Week 3: Computer-controlled cutting

Individual assignment: parametric hex snowflake kit

Task and why a snowflake kit

The individual brief asks for a parametric construction kit that accounts for laser kerf and can be assembled in more than one way without glue. I wanted something small enough to iterate on one sheet of plywood but still teach me the same lesson as a big press-fit project: if board thickness or kerf changes, I should change one variable, not redraw every slot by hand.

I chose a six-fold snowflake: an inscribed hexagon hub with six rectangular spokes that slot into matching partners. Chamfers on the tabs make the first push-fit less brutal. After the cut I could stack the pieces flat, fan them into a star, or build the full 3D snowflake shown in the hero photo—it is the same kit, different assemblies.

How this page meets the assignment

Mapped to the Fab Academy computer-controlled cutting checklist:

Parametric design in Onshape

I modeled entirely in Onshape as a single sketch driven by variables. The screenshots follow the order I actually built it: hex hub first, then spokes sized with kerf, then chamfers, then export. The feature tree names I kept are diameter (inscribed hex hub, I started at 40 mm), kerf (spoke tab width tied to group comb results), length (overall spoke arm), and chamfer_distance1 / chamfer_distance2 (joint edge chamfers so press-fit assembly is less brutal than square corners).

Step 1 — inscribed hexagon hub

I sketched a regular hexagon from an inscribed circle and bound its size to diameter so the whole hub scales together.

Step 2 — six spokes with kerf and length

I added six rectangles for the snowflake arms, set width = kerf and length = length, then constrained each rectangle to the hex hub with coincident and center constraints so the pattern stays symmetric when I nudge parameters.

Step 3 — chamfer variables and geometry

Square slot corners fought me on the first dry fit, so I introduced chamfer_distance1 and chamfer_distance2 and applied chamfers to the joint edges instead of redrawing the slots.

Step 4 — DXF export for the laser

From the finished sketch I exported a flat DXF for the lab laser workflow (same file linked under Design files). I checked scale and units in the export dialog before walking the file to the cutter PC.

Laser cutting

I transferred the DXF to the laser workstation, picked cut settings for our approved plywood (power/speed from lab notes and the group characterization table), and ran the job. The clip below is the cut on the machine. Useful when I need to remember engrave-vs-cut order and how long six duplicate spokes take on one sheet.

Assembly and finished snowflake

Off the bed I deburred tabs with a knife, then pressed pairs together starting from the hub. Chamfers helped more than I expected. The square-edged trial in CAD felt fine until real kerf tightened the slots. The assembled star and the final 3D snowflake are different views of the same kit.

Finished 3D snowflake

Vinyl cutter: one hex puzzle piece on Cricut Explore

The individual brief also asks me to cut something on the vinyl cutter. I reused the same parametric hex kit rather than downloading a sticker file. From the flat hex-snowflake-kit.dxf I isolated one hex interlocking puzzle piece, a single hub-and-tab unit from the snowflake layout — and cut only that piece on blue heat-transfer vinyl (iron-on stock). I did not run a separate paper or cardstock cut; this job is my vinyl-cutter deliverable for the week.

Machine and software

The bench unit is a Cricut Explore with a physical Smart Set material dial and front-panel Load/Unload and Go buttons. I drive it from Cricut Design Space. I downloaded and install from that page, sign in, pair the Explore over USB or Bluetooth, then send jobs from the Make It screen. Design Space is the CAM layer: it turns my uploaded vector into mat layout, blade passes, and the on-machine prompts.

Materials

I cut blue heat-transfer vinyl (iron-on sheet on its carrier) face-up on a StandardGrip green mat, using the Explore’s Fine-Point Blade for the through-cut. The vector came from the same Onshape export as the laser kit: hex-snowflake-kit.dxf; I isolated one puzzle piece from the full snowflake layout.

Operation steps (Design Space → machine)

Screenshots follow the order I actually walked through: import the DXF, scale on the canvas, pick mat loading, lay out on the virtual mat, confirm material and blade, then run the physical cut.

Step 1 — Upload the DXF

In Design Space I used Upload → Upload image/file and selected hex-snowflake-kit.dxf. The importer brought in the full snowflake layout; I kept only the geometry I needed for one puzzle piece in the next step.

Step 2 — Isolate one puzzle piece and scale

I deleted the extra snowflake arms and kept a single hex puzzle piece in the top-left of the grid, then set dimensions to about 9.87 cm × 8.55 cm so it fit inside the 12 in mat width with room for the rollers to grip the edges. Layer operation stayed Basic cut.

Step 3 — Choose “on mat” loading

On Make It I chose On mat (vinyl / iron-on workflow), not the card mat, and confirmed the 30.5 cm × 61 cm mat size.

Step 4 — Prepare mat layout

The prepare screen shows the single puzzle piece nested in the top-left of the virtual mat (black cut area on the mat preview). One copy, mirror off.

Step 5 — Material preset and blade prompts

With blue heat-transfer vinyl on the StandardGrip mat, Design Space walked me through the Explore checklist: set the Smart Set dial to the iron-on / vinyl preset, load the Fine-Point Blade in clamp B, insert the mat until the rollers catch, press Load/Unload, then the flashing Go button when the prompt unlocked.

Step 6 — Cut on the machine

The clip is the Explore during the through-cut: rollers advance the mat, the blade traces the hex tab outline and slot notches in the heat-transfer vinyl. I watched the first corner before walking away. Thin iron-on can lift if the mat is dusty or grip is weak.

Step 7 — Final output

After the cut I lifted the blue hex interlocking puzzle piece off the mat on its carrier sheet. The rectangular slots match the kerf-aware tabs from the same parametric sketch — a quick check that my DXF export survived a second cutter even when I only cut one piece from the layout.

Design files (download)

Flat layout exported from Onshape: hex-snowflake-kit.dxf. If the browser opens the DXF instead of downloading, use Save As.

Reflection

Building the kit in Onshape forced me to treat kerf as a real dimension, not a note on the group page. Linking slot width to kerf meant when the group comb test nudged my value, I could regenerate the DXF instead of hand-editing six slots. Chamfers were the other lesson: parametric sketches only stay pleasant to assemble if you plan for entry angles, not just nominal width.

Running one puzzle piece on the Cricut Explore taught me that “vinyl cutter” in the syllabus really means knife plotter + CAM software, not a different geometry language. Design Space handled the import, but I still had to isolate a single piece from the full snowflake DXF and watch mat margins before sending the job. Tighter numeric rows in the group laser table (power/speed/kerf for this plywood lot) are still on my list. For the final project I may reuse the hub-and-spoke pattern for decorative iron-on panels once both cutters’ kerfs are logged side by side.