Week 3 — Computer-controlled cutting

This week’s topic: Computer-controlled cutting. I redid my individual documentation so it matches the actual laser job: an Elsa / “ISA Innovation Centre” tech–music violin wall bracket cut from approved plywood in LaserMaker, with evidence stored under images/week02/ (process stills, masks, and clips) so filenames line up with the design order. The earlier draft mixed in the wrong photo set; this page follows the captures that already say what each step was. CAD prep also appears in Week 2; here the emphasis is the machine-controlled cut, the music-symbol library I reuse across layouts, and masked spray paint after the part comes off the bed.

Individual assignment — laser-cut violin bracket (corrected)

Task and what I was curious about

I needed a wall bracket that reads as STEM + music signage but still survives shop handling: routed circuits and clefs, a real metal hook, and a finish that does not flood the engraved texture. The mistake in my first write-up was narrating a different photo batch; the sequence below is the one I actually executed, and each screenshot or photo filename tags the stage (week02-design-01…04, machine, post-laser, mask passes).

Concept — flat hanger, hook load path, and clean graphics

The part is a single plywood panel: engraved artwork on the face, cutouts for hardware, and a commercial U-hook bolted through after I trust the geometry. Magnets or pegboard variants are optional mounting strategies; what mattered for this cut was keeping inner features wide enough to engrave cleanly and leaving registration edges for paint masks I cut from thin scrap on the same machine.

2D workflow in LaserMaker (matches the screenshot filenames)

Design 1 — dimensions, hook logic, decoration fields

I locked the outer board, the hook zone, fastener holes, and where the “busy” graphics can live without breaking minimum feature rules—before booleaning myself into a corner.

LaserMaker screenshot: dimensions and decoration plan for violin bracket — Figure 1: `week02-design-01-dimensions-decoration` — sheet size, hook pocket, and the decorative fields sketched first.

Design 2 — boolean union for one outer silhouette

I merged ornament and frame with union so LaserMaker sees one closed cut contour—fewer duplicate paths when I assign colors to cut vs engrave.

LaserMaker screenshot: union outline for violin stand — Figure 2: `week02-design-02-union-outline` — single coherent outer profile.

Design 3 — circuit texture + stylized graphics

On top of the silhouette I layered PCB-like traces and flatter strokes that sell the tech look, checking that skinny vectors will engrave instead of vanishing in soot or overburn.

LaserMaker screenshot: circuit traces and stylized decoration — Figure 3: `week02-design-03-circuit-anime-decoration` — graphic pass after the union step.

Music-symbol motif library (separate project file)

Staff fragments and note heads repeat across the piece; instead of redrawing them I keep a small music-symbol “素材库” as its own LaserMaker archive music-symbol-motif-library.lcpx. In the main bracket layout I import or copy-merge motifs from that library whenever I need another flourish—same note geometry, predictable spacing, less cleanup. Both the library and the assembled board are linked under Design files below (canonical copies live next to Week 2).

Design 4 — laser-cut spray masks nested with the bracket

For spray paint I drafted mask plates in the same CAD session: closed vectors that register on the real board and shield everything that should stay bare wood for a given color pass. The masks were cut from thin scrap on the same cutter; I run orange with mask 1, peel, register mask 2, then spray black so the two accents never fight in the same region.

LaserMaker screenshot: spray mask layout paired with bracket art — Figure 4: `week02-design-04-spray-mask-layout` — mask geometry paired with the panel before sending the job.

Machine run — engrave-then-cut, with video

On the lab CO₂ machine I set focus for the sheet thickness, pinned the panel flat (large corner magnets on honeycomb), and ran engrave/marking before through-cuts so small islands do not lift mid-job. I kept airflow on and paused if smoke obscured the beam path. The clip below is the screen capture I keep next to the still from the bed.

Video — week02-laser-cutting-process.mp4 (cut workflow screen capture).

Laser cutter working on violin bracket plywood on honeycomb — Figure 5: `week02-lasermaker-cutting-on-machine` — in-progress still on the honeycomb.

Post-laser — inspection, hardware fit, clearcoat

Off the bed the panel was warm and dusty; I brushed char without sanding through shallow engraving, dry-fitted the metal bracket, then added a light clear acrylic mist so handling does not embed fingerprints in the grain before the color passes.

Violin bracket panel fresh off laser before hardware — Figure 6: `week02-post-laser-fresh-off-machine` — first inspection.

Metal bracket installed on laser-cut wooden panel — Figure 7: `week02-post-bracket-mounted` — hardware check before paint.

Clearcoat on wooden bracket before masked color — Figure 8: `week02-post-clearcoat` — thin clearcoat before masks.

Masked spray paint — physical masks cut on the same laser

Why masks: rattle-can orange/black is fast, but overspray would muddy the engraved lines. Laser-cutting mask inserts from cardstock/thin ply gives crisp edges: tape each mask flat, keep coats light, and stop immediately if an edge lifts so paint cannot sneak under. I sprayed orange first with mask 1, peeled, aligned mask 2, then laid down black.

Laser-cut mask piece one for orange spray — Figure 9: `week02-mask-piece-01` — first mask plate.

Laser-cut mask piece two for black spray — Figure 10: `week02-mask-piece-02` — second mask plate.

Spraying orange through first laser-cut mask — Figure 11: `week02-finish-mask1-spray-orange` — orange pass, ventilated.

Spraying black through second laser-cut mask — Figure 12: `week02-finish-mask2-spray-black` — black pass after peel and re-register.

Finished piece

The last photos close the loop: hero shot of the painted bracket and a wider context frame on the wall rig.

Finished painted laser-cut violin wall bracket — Figure 13: `week02-finished-product` — final assembly after masked color.

Violin bracket in display context — Figure 14: `week02-in-use-context` — how it reads beside other shop work.

Extra clips (compression tests for the site)

For GitLab Pages weight limits I also exported shorter versions of the same material: week02-video-before-compression.mp4 and a downscaled week02-video-after-480p.mov. Screenshots of the QuickTime / resolution workflow sit in images/week02/media-compression/ and are narrated on Week 2 — compressing assets for uploads if you need the step-by-step dialog captures.

Design files (download)

Native LaserMaker (.lcpx) archives—the main board and the reusable music library. If the browser opens instead of downloading, use “Save as” from the menu.

Reflection

Fixing this page forced me to admit the old figure set told a different story than my masks-and-hook workflow. Treating the music library as a real asset (not one-off vectors) made the layout faster; cutting paint masks with the same tool chain meant registration matched CAD instead of hand-trimmed tape templates. What I still owe the class repo is tighter linkage to measured power / speed / kerf for this plywood lot—that belongs next to the group characterization table, not only “looked good on the day.”

Group assignment

Guangzhou (Chaihuo) — group documentation: laser-cutter characterization, joint tolerance tests, and GitLab-based collaboration.

Abstract

After completing the lab’s laser safety training, the group documents how the local laser cutter behaves in practice: focus setting versus cut quality, usable power levels, speed for cut versus mark, pulse frequency or effective scan rate (as applicable to the machine), measured kerf, joint clearance for press-fit or slot joints, and material types the site approves. The report adds a laser tolerance study—for example a comb test or equivalent spacing sweep—to find reliable gaps for finger joints and inlays. Photos and short video of representative cuts and tests are committed through the lab GitLab workflow (fork → branch → merge request), and the Chaihuo group site shows how that review and versioning ties to the physical lab work.

1. Safety training and approved use

Summarize the training completed, who signed off, and any lab-specific rules (ventilation, materials ban list, fire watch, supervision).

2. Machine characterization

Record focus, power, speed, frequency/rate, kerf, joint clearance, and materials in a table; note how each was measured (calipers, test coupons, microscope photos, etc.).

Parameter	Notes / method
Focus	Relate focus setting to edge quality; record nominal vs. best visual cut.
Power / speed / rate	Ranges used for cut vs. mark; align with control UI labels for your machine.
Kerf	Measured from test cuts or comb coupons (calipers / photo overlay).
Joint clearance	Press-fit or slot joints: gap that fits reliably on this cutter.
Approved materials	List materials allowed at Chaihuo for laser processing.

Lab photos (cutting workflow)

Plywood stock placed and aligned on the laser work area — Figure 1: Stock placed and aligned on the work area.

Laser machine powered on at the bench — Figure 2: Power-on and bench state.

Laser cutter control software or panel showing job parameters — Figure 3: Operator UI — verify power, speed, and job parameters for your machine.

3. Tolerance testing (e.g. comb test)

Describe the test file, parameter sweep, and how the group chose “good” slots/fingers; use the photos below to annotate kerf, joint clearance, or comb coupons.

Laser cutting job in progress — Figure 4: Cut in progress.

Finished laser-cut part on the bed — Figure 5: Finished part — add caliper readings or close-ups of tolerance coupons.

4. Collaboration: GitLab and the Chaihuo site

Briefly document fork, merge request, review, and where the narrative or embeds appear on the group documentation site.