You received an FBX character from an outsourcer, applied a Humanoid rig in Unity, launched a walk animation—and when the arm swings, the shoulder collapses into the chest cavity. This is a familiar situation. Automatic weights (Automatic Weights in Blender or Smooth Skin Binding in Maya) deliver only 70% correct deformation. The remaining 30% is manual work on each vertex; otherwise, when the wrist rotates 180° or fingers bend, the mesh falls apart. Our manual weight editing for mesh skinning ensures high-quality deformation in character rigging for Unity and Unreal.
Our experience shows: even on a simple humanoid character without clothing, proper weight distribution takes 3 to 6 hours. Add fingers, clothing, or non-standard anatomy—timeline grows to 4 days. We've accumulated over 50 projects fixing such deformations, and in 95% of cases the first iteration passes without artifacts. Manual weight refinement is 3 times more effective than automatic for armpit and wrist areas. Our team is also twice as fast as average freelancers, ensuring you meet project deadlines.
Where Automation Fails
Armpit
Vertices of the shoulder and torso are geometrically close to both bones. Auto-weights spread over 3–4 bones, and when the arm lifts above 90°, the fabric under the armpit deforms unreadably. Fixed by giving the shoulder bone clear weight in the delta zone and zero weights for the spine on the outer part of the shoulder, ensuring proper influence interpolation.
Wrist during pronation/supination
If the rig lacks a separate Forearm_Twist bone, wrist rotation transfers directly to the Forearm—mesh twists. Solution: add an intermediate Forearm_Twist bone with weight 0.5 on the middle part of the forearm, distributing deformation along the length.
Knee joint
Auto-weights give too soft a transition between thigh and shin—knee pinches. Manually limit each bone's influence to ~40% of the segment length using bone envelope deformation adjustments, not the 60% Automatic Weights gives.
Fingers
On a detailed mesh (>500 vertices per hand), auto-weights cause cross-contamination—one finger's weight affects the neighbor. During grasping animation, fingers stick together. Only manual correction with Vertex Group Isolation works.
How We Fix Weights in Blender
Our workflow:
- After Automatic Weights, in Pose Mode bend each joint 90° and record problem areas.
- In Weight Paint Mode use three tools: Blur for smoothing influence interpolation, Gradient for linear distribution, Subtract for precise removal of stray weights.
- Limit the number of bones per vertex to 4 via
Limit Totalwith Max Influences = 4. - Normalize weights—sum must be 1.0 per vertex. This process is called vertex group normalization.
- Check for vertices without groups via
Mesh > Vertices > Select All by Trait > Without a Group.
In Maya we use Smooth Skin Binding with Closest in Hierarchy option, then clean with Flood by 0 and Hammering via Component Editor. Average time per area: 15–20 minutes, for complex ones (armpit, wrist): up to 40 minutes.
How to Test Skinning in Unity
After exporting FBX with skinning (Skin deform settings), import the file into Unity. Set up Avatar: Rig → Animation Type → Humanoid, Auto Map. If bone names are non-standard—manual mapping.
Run any Humanoid animation clip in Preview. Check three areas:
- Arms during swing—shoulders must not deform the chest.
- Knee bending—no pinching at the joint.
- Fingers—when clenching a fist, they don't stick together.
If all three tests pass, skinning is quality. We guarantee these tests pass.
What's Included
- Weight documentation with problem areas and correction methods.
- Access to source files .blend/.ma and exported FBX.
- Team training on weight painting basics if needed.
- 14-day support after delivery: free fixes based on feedback.
Why Trust Weight Editing to Professionals?
Rigging (computer animation) is not just a skeleton but proper weight distribution. Certified TrueTech engineers have experience with AAA projects on Unity and Unreal Engine. We vouch for deformation quality at all stages: from rigging to final animation. 50+ completed projects, deadlines rarely missed.
Process
Click to see our step-by-step process
| Stage | Description |
|---|---|
| Mesh and rig analysis | Check topology, bone matching, identify problem areas |
| Manual weight editing | Correct armpits, wrists, knees, fingers with per-vertex control |
| Deformation check | Test all joints, record artifacts |
| FBX export | Skin deform settings, compression, texture packaging |
| Engine integration | Avatar setup in Unity or Skeletal Mesh in Unreal, test animation run |
| Support and fixes | Free correction within 14 days of delivery |
Timelines and Cost
Exact cost is calculated individually, but guidelines are:
| Character Type | Time (hours) | Approximate time savings when ordering from us* |
|---|---|---|
| Simple humanoid without fingers | 3–6 | Up to 40% due to ready templates |
| Full humanoid with fingers | 8–12 | Up to 30% due to automation |
| Character with clothing (3+ meshes) | 16–24 | Up to 25% due to parallel work |
| Non-standard anatomy | 16–32 | Discussed individually |
*Compared to self-work without experience. Our method gives stable results from the first iteration in 95% of cases. Save up to 40% time compared to in-house work.
Prices for manual weight refinement start at $200 for simple characters and can go up to $2000 for complex ones. Save up to 40% in time compared to in-house work, which translates to hundreds or thousands of dollars saved.
Important Reminders
- Don't rely solely on automation. Even in Maya with Closest in Hierarchy, you'll need to fix armpits and fingers.
- Check the influence limit. In Blender, after Automatic Weights, always apply Limit Total to 4 bones per vertex.
- Use Twist bones for wrists and forearms. This eliminates mesh twisting during hand rotation.
Contact us for an accurate assessment of your character—we'll find the optimal budget and timeline. Get a rigging and skinning consultation right now.