Voron Silicone Wire Crimping Guide — Complete Step-by-Step

Build Beginner Wiring Electronics

Crimping is the single most important wiring skill for building and maintaining a Voron. Every connector in a Voron — from the toolhead JST headers to the mainboard power terminals, endstop switches, and fan connectors — uses crimped pins. A bad crimp causes intermittent connections, voltage drop, overheating at the connector, and the infuriating "thermal runaway" errors that make you replace a perfectly good thermistor. This guide covers everything: the connectors used in Voron builds, the right crimp tools (including budget China-direct options), the technique for crimping silicone wire, how to avoid the most common mistakes, and proper connector assembly. Last updated: May 2025.

Difficulty Level

Beginner to Intermediate. Crimping itself is not hard — inserting the pin correctly and applying the right pressure takes practice. Expect to ruin 5-10 crimps before you get consistently good ones. Budget $50-80 for a decent crimping setup (tool + connectors + practice wire). Once you learn, each crimp takes 30-60 seconds.

Why Silicone Wire Is Different

Silicone wire is the standard for Voron builds because it stays flexible at enclosure temperatures (up to 200°C rated) and resists the brittleness that PVC wire develops in hot environments. However, silicone wire is more difficult to crimp than PVC wire for one reason: silicone insulation compresses instead of cutting cleanly.

When you strip silicone wire, the insulation tends to compress around the strands instead of cutting cleanly, leaving a ragged edge. When you crimp, the silicone can get caught in the crimp barrel, creating a poor connection that looks good but fails after a few thermal cycles. The fix: use a sharp, high-quality wire stripper with a depth stop, and strip at least 3mm of insulation to ensure the wire strands fully enter the crimp barrel.

Connectors Used in Voron Builds

Tools Needed

• Wire strippers: Automatic or manual with depth stop. The Knipex 12 52 180 (automatic) or Engineer PA-09 (manual with precision depth stop) are the community favorites. Budget China-direct alternatives: the IWISS HS-308 or SN-028 are acceptable for $8-15.
• Crimp tool: The IWISS SN-254 or SN-28B are the standard for JST-XH and Dupont connectors. For Molex Micro-Fit 3.0, you need a specific tool (IWISS IWS-3220M or equivalent). The Engineer PA-21 or PA-09 crimpers are high-end options that work well with silicone wire. Budget: the generic "22-18 AWG crimp tool" for $8-12 can work with practice.
• Flush cutters: For trimming wire to length. Must be sharp to cut silicone cleanly without crushing.
• Magnifying lamp or headset: You need to inspect crimps closely. Silicone wire strands are thin (0.08mm each for 24 AWG) and a bad crimp is easy to miss without magnification.
• Multimeter: For continuity testing of each crimp.
• Tweezers (fine-tip): For handling pins and inserting them into housings.
• JST connector kit: Assorted JST-XH and JST-PH housings (2-pin, 3-pin, 4-pin) and matching pin contacts. Buy 100+ of each pin type — they're cheap and you'll use them.
• Practice wire: A 1m length of 22 AWG silicone wire in a bright color (so you can see the strands clearly).

Step-by-Step Crimping Procedure

Step 1: Prepare the Wire

1. Cut the wire to length with flush cutters. A single clean cut is better than multiple snips.
2. Strip 3.0-3.5mm of insulation from the end. For JST-XH pins, this is the correct insertion depth. For JST-PH, strip 2.5-3.0mm. Too short: the wire won't reach the barrel, creating a weak crimp. Too long: bare wire exposes past the barrel, creating a short circuit risk.
3. Inspect the stripped end. The strands should be perfectly circular, un-nicked (no cut strands), and free of insulation residue. Twist the strands gently to align them. Do not tin the wire with solder — solder creates a brittle joint that cracks under vibration and makes the wire too large for the crimp barrel.

Silicone wire trick: Use a lighter to quickly pass the stripped end through a flame (1/2 second). This shrinks any silicone insulation whiskers that didn't cut cleanly. Let it cool for 2 seconds before crimping. Do not overheat — the silicone will melt and drip.

Step 2: Position the Pin in the Crimp Tool

Hold the pin (JST-XH BXH-001T-P0.6, for example) with the wings facing up. The crimp barrel has two sections: the wire barrel (larger, crimps onto the insulation) and the conductor barrel (smaller, crimps onto the exposed wire strands). The pin must be oriented so the conductor barrel is closer to the tool handle.

1. Insert the pin into the correct die position on your crimp tool. For the SN-28B: the JST-XH pin goes in the #1 position (smallest die). For the SN-254: position A or 1.
2. The pin should sit flat in the die, with the wings pointing up and the pin tip pointing away from you. Close the crimp tool handles slightly to hold the pin in place.
3. Verify that the conductor barrel is centered over the die opening. If it's off-center, the crimp will be lopsided and the wire won't be held properly.

Step 3: Insert the Wire

1. With the pin held in the tool, insert the stripped wire into the conductor barrel. The wire insulation should just reach the insulation barrel — you should be able to see the wire strands through the conductor barrel.
2. The wire strands must be flush with the end of the conductor barrel or slightly protruding (0.2-0.5mm past the barrel). Do not insert so far that wire enters the pin mating area.
3. The insulation must fully enter the insulation barrel. If there's a gap between the insulation and the barrel, the crimp won't have strain relief and the wire will break at the crimp point.
4. Hold the wire steady. Do not pull or push while crimping.

Step 4: Crimp

1. Squeeze the handles firmly and all the way until the ratchet releases (if your tool has a ratchet). For non-ratchet tools, squeeze until you feel the barrels fully close. The sequence is important: the conductor barrel closes first, then the insulation barrel.
2. Release the handles and remove the crimped wire and pin. Inspect the crimp immediately.
3. Good crimp check: (1) The conductor barrel should be folded tightly around the wire strands — no gaps, no strand splaying. (2) The insulation barrel should grip the insulation firmly — not crushing it (which cuts the silicone) and not loose (which eliminates strain relief). (3) The pin should be straight, not twisted or bent. (4) There should be no wire strands visible outside the barrel except the very end.
4. Pull test: give the wire a gentle tug (1-2 lbs force). If the wire pulls out of the barrel, the crimp is bad — cut and re-crimp.
5. Continuity test: use a multimeter to confirm electrical connection between the pin contact tip and the wire end.

Step 5: Insert the Pin into the Housing

1. Orient the pin correctly. JST housings have a locking tab inside. The pin has a matching barb that clicks into place. Look at the housing from the front (the side where the mating connector inserts) — you should see a small rectangular hole. The pin barb must align with this hole.
2. Insert the pin into the rear of the housing (the side with the wire entry openings). Push firmly until you feel the barb click. There should be a satisfying click and the pin should be locked in place.
3. Give a gentle pull on the wire to confirm the pin is locked. If it slides out, the barb didn't engage — you may have pushed it in upside down or the barb was crushed during crimping.
4. Repeat for all pins. Insert them in the correct order — check your board's pinout diagram. Marking the first wire with tape helps prevent ordering mistakes.

Step 6: Final Inspection and Testing

1. Check continuity from the board-side pin to the wire end. All pins should show low resistance (less than 1 ohm).
2. Check for shorts between adjacent pins. Use the multimeter on continuity mode between each pair of pins. There should be no connection (infinite resistance).
3. Check that the connector mates correctly with its counterpart. It should insert smoothly with a positive click when fully seated. If it requires force, a pin may be bent or misaligned.
4. Perform a light pull test on each wire: 0.5-1 lb of force should not dislodge any pin.

Crimp Tool Comparison

Recommendation: Start with the IWISS SN-28B ($15-25 on AliExpress). It covers 90% of Voron connectors (JST-XH, Dupont) and produces consistent results. Add the SN-254 later if you need JST-PH or Molex. The Engineer PA-09 is the best manual tool but costs more and has a steeper learning curve.

Common Crimping Mistakes and How to Avoid Them

Mistake 1: Stripping Too Much Insulation

If more than 1mm of bare wire protrudes past the conductor barrel, it can short against adjacent pins or the connector housing. The solution: measure your strip length carefully. For JST-XH, strip exactly 3.0mm. Mark your wire stripper with a Sharpie at the correct depth setting.

Mistake 2: Not Enough Strands in the Barrel

If the wire has stray strands that didn't enter the barrel, the crimp has reduced current capacity and is mechanically weak. The fix: twist the strands before insertion, and cut off any strands that don't enter the barrel. If 2+ strands missed the barrel, strip and re-crimp.

Mistake 3: Over-crimping (Crushing the Barrel)

If the barrel is crushed flat, it weakens the metal and creates stress risers that crack under vibration. For silicone wire, over-crimping is especially bad because the soft silicone insulation compresses more than intended. Use a tool with a depth stop or ratchet to ensure consistent crimp pressure.

Mistake 4: Under-crimping (Loose Barrel)

A loose barrel means the wire can pull out. This is the most common failure mode for budget crimp tools. Test every crimp with a gentle tug. If it slides out, re-crimp with more pressure or use a different die position.

Mistake 5: Crimping the Insulation Barrel Too Tight

The insulation barrel should grip firmly but not cut into the silicone. A visible ring of compressed silicone is okay. If the insulation is bulging out the sides of the barrel, you've over-tightened and compromised the strain relief.

Mistake 6: Wrong Pin for the Connector

JST-XH and JST-PH pins look similar but have different widths. A JST-XH pin forced into a JST-PH housing won't lock and may fall out during assembly. Always confirm the pin part number matches the housing.

Mistake 7: Soldering the Wire Before Crimping

Tinned wire (wire that has been pre-soldered) is rigid and creates a stress point right at the crimp barrel. Under vibration (which happens constantly in a 3D printer), the wire breaks at the solder joint. Never tin wire before crimping. The crimp barrel makes the electrical connection — solder is unnecessary and harmful.

Ferrule Crimping for Screw Terminals

For connections to screw terminals (power supply, SSR, mainboard power input), use wire ferrules instead of bare stranded wire. Ferrules prevent the wire strands from fraying and ensure the screw terminal clamps evenly.

1. Select the correct ferrule size: black (24 AWG), gray (22 AWG), blue (20 AWG), white (18 AWG), red (16 AWG), yellow (14 AWG), or green (12 AWG).
2. Strip 8-10mm of insulation (ferrules require more stripped length than JST pins).
3. Insert the wire into the ferrule. The wire strands should be fully inside the metal tube, with 0.5-1.0mm of the tube visible before the insulation starts.
4. Crimp with a ferrule-specific crimp tool. The tool has multiple die sizes matching the ferrule colors. Squeeze until the ratchet releases.
5. Insert the ferrule into the screw terminal and tighten the screw. The ferrule should be fully seated in the terminal, with no bare metal visible.

Cost Breakdown (China-Direct Pricing)

China-Direct Sourcing Tips

• Buy the real IWISS, not the clone: There are many "SN-28B style" tools that look identical but use inferior steel. Pay the extra $5 for an authentic IWISS (the tool has "IWISS" laser-etched on the handle). The clones have loose tolerances that produce inconsistent crimps.
• Connector kits are incredibly cheap: A 50-pair JST-XH kit with 100 pins costs $5-8. Buy two kits — one for 2-pin connectors (fans, endstops) and one for 3-pin (thermistors, steppers). The wire gauge in the kit (22 AWG) is fine for most Voron signal connections.
• Buy extra pins separately: You will ruin pins during practice. Buy a bag of 200+ pins for $3-5. Running out of pins mid-build is frustrating.
• Silicone wire quality varies: Good silicone wire has a high strand count (60+ strands for 20 AWG) and flexible insulation that doesn't crack when bent. Poor quality wire has 30 strands and stiff insulation. Look for "ultra-flexible" or "high-strand count" in the listing. UL1007 or UL1015 rated wire is preferred.
• Beware of "Voron wiring kits" that include pre-crimped wires. While convenient, the crimp quality is often poor and the wire lengths may not fit your specific build. Learning to crimp is a better investment.

Troubleshooting

Pin Won't Insert into Housing

The pin barb may have been crushed during crimping. Check the barb — it should spring up and down freely. If it's stuck flat against the pin body, gently pry it up with a fine pick. If the barb is broken, re-crimp with a new pin. Also verify you're using the correct housing for the pin (JST-XH pin won't fit into a JST-PH housing).

Pin Falls Out of Housing

The barb didn't engage. Cause: the pin was not inserted far enough, the barb is damaged, or the housing's locking tab is broken. Inspect with a magnifying glass. If the housing tab is broken, discard the housing — there's no reliable fix. If the barb is okay, try pushing the pin in further with more force.

Intermittent Connection (Works Sometimes, Fails at Others)

This is the classic symptom of a cold crimp — the barrel looks crushed but didn't actually make good contact with the wire strands. Cut the connector off, strip fresh wire, and re-crimp with more pressure. Check that the wire fully entered the conductor barrel last time.

Connector Feels Loose When Mated

The pin may not be fully seated in the housing, creating a gap. Push all pins firmly into the housing until each one clicks. If still loose, the housing's retention force may be worn — replace the housing.

Part Numbers and Specifications

• JST-XH pin: BXH-001T-P0.6. For 20-24 AWG wire. Mating housing: XHP-2 (2-pin), XHP-3 (3-pin), XHP-4 (4-pin).
• JST-PH pin: BPH-001T-P0.5. For 22-26 AWG wire. Mating housing: PHR-2 (2-pin), PHR-3 (3-pin), PHR-4 (4-pin).
• Molex Micro-Fit 3.0 pin: 43030-0001 (female) / 43031-0001 (male). For 16-22 AWG wire. Mating housing: 43645-0200 (2-pin), 43645-0300 (3-pin).
• Ferrule sizes: 24 AWG = black, 22 AWG = gray, 20 AWG = blue, 18 AWG = white, 16 AWG = red, 14 AWG = yellow, 12 AWG = green.
• Recommended silicone wire: 20 AWG for power/signal, 22 AWG for signals, 24 AWG for thermistors. Strand count: 30+ for 24 AWG, 60+ for 20 AWG. UL1007-rated.

Need crimping supplies for your Voron build? We stock factory-direct IWISS crimp tools (SN-28B and SN-254), JST connector kits (XH and PH) with 200+ pins per set, high-strand-count silicone wire in all gauges, ferrule kits, and pre-crimped jumper wires for common Voron connections. Everything you need to wire your Voron correctly.