What is a cantilever snap fit?

A cantilever snap fit is a flexible beam with a hook at the end that deflects during assembly and snaps into a matching recess. It is the most common snap fit type used in 3D printing for enclosures, lids, and clip connections.

How do I prevent snap fits from breaking?

Keep the strain below the material allowable limit. Longer, thinner beams deflect more without high strain. Add fillets at the base to reduce stress concentration. Print so the beam bends parallel to layers, not across them.

What undercut depth should I use?

For PLA, keep undercut to 0.5-1.0mm for a 15mm beam. Nylon allows 1-2mm undercut for the same beam length. The undercut determines how far the hook engages — deeper = more secure but harder to assemble and more strain.

Should snap fits be printed flat or upright?

Print the beam so it deflects parallel to layers (the beam lies flat on the bed). This way, the bending does not try to delaminate layers. If the beam must bend across layers, use higher print temperatures for better layer adhesion.

3DPrintCalcs

Snap Fit Calculator — Cantilever Snap Dimensions

Calculate cantilever snap fit dimensions for secure clip connections.

Beam Length

Cantilever length

Beam Thickness

Beam thickness in the bending direction. Thinner beams strain less for a given undercut — the strongest lever you have to stay within material limits.

Beam Width

Width of the cantilever beam (into the page). Wider beams are stiffer and need more insertion force, but do not change peak strain.

Undercut Depth

Hook engagement depth

MaterialSelect a material or choose Custom to enter modulus and strain values

How We Calculate This

Snap Fit Formulas

Max strain = 1.5 x Thickness x Undercut / Length²
Deflection force = (Width x Thickness² x Modulus x Strain) / (6 x Length)
Insertion force = Deflection force x (tan(angle) + friction) / (1 - friction x tan(angle))

The strain must stay below the material's allowable strain to prevent breakage. Longer beams distribute strain over more material, allowing larger undercuts. PETG and Nylon are more forgiving than PLA for snap fits. The modulus and allowable strain are print-dependent — infill, wall count, layer orientation and moisture all shift the real values, so treat the result as a design starting point and prototype before committing.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify settings with test prints before committing to final prints.