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How to Crimp JST Connectors for 3D Printers

When I first started down the rabbit hole of 3D Printer upgrades, one of my earliest projects was installing a V6 hotend on the Anet A8. It came with a small, 30mm cooling fan and plenty of wiring length was included, but it didn’t have a plug for the board. This conundrum introduced me to the art of crimping my own JST Connectors.

Sure, there were perhaps better options on the table that would cost less upfront. I could just splice the new fan to the original fan’s wiring, or solder the wires to the board, but I prefer to keep my setup clean and professional.

After some Google research, it turned out almost every 3D Printer board uses JST Connectors, the XH series to be exact. Better yet, they are easy enough to make on demand. For a one off weekend project, this probably isn’t worth the expense of parts and tools. But for hobbyists doing frequent upgrades or those running home based printer farms, we can certainly benefit from crimping our own JST connectors as needed.

 

Purchase Parts

720 PCS JST-XHP Connector Kit - $14.99
22 AWG Flexible Wire - $13.99

Tools (Optional)

Wire Stripper Tool - $4.72
SN-01BM Ratchet Crimper Tool - $22.99

 

What are JST Connectors?

JST Connectors (Japanese Solderless Terminal) are an extensive family of electrical connectors, often used in hobbyist and consumer products. There are about 500 different types, and they are found in battery packs, RC electronics and in our case, 3D Printer circuit boards.

 

The most confusing aspect is their naming conventions, which have a range of suffixes like SH, VH and XH just to name a few. Each type has a different shape and spacing between pins, but they are also designed for use with different applications, intended for a specific wiring gauge, current and voltage.

It’s not important for this guide, just something to be aware of. For 3D Printers, we almost exclusively use the JST-XH style connectors with a 2.54mm pin spacing.

JST-XH Connectors

The XH series of JST Connectors are a small, versatile crimp style connector that is rated for use up to 3 Amps on 22 AWG wiring. They are specifically made for wire to board connections, found on our cooling fans, stepper motors, endstops and so on.

This particular type is visually distinguished by (2) arrow looking prongs on the backside, which help secure it when plugged in. That helps maintain a good electrical connection during use, without any concern of loose plugs falling out.

 

Crimping JST Connectors

The process of making JST Connectors can ultimately be broken down in to 3 simple steps… strip, crimp and connect. We prepare the wiring, crimp on a terminal and insert it into the plug.

When using the correct tools, it will take about 30 seconds per wire and most 3D Printer connectors are either 2 or 3 pins. Without the recommended tools, we can still crimp the JST connector terminals in Step 2, but the experience will be a lot less pleasant and far more tedious.

1. Strip the Wire

If you’ve ever worked with wiring before, you’re probably already familiar with how to strip it. For those doing this for the first time, we’ll take a brief look at how to do it.

 

Since our wiring is insulated, we need to strip a bit off the end to expose the metal strands inside. These will be crimped inside of the JST connector, and when plugged in to the board, the metal to metal contact makes an electrical connection, providing power, ground or signal.

Using the wire strippers, insert about 3mm of wire in the teeth marked 22 AWG. Squeeze the handle grips together and then twist back and fourth, which helps cut through the insulation material. Pull back on the wire and this should strip away the coating, leaving you with bare wire strands to use.

2. Crimp Terminals

JST Connectors use a small metal crimp terminal for stranded wire, with 2 sets of wings that wrap around and grip it in place. When you buy a JST Connector Kit, these come as strips, designed to feed in to an industrial machine. For DIY purposes, we will just snap them off and crimp by hand.

When I first started out, I was using needle nose pliers to bend each wing in to place. In theory it’s doable, I even managed to make a few decent ones, but the sheer frustration of trying to fold tiny metal prongs around small AWG wiring left me beyond frustrated. This is one of those situations where it’s absolutely worth it to use the right tool for the job.

 

The SN-01BM Ratcher Crimper does take a few minutes to get the hang of, but it’s dead simple to use and makes the crimping process a breeze. Rather than individually folding the large set of wings around the insulation, and the smaller wings around the wire, it bends both for us in one quick move.

First, we’ll start by placing the metal Crimp Terminal in between the outer most teeth, wings facing upwards. Squeeze the handles together until it clicks in to the first position, which should loosely hold it in place for us.

The IWISS SN-01BM tool has 6 lock settings that click each time it changes position.

 

Before we continue, it’s a good idea to re-position the terminal, where the back (wing side) should sit flush with the tool’s metal teeth. We don’t want to crush the connector’s end, which should be sticking out the other side with a small bit of clearance. Once the terminal is lined up correctly, clamp it down two more notches to hold it.

At this point, we can go ahead and insert the stranded 22 AWG wire in the opening, making sure it’s firmly seated. When you’re satisfied, squeeze the handle grips together until it has fully compressed, then release and pull out the new crimped wire.

 

If everything was done correctly, the larger bottom wings should be wrapped around the insulation and the smaller wings should be folded over the wire. It doesn’t have to be absolutely perfect, but definitely try and get it as close as possible. Worst case, just snip it off and try again!

3. Connect Plugs

With our wiring crimped and ready to use, all we have left to do now is insert it into the JST connector plug.

 

Now, the back of our Crimp Terminal has a flared metal wing sticking out, this is what holds it in the JST Connector housing. The white female connector shell has slot openings on one side, and when inserted, the wing pops through and locks the wire in position.

Make sure to line up that flared wing with the slot, then go ahead and push it inside. As long as the Crimp Connector shape wasn’t damaged in the previous step, it should slide right in and sit securely in place. Gently tug on the wire to check that it’s snug, then repeat the process until your JST Connectors are finished.

 

Adjusting Wire Position

Perhaps you made a JST Connector and put the wires in backwards, or maybe you bought an aftermarket product and the polarity is wrong.

Good news, it only takes a few seconds to swap these around and fix the issue. That flared wing design on the back of the metal Crimp Connectors isn’t a permanent design, it’s just as easy to remove as it was to install.

Using a pen, flat head screw driver or whatever else is laying around, press the wing down in to connector’s slot while gently pulling out on the wire. As soon as the flared bit can clear the plastic housing, it will just slide ride out. This can be done as many times as needed to make sure the wiring matches the board plug.

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