3xD 1.6-rc1 release notes
10 November 2026 · Release candidate · Pending owner approval
Compared with the previous complete 1.5-rc2 kit, 1.6-rc1 simplifies the upper kingpin braces from four variants to two. Select by camber; either brace works with 4° or 7° caster arms. The remaining 41 STL selections are unchanged.
Choose the brace by camber
| Arms | Upper brace | Underside mark |
|---|---|---|
| 4-0 or 7-0 | 0° camber | No dots |
| 4-1 or 7-1 | 1° camber | One centred dot |
Default: 4-1 arms with the 1° camber brace. Fit one upper brace per car. Arm markings still have two rows: caster above camber. The brace now shows camber only.
Geometry and compatibility
Caster changes the installed angle and position of the brace. The new manufactured shapes use the former 4° nominal geometry. For 0° camber this removes only the caster marks. Compared with the former 7-1 brace, the 1° shape changes hole spacing by just 0.003318 mm and seat angle by 0.005017°. The 3.3 mm screw holes, swept outline, 8 mm rear offset and existing 1 mm top shims are retained.
Existing correctly matched braces remain usable; no mandatory reprint. Print one new brace to adopt the simpler selection and marking. Reuse the arms, lower root tie, top shims and hardware. Use 0.08 mm layers, broad face down as supplied, without supports. The single dot is 1.1 mm wide and 0.16 mm deep.
Complete paired downloads
- Download 1.6-rc1 — complete 3 mm GRP chassis kit
- Download 1.6-rc1 — complete 4 mm printed chassis kit
Each kit has 43 distinct STL selections, down from 45, with the same 46 required part instances for a default car, including fit-pending rear bearing inserts. Four old brace selections are replaced by two; all 41 other STL files and their print guidance match 1.5-rc2. Optional arms, the 0° brace and shim stock are included as alternatives. Hardware lists, cutting DXFs, manifests, checksums and validation are supplied. No G-code is included.
The kits retain the faceted battery sliders, arm dots, wider lower spring pockets and selected chassis cutouts. Front springs remain specified as 5 mm free length and 6 mm OD; no alternative wire range has yet been selected. These are inherited from earlier candidates, not new changes in 1.6-rc1. Both chassis thicknesses retain their own assembly and rear ride-height geometry.
Checks and remaining validation
OpenSCAD exports passed mesh and bed-orientation checks. Both camber shapes were checked with both caster settings on both chassis datums: M3 screw envelopes, seat rays and body-post clearance passed. Frozen input and output hashes and both complete inventories were verified.
Physical seating, spring preload, droop retention, coil bind, full steering/suspension movement and existing bearing/slider/endurance checks remain pending. Publishing the candidate does not approve it or claim racing compliance. No print job was sent.