Voron Connector and Wiring Guide — JST, Ferrules, and Terminal Types

Reference Electronics Wiring

Proper connector selection and crimping is essential for reliable Voron electronics. A bad crimp can cause intermittent connections, thermal runaway risks, or complete print failures. This guide covers every connector you will encounter in a Voron build, the right ferrule sizes, proper crimping tools and technique, and common wiring mistakes to avoid. Last updated: May 2025.

Connector Types

Voron printers use several connector families depending on current rating, pin count, and application. Here is a complete breakdown:

JST-XH (2.5mm Pitch)

This is the most common connector on Voron mainboards. JST-XH housings are polarized (keyed) and cannot be inserted backwards. Common pin counts: 2-pin (endstops, thermistors), 3-pin (fans with tachometer), 4-pin (some probe types). Crimp terminals are available for 20-26 AWG wire. Use the genuine JST crimp tool or a high-quality universal crimper for best results.

JST-PH (2.0mm Pitch)

Smaller than XH, used on compact fan connectors and some mini boards. More fragile and harder to crimp by hand. 2-pin is most common for small 4010/4020 fans. The smaller pitch means adjacent pins can short more easily if wires are stripped too long.

Dupont (2.54mm Pitch)

The standard 0.1-inch pitch connector used on Arduino-style headers. Common on endstop switches and some probe connectors. Less secure than JST connectors — they can vibrate loose. For critical connections, prefer JST. For toolhead boards, use Molex Pico-Clasp or JST instead of Dupont.

Molex Micro-Fit 3.0

High-current connector used on the AC bed heater input and power supply connections. 4.2mm pitch Micro-Fit terminals can handle 5A+ per circuit when properly crimped. These require a specific Molex crimp tool for best results. Never use Dupont-style crimpers on Micro-Fit terminals.

SPOX (3.0mm Pitch)

Optional connector type found on BTT Octopus boards as an alternative to screw terminals for fans and heaters. Less common in Voron builds since most builders use screw terminals directly.

Wire Ferrules

Ferrules are crimped onto the stripped end of stranded wire before inserting into screw terminals. They prevent wire strands from splaying, ensure consistent contact, and prevent damage to the terminal block. Never tin wires with solder before inserting into screw terminals — solder creeps under pressure, creating a loose connection that can overheat and fail.

Ferrule Sizes by Wire Gauge

Insulated vs Non-Insulated Ferrules

Insulated ferrules have a color-coded plastic collar that extends past the crimp, providing strain relief and preventing shorts. These are recommended for all Voron wiring as they make the crimp stronger and the connection safer. Non-insulated ferrules are used only in very tight spaces where the plastic collar would not fit.

Standard color coding: 0.5mm (white), 0.75mm (gray), 1.0mm (red), 1.5mm (black), 2.5mm (blue). Always match the ferrule to the actual wire gauge — an undersized ferrule will not crimp properly, and an oversized ferrule will leave gaps.

Crimping Tools

The quality of your crimp tool determines the reliability of your electrical connections. Cheap universal crimpers produce inconsistent results. Recommended tools:

• Engineer PA-09 — The gold standard for JST and Dupont crimps. Precision dies produce consistent, gas-tight connections. Expensive but worth it for a full build.
• IWISS SN-025 — Excellent value for ferrule crimping. Ratcheting mechanism ensures proper crimp pressure. Compatible with insulated ferrules from 0.25mm to 6mm².
• IWISS SN-01BM — Modular crimper with interchangeable dies for JST-XH, JST-PH, Dupont, and Molex terminals. Good all-in-one option.

Do not use the cheapest no-name crimpers from Amazon or AliExpress. They lack proper die alignment and will produce weak crimps that fail under load or vibration.

Ring Terminals

Ring terminals are used for AC ground connections (earth ground). The ring is bolted to the chassis or a dedicated ground stud on the frame. Use properly sized ring terminals for the wire gauge (16 AWG for AC ground) and bolt size (typically M4 or M5). Crimp with a ratcheting terminal crimper — do not solder.

Ferrule Insertion and Stripping Technique

Getting the details right prevents failures:

• Strip length — Strip exactly the length of the ferrule barrel (typically 8-10mm for insulated ferrules). Too short and the ferrule won't grip properly. Too long and bare wire protrudes past the ferrule.
• Insertion depth — Push the stripped wire into the ferrule until it bottoms out against the plastic collar. You should see the wire end at the tip of the ferrule.
• Crimp position — Center the ferrule barrel in the crimper die. For insulated ferrules, the crimp should be on the metal barrel only, not on the plastic collar.
• Pull test — After crimping, give the wire a firm tug. A proper crimp will not budge. If it pulls out, strip and re-crimp with a new ferrule.

Common Wiring Mistakes

Tinning Wires Before Ferrules (BAD)

Solder is soft and creeps under screw terminal pressure. Over time, the connection loosens, causing high resistance and heat buildup. This is a fire risk. Always use ferrules — never tinned wires — in screw terminals.

Over-Crimping

Applying too much pressure can crack the ferrule barrel or cut through the wire strands. Use a ratcheting crimper that stops at the correct pressure. If you hear crunching, you are crushing the wire — cut and re-crimp.

Wrong Ferrule Size

Using a 1.5mm ferrule on 20 AWG wire leaves the wire loose inside the barrel. Using a 0.5mm ferrule on 18 AWG wire will not fit at all. Always match ferrule size to wire gauge exactly.

Not Using Strain Relief

Wires that exit connectors without strain relief will eventually break at the crimp from vibration. Use cable ties and adhesive tie-downs to secure wiring looms.

Quick Reference Card

• Endstops: JST-XH 2-pin or Dupont
• Thermistor: JST-XH 2-pin
• Hotend fan: JST-XH 2-pin (standard) or JST-PH 2-pin (small)
• Part cooling fan: JST-XH 2-pin
• Bed heater: Molex Micro-Fit or screw terminal with ferrule
• Stepper motors: JST-XH 4-pin or Dupont 4-pin
• AC ground: Ring terminal, M4 or M5
• Toolhead board: Molex Pico-Clasp 4-pin or JST-GH