Architecture Decision Records

Amalgam documents every major engineering decision as an Architecture Decision Record (ADR). Each ADR captures context, alternatives considered, rationale, and consequences.

Reading Order

If you’re new to Amalgam, read in this order:

  1. ADR-000: Engineering Philosophy — Core principles: Mass, Software, Gearing, trade-offs
  2. ADR-025: Multi-Frame Architecture — Scaffold, Mill, Lathe paths (all on MDF base)
  3. ADR-026: Donor Fitness & Constraints — Bed size, Z-height, stability limits
  4. ADR-021: Dual-Rod Motion System — Dual 8mm vertical stacking
  5. ADR-012: Mainboard & Host Architecture — Electronics paths, dual-MCU config
  6. ADR-019: Pitan Extruder — Single-drive, 3:1 geared
  7. ADR-004: E3D V6 + CHT — Hotend selection

Foundational

ADR Title Status
000 Engineering Philosophy (20 Years of RepRap Wisdom) Accepted
001 M10 Threaded Rod Skeleton Accepted
002 Greg’s Wade Geared Extruder Archived (see ADR-019)
003 Smooth Rods vs Linear Rails Superseded (see ADR-021)
004 E3D V6 Hotend with CHT Nozzle Accepted

Motion & Leveling

ADR Title Status
005 Triple-Z Kinematic Leveling Accepted
006 Z-Probe Selection (Legacy) Archived (see ADR-014)
009 Modular Puck & Spider Bed System Accepted
010 Floating Z-Puck System Accepted
020 Dual-8 Scavenger Variant Superseded (see ADR-021)
021 Dual-Rod Motion System Accepted
022 Linear Bearing Selection Accepted
023 Z-Drop Architecture Accepted
024 Heated Bed Size Selection Accepted
025 Multi-Frame Architecture Accepted
026 Donor Fitness & Frame Constraints Accepted
027 Build Plate Surface Selection Accepted
028 Target Filament Selection Accepted
029 Brand Palette & Visual Identity Accepted

Foundation & Electronics

ADR Title Status
007 CAN Bus Architecture Accepted
008 Spider Bed Support System Accepted
011 Laminated Plinth Baseboard Accepted
012 Mainboard & Host Architecture Accepted
013 Driver & Endstop Strategy Accepted
016 Electronics & PSU Mounting Strategy Accepted

Tooling & Probing

ADR Title Status
014 Z-Probe Selection (SuperPINDA vs BLTouch) Accepted
015 Single Toolhead Architecture Accepted

Software & Tooling

ADR Title Status
017 Parametric CAD System (build123d) Accepted
018 Documentation & Assembly Guide System (Quarto) Accepted
019 Pitan Extruder Accepted
030 Multi-Format Export System Accepted

ADR Lifecycle

  • Accepted — Decision finalized, implemented
  • Superseded — Replaced by newer ADR, kept for decision history
  • Archived — No longer relevant, kept for historical reference

Creating New ADRs

Use the template at template.md. Number sequentially from the highest existing ADR.