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Panel Mount & Harness Tips

Disclaimer

  • Recommendations are not universal; they are starting points to begin your own efforts.
  • No information here replaces the advice of a professional.
  • Document, label, and test your wiring harnesses!
  • Test your crimps!

Reading Pin Order Entries

Each pin order table has three columns:

  • Name: an abbreviation for what the pin does. This is for identification only.
  • Pin #: order of the pin in the connector.
  • Color: optional color-coding for the conducting wire.
    • Colors do not always match the wire colors that usually tail a component; this is meant to maintain internal consistency.
    • Colors are solely to help visual identification.

Entry Abbreviations

Abbreviations for components have three parts: [Type][Position][#].

For example, in MOTZ2:

  • MOT is motor;
  • Z is the axis; and
  • 2 refers to the second stepper.

Component Names

Abbreviation Component
ABL ABL sensor
BED Heated bed
FAN Fan
FIL Filament runout sensor
HOT Hotend
I2C I2C bus
LIM Limit switch
LGT Light (not RGB)
MOT Stepper motor
PE Protective earth
RGB RGB LEDs
SPI SPI bus
TH Thermistor

Positions: Steppers and Limit Switches

Abbreviation Position
X X axis
Y Y axis
Z Z axis

Positions: Fans, Lights, and Thermistors

Abbreviation Position
H Hotend/toolhead
E Electronics enclosure
C Chamber/printer enclosure

Wire Colors

Six (6) color sets of hookup wire often come with the same color combinations. We use this palette throughout, along with the following abbreviations:

Color Abbreviation
Black K black
Blue B 🔵
Green G 🟢
Red R 🔴
White W white
Yellow Y 🟡

Secondary Colors

Most pin types will have the same wire color: analog signals are yellow, PWM pins are green.

GND and VIN are black and red, respectively. To help balance the lengths of color used in a harness, some pins list a secondary color.

  • 3.3-volt and 5-volt VIN pins have blue as a secondary color where enough colors are available.
  • GND pins that are drains for analog signal pins have white as a secondary color.

Considerations

Wire Gauges

If you do not regularly work with hookup wire, up-gauging to AWG #24 for any smaller gauge is an option to reduce sourcing costs.

Pros & Cons
  • Saves by buying more of one type of wire.
  • Larger wires can be easier to work with.
  • Reduce number of pins types for some connectors (e.g., Molex Mini Fit family)
  • Increases thickness of wire bundle.
  • Can significantly increase weight of toolhead bundle.

Panel Mount Connector Patterns

There are two ways of designing of a wiring panel. This guide starts with a one-to-one pattern, then uses this build larger cable segments in a one-to-many pattern.

One-to-One Panels

Example of a one-to-one panel

Each component of the printer has an individual connector on the panel.

These are point-to-point, single component connectors.

Pros & Cons
  • Simple to design: cables are point-to-point.
  • Cables can be replaced easily.
  • Large number of connectors to connect & disconnect.
  • Messy wire bundles.
  • Significant slack must be left before wrapping bundle.

One-to-Many Panels

Example of a one-to-many panel

Grouping components into one connector greatly reduces the nubmer of cables and simplifies servicing.

A one-to-many panel mount connects multiple components. From the panel, the cable may branch further.

Pros & Cons
  • Easier to mate and disconnect.
  • Cheaper/fewer connectors to source.
  • Compact panels.
  • Tight wiring harnesses.
  • Complex to design and assemble.
  • Unforgiving of mistakes.
  • Difficult or impossible to repair connectors with large numbers of pins.

Further Reading