Rat Rig V-Core 3 Supplement
This page is a guide to building the Rat Rig V-Core 3. Here, you can benefit from everything I learned while building my own Rat Rig V-Core 3.1 standard kit.
General build tools #
These are the hex keys you’ll need:
- For M6 bolts - H5
- For M5 bolts - H4 (5/32" is identical)
- For M3 bolts - H2 (5/64" is identical), H2.5 (3/32" is close, but not ideal)
Wiha makes a nice set of hex keys which contains everything you’ll need.
While not necessary, the greatest quality of life tool for this project is a precision electric screwdriver. I used the high torque setting for all screws that engage with plastics, as well as on all of the linear rails, so that each screw would have a precise and even torque. The linked screwdriver doesn’t include an H4 or H2 bit, which are necessary for the M5 and M3 bolts. This micro hex bit set fills the gaps.
You will have to make various fairly precise measurements. I used a digital caliper and a set of precision steel rulers.
To verify the squareness of the bed, I used a carpenter square, but it was still a very tedious process to get it exact. A long ruler to check the distances across diagonals might have been useful, but I didn’t use one.
In order to do the heat inserts on the toolhead, I used a Hakko FX888D-23BY soldering iron set to 300°F.
I had an issues with both my X/Y pulley grub screws, and my Z-axis grub screws being loose. Make sure to double check all of these before you turn on your machine. It seems like a good idea to use a light threadlocker on them to prevent loosening in the future, but I didn’t, yet.
Mounting hardware #
The standard kit does not include an electronics panel. You’ll need to buy one or get one made. I found that the cost for a panel from local laser cutters exceeded the price at Mandala Rose Works, so I recommend purchasing a 3mm panel with the electronics mounting holes directly from them.
When mounting the panel to the frame, a strong magnet makes it very easy to align the T-nuts under the acrylic.
Power supply & solid state relay #
In order to mount the power supply, you will need 4x M4x6mm screws, which were not included. For the SSR, you’ll need 2x M4x10mm screws, also lacking from the standard kit. When using a 3mm electronics panel, I found that 8mm and 12mm lengths were superior, as they have better engagement. This M4 bolt set contains all 4 lengths that you might need.
Raspberry Pi #
In order to mount the Raspberry Pi, you will need M2.5 standoffs, which were not included. I mounted these M2.5 nylon standoffs to the panel, which made it easy mount the RPi later. This M2.5 brass standoff set is another option, if you prefer metal mounting hardware.
Control board #
Mounting hardware for the control board is included (M3 cap head bolts, nylon spacers, lock nuts), but I opted to use this M3 brass standoff set instead, since the standoffs are easier to work with later on. This M3 nylon standoff set is another option, if you prefer nylon mounting hardware.
Electronics #
AC / mains power #
Rather than wiring a plug directly from the power supply and relay, I used a panel mount C14 plug adapter with a power switch. Not only does it look nicer, since the main wiring will be fixed the the frame, it’s safer. It is important to get a plug rated for the current you’re going to draw. For the 500mm size on 120 volts, you will need a plug rated for 15 amps, like the one I linked. To mount the socket to the frame, I made this model. I didn’t have enough extra M6x12 bolts to mount it, so I had to buy some, but there were plenty of extra 3030 M6 drop in T-Nuts in the standard kit.
If you go this route, you’ll need a C13 power cable rated for 15 amps.
The power supply only handles around 5 amps, so I decided to use a flexible 16 gauge wire for the circuit to the main board, which is more than necessary. This is also the wire I used to power the heater on the toolhead.
I ran a 14 gauge ground wire to the frame and the bed. To attach it to the bed, I used an M5x16 countersunk bolt. To attach it to the frame, I used one of the extra M3 T-Nuts that came with the standard kit, and a couple of washers to get it wide enough for the channel.
I used this tool to strip the wire and attach the wire terminals.
DC / component power #
A cheap set of JST-XH connectors and Dupont connectors will do fine. For tools, use a set of fine wire strippers and a micro terminal crimping tool.
Rather than running 8 components worth of wires from the toolhead to the electronics panel, I purchased a BIGTREETECH EBB42 toolboard, which simplifies it down to two connections: power and USB. Not only does it greatly reduce the complexity of the wiring, but it also makes the cable bundle a lot easier to manage. The toolboard uses JST-PH connectors, but they include all the connectors you’d need in the box. I mounted the toolboard to the toolhead using this bracket.
The 4028 fan runs directly to the control board. You can cut off the existing connector and run the wires you need, or you can make a custom wire using a PicoBlade 530470410 socket which mates with the existing connector. I did this, but it’s probably a bit excessive.
Finally, you’ll need to get a USB-C to USB-A cable to connect the toolboard to the Raspberry Pi. The RatOS documentation specifies a USB 3.1 cable, but that’s not necessary. You just need a durable shielded cable.
Cable management #
For cable management, I used a bunch of 4 inch zip ties and 8 inch zip ties to hold wires together, and Iprinted a bunch of these 3030 channel clips to keep the wires tucked into the frame channels.
For the toolhead loom, I wrapped it with a braided cord protector, then, since I have something overhead, I attached a retractable keychain to the middle of the loom. If you don’t have something overhead, many people recommend using a 1mm spring steel wire to keep the loom suspended.
Software #
When setting up the Raspberry Pi and the control board, you will need two micro SD cards. One will be for RatOS on the RPi, the other is only used briefly to flash the firmware to the control board.
Et cetera #
For the filament guide tube, I purchased 10 feet of 4mm OD, 2mm ID PTFE tubing. The build guide suggested 4mm OD, 2.5mm ID or 3mm ID, but I was not able to find such a thing. Standard filament is 1.75mm OD, so I decided that it was fine. This tubing is a couple of feet longer than the guide requires, so I used the extra for the little friction reduction tubes on the spool holder.
Also, before running the Z-tilt homing function, make sure to get your bed as flat as possible by hand first. If you don’t do this, you risk breaking an opposite corner as the machine tries to probe.
If something is missing, or if you believe any of the information on this site is incorrect send me an email to let me know. I will fix the issue as soon as possible!*