, binding the whole layer to the local bone gives the trial a clear relationship. For a deforming vector feature, retain an appropriate point or flexible binding arrangement and check which bones influence it. A carrier that also deforms unrelated artwork will make diagnosis harder.

At an animation frame, move the carrier with the child neutral. Then restore the carrier and move only the child. Check that both operations affect the intended artwork and that neither introduces an unwanted change elsewhere. Complete this small test before adding turnaround keys.

Repair one feature at a time. Record its placement at the front, both profiles, rear, and useful intermediate views. These reference poses give you something concrete to compare after changing the hierarchy.

Inside the turn action, reconstruct the feature’s view-dependent placement with the carrier. Once a view matches, inspect the local control and artwork for redundant keys that perform the same placement. Remove only the confirmed redundant keys in the working copy. Keep intentional shape corrections until you have checked their purpose.

Avoid blindly copying transform values from the old local bone to its new parent. Reparenting changes the coordinate relationship. A separate Smart bone dial issue discussion specifically identifies changed parent rotation as a possible cause of incorrect child rotation values.

After each feature, return to the Mainline and test an actual local pose while the turn is active. Do this before migrating the next feature. If the local control works but the artwork drifts, investigate binding or duplicate placement. If the local pose disappears, inspect the affected channels across the active actions.

Distinguish a character’s complete turnaround from Moho’s dedicated 360-degree Smart Bone feature. Lost Marble introduced that feature in Moho 14.4 and states that Moho recognizes a 360-degree Smart Bone when its rotation is exactly 360 degrees. The update also adds Shift-assisted snapping to multiples of 360 degrees relative to the frame 0 angle. See the official Moho 14.4 SIDE QUEST announcement.

For that feature, check the numerical rotation rather than judging the dial by appearance. A bone pointing in its original direction does not, by itself, document the intended rotation range. If your existing turnaround uses another action arrangement, preserve that arrangement while fixing local control ownership.

For predictable dial mapping, consider Linear interpolation inside the action and apply the shot’s easing on the Mainline. How to Create Rig Controllers for a Character in Moho records this recommendation from animator Danny Sugar. Treat it as a starting condition; intentionally nonlinear deformation may require different interpolation.

Inspect the turnaround boundary with a local pose applied. Compare carrier placement, artwork shape, and visibility immediately before and after the return to the starting view. Matching neutral endpoints alone is an incomplete test of an editable rig.

Use a repeatable pose matrix. The suggested angles below describe character views; they need not equal your dial’s numeric angles. The checks are a diagnostic procedure, not measured results.

Turn position	Neutral local control	Local pose A	Local pose B
Front	Check attachment	Apply a small adjustment	Apply the opposite adjustment
First profile	Check placement	Check direction and range	Check artwork alignment
Rear	Check intended visibility	Check the stored pose	Check return behavior
Opposite profile	Check placement	Check direction and range	Check artwork alignment
Return to front	Compare with starting view	Check boundary continuity	Check boundary continuity

Run two passes. First, hold the turn still and animate the local control across several frames. Second, hold a local pose and animate the turn through its range. The first tests local editability; the second tests whether the turn carries that pose coherently.

Keep the trial adjustments small enough that you can distinguish a control conflict from an unfinished drawing. If an extreme pose looks wrong only in profile, the feature may need view-specific deformation work. Separating transforms preserves a place for editing; it does not author every required silhouette.

If the action preview works but the Mainline does not, check the driver’s keyed angles, unintended keys, and any nested bone layers. The original Smart bone dial issue thread documents these as separate diagnostic possibilities. It also describes using a uniquely named child action for a nested Smart Bone setup.

Distinguish a child bone within one skeleton from a child bone layer. Introducing another bone layer changes the control arrangement. Anime Studio Tutor’s Control Bones From Parent Layer documents an explicit script-based bridge between layers, labeled for Moho Pro 12. That historical implementation is useful evidence that cross-layer control needs deliberate setup; it is not a prerequisite for the carrier-and-child workflow.

Before adding more structure, return to the smallest failing example: one turn driver, one carrier, one local control, and one artwork element. Confirm the hierarchy, binding, and action keys there. Expand only after the local pose remains editable while the turn changes.

The finished rig should let you stop at any intended view, pose the local feature, and continue turning without losing that adjustment. Establish that behavior on one feature first, then apply the same explicit division of responsibilities to the remaining controls.

• Features — Lost Marble
• Bone Layers — Moho Manual
• Bone Tools — Moho Manual
• Making a smart action - everything dissapears. — Moho Animation Forum
• Smart bone dial issue — Moho Animation Forum
• FREE UPDATE: Export to video game engines and 3D software with Moho 14.4 SIDE QUEST — Lost Marble
• How to Create Rig Controllers for a Character in Moho — Lesterbanks
• Control Bones From Parent Layer — Anime Studio Tutor