3xD 2.8-rc2 release notes
12 November 2026 · Release candidate · Pending owner approval
Compared with complete 2.7-rc3, this release restores both front hub spring seats to 11 mm, makes the rear arm fixings blind M3 pilots, and deepens the arm identification dots. Both complete chassis kits now include those corrections and updated hardware notes.
Downloads
- Complete kit — 4 mm printed chassis
- Printed chassis single-car 3MF — 46 pieces / seven plates
- Complete kit — 3 mm GRP chassis
- GRP single-car 3MF — 44 printed pieces / six plates
Each kit contains 43 distinct STL selections, per-car quantities, hardware lists, cutting files, checksums and validation. The printed project includes its 4 mm chassis and 3 mm pod plate. The GRP chassis and pod are cut separately. Default arms are 4-1; six alternative arm STLs are supplied separately from the required print project.
Changes since 2.7-rc3
- Hub spring seats: 12 → 11 mm. The former 1 mm top addition is removed from both hubs. Axle and steering datums and selected 4.75/H0 interfaces are unchanged.
- Rear arm fixings: blind 2.7 × 6 mm pilots. Approximately 1.78 mm of roof remains. Forward arm/root-brace holes stay through. This applies to all eight arm variants, retaining their flat upper faces, K1/double-D interfaces, mounting centres and wheelbase shift.
- Arm identification dots: 0.16 → 0.48 mm deep. Diameter and positions remain unchanged.
- Hardware guidance updated. Use two M3×8 countersunk rear arm screws with no under-arm shims: nominal engagement is 5 mm for GRP and 4 mm for printed chassis, within the 6 mm pilots. Retain the forward M3×16 root-brace screws. Check actual engagement and avoid bottoming longer screws.
Replace and reuse
Replace both arms and both hubs. Ten STL selections change in each kit (eight arm choices and two hubs); 33 remain unchanged. Only one arm pair is fitted per car. The chassis, pod plate, braces, rails, body fittings, selected P2 cups, official 7 mm rear guide and cap, three-finger unreinforced A1 M3×8 retainer and setup-specific bearing carriers remain unchanged.
Front springs remain 5 mm free length × 6 mm outside diameter, with intended medium wire of 0.42 mm. Removing the raised hub seat increases the spring gap by 1 mm. Installed preload, full travel, kingpin sliding and droop retention require physical checks; the spring hardware specification itself is unchanged.
Printing and validation
Projects target P1S with a 0.4 mm nozzle and separate material plates. Precision arms, hubs and pivot use 0.08 mm layers; ordinary fittings generally use 0.16 mm; PETG saver spacers use 0.10 mm; TPU bumper and printed chassis/pod use 0.20 mm. SUNLU PA6-CF pod sides use 0.16 mm and the motor flange 0.12 mm, with six walls on their own plate. That material profile is provisional: calibrate it and use hardened nozzle and gears.
Supports are enabled locally for selected servo, bearing and rear body fittings. The combined project uses a 0.08 mm first layer; the separate spacer plate provides 0.10 mm including its first layer. Inspect bridges and toolpaths when slicing.
Frozen file hashes, current selected-source hashes, closed single-component meshes, quantities, embedded 3MF geometry, XML references, plate bounds, grounding, spacing, material assignments and per-object settings passed validation. These are unsliced projects; physical fit, screw grip, spring motion and material endurance remain to be checked.
This complete candidate incorporates the geometry of the partial 2.8-rc1 front correction packs. Earlier frozen releases remain preserved. Publication does not constitute owner approval.