How to Wire and Install Electronics for a Voron 3D Printer – Build Diary Part 6

Welcome to Part 6 of RaveRobot’s Voron 2.4 build diary. In this post we will discuss assembly of the running wiring and connecting the electronics

Intro

With the frame, motion systems, and extruder/hotend all complete the last key bit to getting this printer build finished is of course wiring. I’ll be making my own wiring loom, running the wires through the drag chains, crimping all connectors, installing the electrical components on the underside of the printer. You may have noticed in previous articles that the bed is missing, I’m going to go over installing that here as well, it is heavy and there has been a lot of moving the printer around so I thought best to leave that for last.

Materials and Preparation

For once we don’t have a lot of headset inserts to install but there is going to be a lot of wiring and crimping going on. Exactly what wires and crimps you need is going to depend on what you have decided on for electronics. I’m using dual SKR 1.4 main boards and I’ve opted not to install the Raspberry Pi in the electronics box or use a 5v power supply down there as I’m going to steal the Pi and screen from my Ender 3.

You will want to invest in some wire strippers and a decent crimping tool if you are planning to do all of this by hand. A good soldering iron and a multimeter would also be excellent additions to your tool chest if you do not already have some. There are some vendors who have started selling pre-made wiring looms which, while not cheap, can save you a lot of time if you really don’t like this sort of thing.

One thing that is very important is to make sure you obtain the right wire for this build. Vorons move fast and the wires are all contained in a drag chain. If your wire is not motion rated and the right quality you will have breaks later on and either a fire or a broken printer. Remington sells excellent PTFE insulated wire which is ideal for this application. I’ve opted for all black as it’ll look better in the drag chain (red would also have been very sharp I think) but that means I need to be exceptionally careful with labeling everything as I go so I don’t mess up.

The TMC 2209 stepper drivers for the SKR 1.4 require a pin to be removed as well since I won’t be using sensorless homing and it can cause some issues. To do this I simply heated up the pin with my soldering iron and then once it was hot I pulled it out with a pair of pliers. This step isn’t required for all boards so if you are following along you’ll want to make sure before you start cutting/removing pins from things.

Making the Wiring Loom

In order to make the wiring loom we need to know the length of wire you will need from the underside of the printer up to the A/B motors, up to the X/Y endstop pod, and up to the toolhead. The best way to find this out is to loosely install the drag chains and then pull a single piece of wire to each place and then measure that length. Once you have all your measurements you can safely begin cutting individual lengths of wire and labeling them on both ends.

I found the easiest way to make a loom was to lay out my drag chains on the floor end to end in the orientation they will be in the printer and then after I cut each wire to lay it carefully in the chain and then tape the ends to the floor so they didn’t escape. Once I had all my wires carefully laid out I then gently combed through them to make sure they wouldn’t bind up or have issues and I closed the drag chains.

A serious pro tip here is to run a few spare wires all the way to the hotend and then just leave them in the chains. If you ever have a break or want to add a component (like toolhead lights or additional thermistors) you’ll be ready to go and won’t need to muck around with doing this again. I’m running 4 spare wires as I have a lot of extra and there is room in the chains for this.

Once the loom is done, attach it to the frame/gantry with screws and t-nuts. Check the full range of motion for the gantry and that nothing is interfering, you may need to remove a link or two in the chains. Once that all looks good feed the wiring loom down into the electronics compartment and tape it off to the side. Pull the wires to their locations (AB motors, endstops, hotend) and tape them in place. They should be longer than needed, we’ll cut and crimp them later.

Electronics Compartment

The underside of the printer is where all the electrical components will be housed. There are a few printer parts to assemble down here to mount the power supply, boards, and solid state relay to the DIN rails. These are easy to assemble but as they involve cutting threads into printed plastic with self tapping screws go carefully and if the printed tolerances are not good you might want to loosen up the holes with a drill bit first.

To assemble the plug and power inlet I’m going to use insulated spade terminals and crimp them onto my wires. This is pretty basic, just make sure you have large enough gauge wire to handle the voltage from the mains wiring. Soldering these connections is not ideal, crimping is better. A neat trick is to get some WAGO connectors which let you take one wire and split it to multiple which will make running the wires around down here much simpler.

The wiring diagram provided in the build manual is pretty good so I’m not going to try and re-create it but I’m including images of all the steps in order to help with the basics. You need to take your hot wire (black) and run it from the inlet to a few places. Your switch, 24v power supply, 5v power supply (if using one), solid state relay (SSR) which will power the heated bed. Anywhere you run a hot wire you also need to run a neutral (white) as well. In addition you will be running a ground wire (green) to the power supplies, to the grounding screw on the bed, and a grounding screw on the frame.

Once the power supplies have power it is a good idea to plug in the printer and power them up to make sure everything is working as intended. Doing this before the boards are hooked up allows for you to ensure that if something is wrong you don’t fry more components. Use a multimeter to ensure that the power output is correct and if not you can use an insulated screwdriver to turn the adjustment screw and dial that right in. Once you are happy kill the power and unplug the printer from the wall.

With the main power was done I needed to run my 24v power to my two main boards. Since the power inlet on these boards are screw terminals I crimped on ferrules to the end of my wires to make sure I had a nice strong connection. With my power run to the boards the next step was again to power the printer on and make sure the lights came on and nothing shorted out. With that test done, I again disconnected the printer from the wall and was ready to start hooking up components.

The inductive probe has an additional requirement when it is being wired up which is good to make sure is installed at this stage. The probe requires 24v to operate but if it returns 24v back down the signal to the main board it will likely fry that pin as most are not 24v tolerant. A BAT85 schottky diode is used on the signal line to reduce the voltage and prevent a short. This diode needs to be soldered onto the wire somewhere between the probe and the board and down here in the electronics bay where nothing is moving is a great spot for it. Make sure the orientation is correct (these only work one way) and then heat shrink wrap it afterwards to prevent shorts.

The exact number of connectors and type will vary based on the components used in the printer. Dual SKR 1.4 boards were popular for a while but now Fystech has created the Spider board and BigTreeTech has created the Octopus board. Both have 8 stepper drivers and can run a V2.4 from a single board so that is likely a better option going forward for new builds. For the most part the main board side of the wires will be JST or screw terminal ferrules while the motor/hotend side will be Molex Microfit connectors. If you are using a toolhead PCB in your build then the number of wires and type of connectors will be a bit different so always check before you start cutting and crimping things.

Crimping can be a bit tedious but if you have the right tools and follow a few key rules it isn’t too bad. Strip only enough insulation from the wires to just fit into the pin. Crimp the exposed wires firmly and carefully then crimp the second portion which fixes the insulation in place. Perform a tug test to make sure the crimped pin isn’t going to just immediately fall off. Once that is done for all the wires for that connection insert them into the housing. If you are using all one color wire like I did then you want to use multicolored heat shrink wrap on the wires to make sure you can easily tell them apart within a connection.

Prepping the Heated Bed

The bed of any 3D printer is not somewhere to skimp on quality. The flatness and resistance to warping when heated are going to make the difference between a successful print and a pile of spaghetti. Voron Design suggest a cast aluminum MIC6 blanch ground bed which will be extremely flat and resistant to warping. A silicone bed heater must be affixed to the bottom of the bed. You can drill and counterbore a bed yourself but there are many vendors selling them already done so I opted for a beautiful one from Mandala Roseworks.

It was easy to attach my Kenovo silicone heater with 3M adhesive pre-applied. I cleaned the underside of the bed with IPA and gently scuffed it with steel wool to ensure a better bond. Carefully removing the backing a bit at a time and then pressing it down onto the bed to ensure to air bubbles took some time was was well worth it. Once the heater was attached I weighed it down and let it sit for a few days to allow the adhesive to fully bond. I then used JB weld room temperature vulcanization (RTV) to create a perimeter around the silicone heater to further provide insurance incase the adhesive was to fail.

Some people will apply PEI directly to their bed and print directly on it. I love the utility of removable spring steel sheets so I applied a high temperature magnet to my bed in the same way I did the heater and then used a razor to cut around the edges and then expose the mounting holes. With that done my bed was ready for installation on the printer on top of the M4 knurled nut spacers. I did not fully tighten the screws at this stage as I wanted to tighten them with the bed at its maximum temperature to prevent warping.

Wiring the heated bed is fairly simple with the hot wire from the inlet running into the SSR, out of the SSR and into a thermal fuse, then out and into the heater. The neutral wire runs from the inlet to the other end of the bed heater. The bed thermistor is run directly to the main board. The thermal fuse must be attached directly to the underside of the bed with a screw (or JB weld) and then a ground should also be run from the power inlet to the underside of the bed and secured in place with a screw. I used a set of WAGO connectors here behind the bed to handle all these connections which will make it easy to remove the bed if that is ever required.

Behind the bed the Z-endstop must be installed. This is a simple part with a microswitch in a housing and a metal pin above. When homing the V2.4 will tap the pin with the nozzle which will then press the switch. A pulley is sacrificed to make this part and once final assembly and testing is complete a notch should be cut in the pin and a grub screw used to prevent it from accidentally being removed. There is a popular user mod as well called the Sexbolt which replaces this and does not need any notches cut or pulleys deflanged.

With all my wiring and electronics done the printer is physically finished. The next steps are to hook up the Raspberry Pi, flash the firmware, configure Klipper, and then run my pre-flight checks. I can almost smell the melting plastic now.

Voron Build Diary Guide

• 1 – Sourcing Your Parts
• 2 – Building the Frame
• 3 – Assembling the Z-Motion System
• 4 – Assembly and Installation of the X/Y Gantry
• 5 – The Afterburner Direct Drive Extruder
• 6 – Wiring and Electronics
• 7 – Klipper Firmware Installation and Test Flight
• 8 – Printer Tuning and Finishing Touches (Coming Soon)