Choosing resin support tips is a balancing act: too thin and supports snap off the build plate mid-print; too thick and they crater the model when you remove them. This tool estimates the break-away force for a given tip size and resin so you can pick the smallest tip that still holds.
How it works
A support always breaks at its weakest cross-section — the contact tip. The force to snap it is the tip’s area multiplied by the cured resin’s tensile strength.
A = (π / 4) × d² tip cross-section in mm²
F = σ × A × notch_factor break force in newtonsdis the tip diameter in millimetres.σis the cured resin’s tensile strength in MPa (which equals N/mm²).- The notch factor (~0.6) accounts for the tip being a deliberate stress riser that fails earlier than a clean tensile bar would.
Because force grows with the square of diameter, a 0.6 mm tip is roughly four times harder to remove than a 0.3 mm tip — and leaves a much larger scar.
Why tip diameter affects both printing and removal
The same tip must survive two very different mechanical events: the peel force during printing, and the manual break-away force applied after curing is complete.
During printing, each layer is pulled off the FEP (or nFEP) film at the bottom of the vat during the peel cycle. This creates a rapid tensile load on every support tip simultaneously. The peel force per tip depends on the model’s cross- section at that layer, the film type, and the lift speed and distance — but it typically exceeds the manual removal force, which is why supports that seem strong enough to remove cleanly by hand can still fail mid-print on large, heavy models. Increasing density (more supports, smaller spacing) distributes peel force across more tips so no single tip bears too much.
After printing, the cured resin is at its full strength and the break-away force must overcome that. Larger tips need more force, leave larger surface scars, and are harder to clean up. The goal is a tip just large enough to survive the worst peel event the model produces.
Resin type and how it changes the calculation
Cured tensile strength varies substantially across resin categories:
- Standard resins (low-tack, general hobby resin) have moderate strength. Tips in the 0.3–0.5 mm range typically break off cleanly.
- Tough / ABS-like resins are significantly stiffer and stronger when cured. The same 0.5 mm tip requires noticeably more force to remove and leaves a deeper nub. With these resins, consider 0.3–0.4 mm tips and more of them.
- Flexible and rubber-like resins have much lower tensile strength. A 0.5 mm tip in flexible resin breaks almost by hand — too easily for heavier parts. Increase to 0.6–0.7 mm or use more supports to prevent mid-print snap-offs.
- Engineering and dental resins are the hardest to remove cleanly. Use the smallest tip diameter your print stability will tolerate.
Override the tensile strength field with the value from your resin’s datasheet for the most accurate force estimate.
Tips and notes
- Prefer many small-tip supports over a few thick ones: each holds less, but together they resist the peel force without leaving big marks.
- Strong resins (tough, engineering, dental) magnify removal force; use smaller tips with them.
- If supports snap during printing, raise tip diameter slightly or increase support density rather than over-curing.
- After removal, the residual nub can be sanded or kissed with a UV pen and trimmed — smaller tips leave less to clean up.