From measured case
to printed parts.

M1 is a native FreeCAD fork with lighter open arms, two removable 120 mm fan cradles and an optional indexed airflow dam. All parts can evolve independently of the preserved ducted Rev H prototype.

Explore the six dimensioned examples and download a set ↗ · Get the fit coupon plate ↓

1. Measure the closed laptop

Measure actual width, depth from base edge to hinge edge, and maximum closed thickness. Account for feet, hinges and protrusions. The “13-inch” through “17-inch” names are examples, not universal compatibility claims.

All examples retain a 40 mm wall-to-laptop underside gap, 2 mm separate compliant contact pads and 1 mm case clearance at each side stop. They accept the modeled 120 × 120 × 27 mm fan envelope; a 25 mm fan needs a suitable compliant spacer to prevent rattle. Check the actual fan wire exit and connector.

To customize, open M1.FCStd in FreeCAD 1.1, then open M1 / Design parameters. Edit the blue laptopWidth, laptopDepth and laptopThickness cells. Recompute and Save As a new file. Gray cells are derived. The native document uses constrained Sketcher geometry and stock Part features, with no custom feature proxy needed to reopen it. Changes outside the six checked examples need renewed fit, section and print checks.

M1.1: reinforced wall junctions

Each wall pad grows from 24 to 32 mm tall and gains two 6 mm webs tapering 16 mm forward from the pad face. The webs continue through the full arm thickness to the bed face, filling the nearby window roots. Bolt centers, bores and the supplied side-down print orientation are unchanged.

Upgrading from M1.0: replace both arms, 01 and 02, and both dams, 07 and 08, if using the optional dam. The dam has a matching tapered clearance notch; all nine positions remain clear. The other sixteen parts retain their geometry.

The nominal arm pair adds 13.54 g of solid CAD. The complete sliced set adds 12.50 g and 17 m 36 s compared with M1.0. The larger section is a geometric result, not a tested strength multiplier. Layer adhesion, warm ASA creep, fasteners and anchors still require physical qualification. Read the native section comparison and assumptions.

2. Print the coupon, then the set

1. Extract the coupon ZIP. In OrcaSlicer, select Bambu P1S, 0.4 mm nozzle and the profile for your actual ASA spool. Import 00_fit_coupon_plate.3mf as geometry. Keep its orientation and scale.
2. Use 0.20 mm layers, 6 walls, 6 top and bottom layers, 100% rectilinear fill of the deliberately open CAD, Arachne walls, 8 mm outer brim and supports off. The comparison used the bundled Bambu ASA profile; temperatures and drying must follow the actual spool.
3. Preview every layer. The eight-piece coupon reproduces the two-rung arm/carriage joint, keeper, fan-hanger slot region and one fan-cap socket from the actual native parts. Remove brim and burrs, seat the key through both receiver pieces, then insert and remove the keeper. Check cap-pin insertion, crown retention and repeatable withdrawal. Adjust the shared clearance or crown interference only after measuring the printed result, then regenerate and recheck.
4. For the complete assembly, print one each of 01–08 plus 21_all_hardware: nine plates. The hardware plate contains all twelve parts numbered 09–20. Those individual files are alternatives for replacements; do not also print them. STL, STEP and geometry-only 3MF are alternatives for the same part.
5. Keep the baked orientations: arms outer side down and diagonal; cages grille down; caps front face down; dams lip down; keys flat outer plate down; pins button down with split tips up. STEP files are centered or placed on the P1S bed and already at Z=0. Do not auto-orient or scale.

Optional dam: omit parts 07, 08, 11, 12, 15 and 16. Print 01–06 plus 22_hardware_without_dam, for seven plates. Plate 22 contains only the eight hardware parts needed without the dam; use it instead of plate 21. The assembled STEP is for inspection, not a printable plate.

The included standard 3MF files contain geometry and orientation, without printer settings or G-code. Separately labeled Orca preview archives contain embedded G-code and are for inspecting the reviewed paths; re-slice for your actual spool. No print was sent to a printer.

3. Assemble and set the dam

1. Confirm both arms match your measured case and the laptop’s contact and port layout. Add the separate compliant pads to the shelf, rear and front contact seats. Use fasteners, washers and wall anchors suited to the actual wall and load; the printed pads have 7.2 mm clearance bores. This project does not qualify a particular wall anchor.
2. Mount the arms level at the native spacing. Their outboard face spacing is case width + 8 mm. Each wall-bore center is 18 mm inboard of its arm’s outer face, so left-to-right wall-bore spacing is case width − 28 mm. Vertical bore spacing is armHeight − 34 mm; use the selected native preset or a measured template rather than mixing dimensions from different examples.
3. Fit each fan cradle to the lower two arm slots. Insert its two-rung key from the outboard side, through arm and carriage. Insert the keeper from above through the exposed key tips. The D-flat on its button faces the carriage. Seat the crown fully; the keeper prevents withdrawal and does not replace the key’s load-bearing tongues.
4. Slide each fan into its open rails with airflow aimed up the rear gap. Follow the fan’s airflow arrow; the model only provides its mechanical envelope. Route the cable through the open retainer notch, fit the retainer cap and install its two printed pins.
5. If using the dam, choose the same lower-rung index from 0 to 8 on both arms. The key engages that rung and the rung two positions above it: 24 mm between tongues on a 12 mm ladder. Fit both halves with their keys and keepers. To adjust, support the dam, remove the keeper, withdraw the key, move to the desired index and reinstall. There are nine positions over 96 mm.
6. Confirm the laptop can lift at least 43 mm before moving forward past the front tines. Check its vents, exhaust and ports against the actual dam position. CAD removal checks used rectangular case and fan envelopes; cables, flexible pads and detailed laptop protrusions require your physical check.

Start with a supported assembly close to a safe surface. Check seating and retention before putting the laptop’s weight on the mount. Review deformation and keeper seating after the first warm operating period and over time. Airflow direction is a design intent; M1 has no cooling benchmark or CFD result.

4. Read the comparison correctly

Both used OrcaSlicer 2.4.2, the same base P1S/ASA process and supplied orientations. Rev H uses its required 180° cross-slot bridge override; M1 uses automatic bridge direction. M1 uses one combined hardware plate; the historical Rev H layout prints four pins individually. Totals include each plate’s estimated startup and brim. They compare complete new sets, including arms, and exclude fans, pads and wall fasteners. The nominal M1 total is 66.2% less filament and 53.8% less estimated time. If your Rev H arms are already printed, its remaining twelve parts are approximately 634.69 g and 20 hours under this layout.

The native nominal M1 volume is 396.40 cm³, or 416.22 g at an assumed density of 1.05 g/cm³. That is a separate solid-volume calculation; slicer mass uses its filament profile and generated paths. Do not mix the two methods.

5. Evidence and remaining qualification

Six presets × nine dam indices passed native checks: valid single solids, fully constrained sketches, no unintended overlap, 0.30 mm intended interface gaps, no wall intrusion, and clear case/fan envelopes. Laptop and fan removal were sampled at both end positions; they are not continuous motion proofs. Each preset was saved, reopened and rechecked. Every individual print and hardware plate passed closed-mesh, STEP roundtrip and P1S bed/brim/cutter checks.

The nominal Orca path screen found no disconnected floating components and a maximum bridge-tagged span of 3.02 mm. The all-feature screen also identifies overhang-wall spans up to 8.99 mm at the fan hanger and 6.12 mm at the dam slots. The coupon includes both interfaces in their full-part build directions. It buffers actual extrusion paths by their reported width and measures unsupported portions against the previous layer. It does not prove same-layer anchoring order, adhesion or physical sag. The independent section review uses an assumed 3 kg case, twice gravity and equal arm loading to report nominal stress demand; it supplies no material allowable or certified load rating.

Release evidence and size-specific estimates · Section calculations and assumptions · Native source, validators and export scripts

Ducted Rev H has its own corrected cross-slot bridge review. The old 836,278-cell Rev F CFD remains labeled as exploratory baseline evidence. It is neither a Rev H nor a Minimalist cooling result. The separate Rev H commissioning report has failed expanded mesh checks and only 0.0203084 ms completed of the planned 2 ms; shedding, Bernoulli suction and validation are not established.