Fast CRT: the quickest way to find your exposure window
This page explains the fastest practical way to use the 3Dresyns® Curing Rate Table logic for first exposure selection.
Purpose: help users move away from random guessing and identify a practical working interval with minimal measurements.
Fast CRT is designed to help users quickly bracket the likely working interval for standard-layer exposure before deeper optimisation.
Predefined printer settings may appear convenient, but they are fundamentally unreliable in photopolymer additive manufacturing due to printer-to-printer variability, non-uniform light distribution, optical aging and dependence on fixed layer thickness assumptions.
To understand why 3Dresyns® uses calibration-based control instead of fixed universal settings, see:
Technical bulletin: Printing settings vs Curing Rate Control (CRT) →
1) Why use Fast CRT
Because guessing exposure is usually slower
Many users try to find exposure by repeatedly editing slicer values without a clear method. Fast CRT is a more reliable starting route because it links exposure time to real cured thickness and real green-state behaviour on the actual printer.
The goal is not maximum cure. The goal is to find a practical exposure window that supports reliable printing at the chosen layer height.
2) The recommended Fast CRT starting points
Start with 5 s, 10 s and 15 s
For rapid implementation, the recommended first Fast CRT points are:
- 5 s
- 10 s
- 15 s
These three points often give enough information to understand whether the system is still under-cured, entering the likely working interval or already moving towards a higher-cure region.
3) How to run Fast CRT
Use a short structured sequence
Measure cured thickness at 5 s, 10 s and 15 s
Use the selected printer and the real resin system under the intended practical conditions.
Evaluate cured thickness and green-state behaviour
Do not record thickness only. Also consider whether the cured material is weak, acceptable or excessively strong for the intended workflow.
Identify the likely working interval
Use these first three points to understand where the practical exposure window is likely to sit.
Add one or two extra points only where they matter
Once the likely interval is visible, add one or two extra measurements in that interval rather than building a long CRT from the start.
4) How to extend the Fast CRT
Add only the points that improve your decision
If the system looks fast or highly reactive
- add one or two points between 1 and 5 s, or
- add one or two points between 5 and 10 s.
If the system looks slower or more demanding
- add one or two points between 15 and 20 s, or
- continue further only if the practical working interval clearly lies beyond 15 s.
Fast CRT is most useful when it helps you avoid unnecessary measurements while still identifying a practical window.
5) How to interpret the result
Look for a usable working interval, not for the highest possible cure
Likely under-cured behaviour
- weak or tender green state,
- insufficient cure for reliable layer formation,
- higher risk of failure during peeling.
Likely useful working interval
- sufficient cured thickness for the selected layer strategy,
- acceptable green strength,
- no obvious sign of excessive cure.
Likely excessive cure
- strong cure beyond what is practically needed,
- higher risk of unnecessary adhesion,
- higher risk of detail loss and over-cure effects.
6) What to do after Fast CRT
Move from exposure selection to print validation
Once a likely exposure interval has been identified, validate it with the first 3Dresyns® calibration geometries.
- Print 3Dtest1 first.
- Then validate with 3Dtest2.
- Only then decide whether deeper CRT mapping or further optimisation is needed.
7) Useful next pages
Use Fast CRT together with these documents
Governing principle
Fast CRT is the quickest structured route for identifying a practical exposure window on the real system without pretending that a fixed universal setting exists.
Need technical support?
For support with CRT interpretation, exposure selection or technical implementation, contact info@3dresyns.com.