Round sharp edges, hollow out shells, cut patterns, and mirror features to polish your parts.
Modifiers transform rough geometry into production-ready parts. This module covers edge treatments, shell, draft, patterns, mirrors, and Booleans.
The two fundamental edge treatments — each serves a different mechanical purpose.
Replaces a sharp edge with a smooth, tangent arc of a specified radius, distributing stress evenly.
Typical radii: 0.5–1.0 mm cosmetic, 1.5–3.0 mm structural, 0.2–0.5 mm CNC minimum.
Removes material at an angle (commonly 45°) along an edge, creating a flat bevel.
Typical sizes: 0.5 mm general edge break, 1.0–2.0 mm bolt-hole lead-ins, 0.3 mm cosmetic.
Select edges and specify a radius. Start with structural internal corners, then add cosmetic external fillets. You can select multiple edges in one operation.
Specify a single distance (equal chamfer) or two distances (asymmetric). 1.0 mm x 45° is the most common edge break. Use asymmetric for larger lead-ins on one face.
Select face(s) to remove and specify wall thickness. Always shell before filleting internal corners to avoid geometry failures.
Select vertical faces and specify a draft angle (typically 1–3°). Faces tilt outward for mold release. Slight draft also improves 3D-print surface quality.
Use pattern tools to repeat features in arrays. Use mirror to duplicate across a symmetry plane — both halves stay identical when you edit the source.
Shell converts a solid into a thin-walled hollow part. Select faces to remove and specify thickness. Uniform shell uses one thickness; variable-thickness shell assigns different values per face.
A slight taper (1–3°) on vertical faces. For injection molding, minimum 1° per side (2–3° for textured surfaces). For 3D printing, 2–5° reduces layer-line visibility and can eliminate supports.
Select a pull direction (usually perpendicular to the base), choose faces, and enter the angle. Apply draft before fillets — fillets adapt to tapered geometry automatically.
Replicate features parametrically — editing the original automatically updates every copy, keeping your feature tree manageable.
Copies a feature in a grid along one or two directions. Specify count and spacing per axis.
Use case: Rows of mounting holes on a chassis plate, ventilation slot arrays on an enclosure panel.
Copies a feature around a central axis at equal angular spacing. Specify count and total angle.
Use case: Bolt hole circles on motor mounts and wheel hubs, gear teeth, spoke patterns on wheels.
Reflects features or bodies across a symmetry plane. The mirrored copy stays linked to the original.
Use case: Symmetrical chassis halves, left/right brackets, mirrored mounting lugs on a center-split enclosure.
Booleans combine solid bodies by adding, removing, or intersecting material. Every hole, pocket, and joined structure relies on them.
Merges two bodies into one solid. Example: fusing a motor mount boss onto a chassis plate.
Removes the "tool" body's volume from the "target." Creates holes, pockets, and channels — e.g., cutting a shaft bore through a bearing block.
Keeps only the shared volume, discarding the rest. Useful for interference checks or complex curved surfaces from overlapping shapes.
Modifier order matters — wrong sequence causes rebuild errors. Follow this order:
Always shell before filleting internal corners. Filleting first creates complex geometry that often causes the shell operation to fail.
Starting-point values for robotics. Verify against your material, process, and load requirements.
| Modifier | Application | Typical Value | Notes |
|---|---|---|---|
| Fillet Radius | 3D-printed internal corners | 1.5 – 3.0 mm | Larger radii reduce stress risers; match nozzle diameter as minimum |
| Fillet Radius | CNC aluminum internal corners | 0.5 – 1.5 mm | Limited by endmill radius; specify slightly larger than cutter radius |
| Fillet Radius | Cosmetic external edges | 0.3 – 1.0 mm | Improves feel and appearance; does not affect strength significantly |
| Chamfer | Assembly lead-in on bolt holes | 1.0 – 2.0 mm x 45° | Guides bolts into position; size based on bolt diameter |
| Chamfer | General edge break / deburr | 0.3 – 0.5 mm x 45° | Removes sharp edges for safe handling |
| Chamfer | 3D-print bottom edge (elephant's foot) | 0.3 – 0.5 mm x 45° | Compensates for first-layer squish on FDM prints |
| Shell Thickness | 3D-printed enclosure (PLA/PETG) | 1.5 – 2.5 mm | Minimum 3–4 wall lines; thicker for load-bearing faces |
| Shell Thickness | Injection-molded ABS enclosure | 1.0 – 2.0 mm | Uniform thickness prevents sink marks and warping |
| Shell Thickness | CNC-machined aluminum housing | 1.5 – 3.0 mm | Depends on span and load; use FEA to verify for structural parts |
| Draft Angle | Injection molding (smooth surface) | 1 – 2° | Minimum for clean ejection; more for deep draws |
| Draft Angle | Injection molding (textured surface) | 3 – 5° | Texture requires additional draft to prevent drag marks |
| Draft Angle | 3D printing (tall vertical walls) | 2 – 5° | Optional; reduces layer-line visibility and may eliminate supports |
Take a simple rectangular block and transform it into a lightweight, printable electronics enclosure.