3xD 1.0-rc1 release notes
10 November 2026 · Release candidate · Superseded by 1.0-rc2
3xD 1.0-rc1 established the first tracked design baseline for the 3 mm GRP and 4 mm printed chassis. It brought together the corrected wheelbase, centred front-arm bosses, servo-saver spacers and revised M3 mounting clearances.
This is a historical release candidate. Its packs contain changed parts, not a complete car inventory. It was superseded by 1.0-rc2, which consolidates the complete current part inventories without changing the geometry. Neither publication nor CAD validation constitutes production approval.
Changes from OpenMini v1
OpenMini v1 records the saved all-printed Open Mini configuration. Rc1 brings the subsequent 3xD development into the first formal version record. The overview below describes the resulting design changes; these were developed over time rather than all introduced on the date rc1 was registered.
Two chassis setups
The original long printed chassis develops into two defined build options: a 3 mm GRP chassis and a 4 mm printed chassis, with a separate 3 mm pod plate and printed upper components. Each setup retains its own chassis, bumper and pod/bearing geometry, so builders can choose a construction method while following the matching part selection.
Reworked rear pod and bearing arrangement
The later design uses a 75 mm-wide flat pod plate, separate pod sides and a printed motor flange. Rear shoulder notches provide clearance around the separate rear body supports. Handed bearing inserts retain the different axle-height arrangements for the two chassis setups. The current backed flanged inserts remain fit-pending: flange seating and the real axle stack still require physical checks.
Updated suspension and steering interfaces
The design incorporates matched front arms and upper braces, the selected P2 side-spring cups with a continuous side-spring brace, and the rear guide with a 7.0 mm pocket, 5.8 mm hard bore and spring-lip cap. The P2 selection addresses spring retention; full movement and durability still need assembled testing. The original unreinforced A1 pod-pivot retainer is retained.
Revised servo position and bumper
Low rear-offset servo mounts place the servo case directly on the chassis and retain lateral adjustment through the chassis slots. The later bumper uses a stepped honeycomb TPU design with a flush underside and 48 mm mounting centres. These describe the revised layout and mounting arrangement; measured handling or impact-performance gains have not been established.
Final changes captured in the rc1 baseline
The following updates are the changed-part packs frozen with rc1. They sit within the broader redesign above.
Corrected wheelbase and centred front arms
The kingpin ends move 1.5 mm rearward while the chassis mounting ends and holes remain unchanged. Each rounded boss is centred on the kingpin axis, with a 6.5 mm radius and a smooth transition into the mounting end. The K1 guide, underside seating recess and double-D upper recess are retained.
The default matched front-arm pair is 4-1. Matched 4-0, 7-0 and 7-1 pairs remain optional alternatives. Use the matching upper brace for your selected arms.
Servo-saver ball-stud spacers
Two separate 1.5 mm spacers fit beneath the rear-facing M3 ball-stud shoulders. Each has a 7 mm outside diameter and 3.3 mm bore. They move the ball centres rearward to match the steering revision.
M3 mounting clearances
Smaller M3 mounting clearance holes and slots are opened to a nominal 3.3 mm. This covers the chassis and servo slots, pod plate, battery-retention parts, rear body supports, motor flange, pod sides, rear cross brace, upper kingpin braces, droop rings and rear upper spring-seat collar.
Existing adequate clearances are retained. Direct-plastic thread pilots, M2 servo pilots, kingpin guides, bearing seats and axle interfaces are unchanged. The original unreinforced A1 retainer and selected P2 spring cups remain unchanged.
What was included?
The baseline records four frozen changed-part packs:
- Centred front arms and servo-saver spacers for the 3 mm GRP chassis.
- Centred front arms and servo-saver spacers for the 4 mm printed chassis.
- M3 clearance updates for the 3 mm GRP chassis.
- M3 clearance updates for the 4 mm printed chassis.
These were partial update packs. A complete car bill of materials and consolidated manifest were still outstanding at rc1; they were subsequently added in rc2. Keep chassis-specific thicknesses and pod geometry separate.
Compatibility and reprinting
Moving from OpenMini v1: the later chassis and pod arrangements are a wider redesign. Do not treat the rc1 changed-part packs as a complete conversion kit or assume original parts are interchangeable. Use the complete rc2 inventory for your chosen chassis setup and check its fit-pending items. The targeted reuse guidance below applies to matching later 3xD parts.
- For an otherwise matching later 3xD build, the arm revision requires reprinting both front arms and fit two servo-saver spacers. The matching curved upper brace retains its printed shape and follows the kingpins rearward; the root tie and hubs can be reused.
- The arm revision preserves the chassis mounting holes. Separately check whether older chassis or other parts need the M3 clearance update.
- For the clearance update, existing parts that already fit do not need reprinting. Replace tight parts with the updated exports; do not enlarge intentional direct-thread pilots.
- Re-slice the selected STLs. Older mixed 3MF files, G-code and ZIPs can contain superseded arms or smaller mounting holes.
Spacer printing and installation
Print two spacers, or print the supplied two-spacer layout once. Use PETG, broad face flat, 0.10 mm layers including the first layer, four walls, 100% infill and no supports.
Check printed thickness, a flat seating footprint and ball-stud thread engagement. Each spacer reduces the original thread reach by 1.5 mm; use suitable longer studs if needed without bottoming out. Reset toe and check both steering locks and full suspension movement.
Validation and status
The baseline was CAD checked, with validation of the revised arms, preserved mounting geometry, spacer dimensions and local clearance changes. Frozen artifact hashes have been verified against the release register.
Physical assembled fit, spring seating, steering and suspension movement, strength and running durability were still pending. CAD dimensions and mesh checks do not establish full-car fit or race-rule compliance.
Current status: superseded. Read the 1.0-rc2 release notes for the complete inventories and the remaining fit checks.