Week 3 — Computer Controlled Cutting¶
This week I explored FreeCAD and LightBurn to understand the workflow of computer-controlled cutting.
I also learned how to prepare and configure the laser cutting machine before fabrication.
Parametric Design¶
During this stage, I created a parametric model in FreeCAD using Spreadsheet parameters.
Steps:
- Created a Spreadsheet
- Defined material thickness
- Added kerf parameter
- Defined joint width as a formula
Joint width was calculated using:
joint width = material thickness − kerf
Laser Parameter Testing¶
I performed laser parameter tests by varying speed while keeping power constant.
The goal was to understand how laser speed affects material cutting behavior and surface quality.
Calibration Test (11 Rectangles) — Group Work¶
During group work, Ani and I designed a calibration test consisting of 11 rectangles (10 mm each), cut as a single continuous geometry.
Expected total length:
110 mm
Measured result:
107.77 mm
Problem Detection¶
The measured dimensions showed significant deviation from the design.
We realized that the issue was not only related to laser kerf.
The results suggested a possible machine calibration problem, especially related to X/Y axis scaling.
The dimensional deviation indicated a machine calibration issue rather than only kerf loss.
Temporary Adjustment¶
To continue testing, we applied a temporary scaling compensation in LightBurn to correct dimensional deviation.
A correction factor was calculated using the formula:
Scale factor = 100 / 98.058 ≈ 1.0198
This adjustment improved dimensional accuracy but was considered a temporary solution rather than a final machine calibration.
Kerf Calculation¶
After improving dimensional accuracy, we calculated the laser kerf.
Expected total length: 110 mm
Measured total length: 107.77 mm
Total material loss:
110 − 107.77 = 2.23 mm
Number of cuts between rectangles: 10
Kerf estimation:
Kerf = Total Loss / (Number of Cuts × 2)
Kerf ≈ 2.23 / (10 × 2)
Kerf ≈ 0.11 mm
This kerf value was later used to improve parametric joint design.
Result¶
After compensation and kerf integration into the parametric model, cutting accuracy improved significantly.
Press-fit joints behaved more predictably and dimensional consistency increased.
Reflection¶
This week helped me understand that digital fabrication is not only about design, but also about machine calibration and measurement.
I learned that:
- machine accuracy must be verified
- kerf directly affects joint fitting
- parametric modeling simplifies iteration
- measurement is essential in fabrication workflow
The iterative process (design → cut → measure → adjust) shifted my approach from simply using machines to understanding and calibrating fabrication systems.