- Form 4 Design Rules
Design it right the first time. Skip the reprint.
11 Rules
Dimensional limits that prevent failures
±0.15%
Tolerance on 1–30mm features
50 µm
Resolution these guidelines are tested at
0 Guesswork
Every value backed by Formlabs test data
- Why Design Rules Matter
A print failure is usually a design decision, not a printer fault
- The Rulebook
11 dimensional limits for a clean first print
Rule 01
Minimum Supported Wall Thickness
0.2 mm
A wall connected to others on two or more sides. Thinner walls risk warping under peel forces.
Rule 02
Minimum Unsupported Wall Thickness
0.2 mm
A wall connected on fewer than two sides. Below this, expect warping or full detachment.
Rule 03
Max Unsupported Overhang
5.0 mm
Beyond this length, a horizontal feature won't fully form without added support structures.
Rule 04
Min Unsupported Overhang Angle
10° from level
Shallower angles risk breaking off during the peel step of printing.
Rule 05
Max Horizontal Span/Bridge
29 mm
The maximum distance between two supports for a 5×3 mm beam before failure becomes likely.
Rule 06
Min Vertical-Wire Diameter
0.3–0.6 mm
0.3 mm supports up to 7 mm of height; 0.6 mm supports up to 30 mm before deforming.
Rule 07
Minimum Embossed Detail
0.1 mm
Raised surface details like text or logos smaller than this may not be visible on the finished part.
Rule 08
Minimum Engraved Detail
0.15 mm
Recessed details narrower or shallower than this may fuse with the surrounding surface.
Rule 09
Minimum Clearance
0.4 mm
The gap needed between two moving or mating parts (like gear teeth) to avoid fusing together.
Rule 10
Minimum Hole Diameter
0.5 mm
Holes smaller than this in any axis risk closing over during printing.
Rule 11
Minimum Drain Hole Diameter
0.75 mm
Required on fully enclosed cavities so trapped resin can escape and avoid a cupping blowout.
- Beyond Individual Features
What accuracy to expect across your whole part
| Feature Size | Tolerance | Lower Limit |
|---|---|---|
| 1–30 mm | ±0.15% | ±0.02 mm |
| 31–80 mm | ±0.2% | ±0.06 mm |
| 81–150 mm | ±0.3% | ±0.15 mm |
- Generation Over Generation
How much more accurate is Form 4 than Form 3?
| Feature | Intended Size | Form 4 Actual | Form 3 Actual |
|---|---|---|---|
| Min. supported wall | 0.2 mm | 0.17 mm | 0.25 mm |
| Min. unsupported wall | 0.2 mm | 0.18 mm | 0.26 mm |
| Max. unsupported overhang | 5.0 mm | 5.00 mm | 5.03 mm |
| Min. vertical wire (7mm) | 0.3 mm | 0.20 mm | 0.35 mm |
| Min. embossed detail | 0.1 mm | 0.13 mm | 0.24 mm |
| Min. hole diameter | 0.5 mm | 0.42 mm | 0.26 mm |
| Min. drain hole | 0.75 mm | 0.91 mm | 0.90 mm |
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