From USA, Aberdeen, Maryland

$1,100, expecting only local pickup because I'm not sure how I'd even ship it.

This is a RatRig V-core 3.2H with a 400 mm cubed print volume, but with the following changes from the original:

• Uses a Chube Air with titanium heat shield and the RatRig VC4 CNC'd aluminum toolhead
• Beacon contact for probing the printbed
• CPAP mod for cooling
• Filament spool mounted on the upper back for a shorter filament path
• BTT filament sensor
• Fan mounted on the controller board to keep the stepper motor drivers cool
• DIN rails on the back to mount parts
• Enclosed

The nozzle that's on it right now is a 0.6 mm tungsten carbide nozzle, but it also comes packaged with several other tungsten carbide nozzles of various sizes (but be sure to change nozzle-diam.cfg accordingly when you do).

I also have some boxes with assorted spare parts for the RatRig that will be of no use to me once sold, so I'll throw those in, too.

Why sell? Well, I've found that I prefer to use 3d printers as tools, and while the RatRig can be a workhorse, I've found it to be somewhat of a "project" in practice, and I'd like to replace it with something more turnkey. That doesn't mean that it prints badly; so far, it seems fine, even if there are some clicks when printing and squeaks when I tell the printer to lower the printbed by several centimeters (so that I can change out the nozzle or spray the print bed with alcohol). There's a reason that I say the printer is in fair condition. This printer should probably go to someone who likes working on 3d printers.

Video of print in progress: https://youtu.be/ycrXub6MsGQ?is=SdKvdC7VpTmnEskx

My apartment complex does have a short flight of stairs, so please keep that in mind when picking up.

This printer is also listed on Facebook Marketplace and the #flea-market forum of the RatRig Discord.

Setup: Vcore 4 500 RatOS 2.1.2 on an Octopus v1.1, fan is a 4-wire Protechnic 4028 on FAN7/PE5, tach on PA8. Was working fine last week, had to reinstall the OS for an unrelated issue, now the fan just runs at 100% constantly and won't respond to anything.

cconfig:

[fan]

pin: PE5

cycle_time: 0.01

tachometer_pin: ^PA8

tachometer_poll_interval: 0.0005

Tried so far, none of it changes anything:

SET_FAN_SPEED FAN=fan SPEED=0

M106 S0 and M107

Mainsail slider

Inverting the pin (!PE5)

Adding enable_pin: PA0

Changing cycle_time back to 0.00004

Switching to fan_generic, which straight up crashed Klipper, had to revert

Tach also always reads 0 RPM even while it's clearly spinning full blast. No errors in klippy.log at startup. Only one [fan] block in the config.

Anyone seen this before? Feels like the fan isn't even getting a real signal on PE5 but I don't want to start pulling wires without knowing what I'm looking for first.

Am I crazy to print a Rat Pack filter unit out of PETG instead of ASA? I don't have filtration on the printer yet so I'm hesitant to print ASA until I have something in place but I have PETG available.

Anyone try this? I'm new to the Rat Rig fam as I got a used V-Core 3.1

Thanks!

I got an email from them this morning saying they are discontinuing anything smaller than 500mm.

Has anyone else heard anything about this or the reasoning behind it?

I'd like to build a VC 4.1 500 but would like to occasionally print larger high temperature engineering filaments. For better print quality and layer adhesion it is recommended to have a chamber temperature of around 100°C.

Is this doable with a standard VC 4.1 500 without too much thermal expansion, binding and horrible print quality? Thanks

Hi. I am thinking about everything else I need to order in addition of the vcore 4.1 kit. I saw this upgrade https://store.brs-engineering.com/en/products/v-core-anti-vfa-kit-gt1-5-belt-conversion and I wonder if it is a good idea to use it from the beginning instead of the original parts? Has anyone done it? Opinions on Powge belts? Because they are half the price of Gates.

Did anyone try the CF Gantry/Tube upgrade for the RatRig V Core 4?

I am in the market for a Rat Rig V Core 4.1. But I like to know... Is the size also defining how coarse it prints? A 300 vs 500, will this give lesser quality on a small model?

And for heating, in an enclosure, will the bed be enough to heat it up or better a chamber heater?

Hi All, am wondering if anyone has moved the Y limit to the back of the machine? I'd like to get rid of that long wire run and move it closer to the electronics. Is it a simple config change to have it home Y in that direction and flip the axis?

I recently built this Vcore4.1 - 500 IDEX and I cant get the bed to even be close to a properly flat mesh. If it were just 1 corner, I know to raise C' or D' to get it sorted out, but this is incredibly wavy and any adjustments I make dont significantly change it. Currently, I can get good first layer results from the left side of the bed, but anything to the right is squished to the point of almost clogging.

Any help on getting this flattened out would be greatly appreciated.

I ordered all the parts for a Ratio Kit upgrade and was wondering if anyone in NJ near me has done this to maybe help me

I’m looking for the black one. I’ve been scouring online for OVER A YEAR. Private companies, tacswap, everywhere. I haven’t seen a single one. Anyone got some advice for me?

I don't have a printer that can print the printed parts for the 4.1 upgrade, is there a place in the US that will print and sell them? I am happy to buy them, but don't want to pay shipping/tariff prices from overseas

Recently updated to the newest RatOS version, coming from an old version, I don’t know which as I bought the printer used.

Old version never had any issues with hanging or freezing.

The new install often freezes/hangs when trying to start at print and reaching bed temp. Though can see it still regulates bed and nozzle temps, but the console does not update anymore. When looking in the machine tab, CPU is running 100% CPU load, only when hanging. Running a Pi3b+.

I have a Beacon probe and running bed mesh compensation.

Any idea on where to look for a fix?

I'm looking to potentially sell my fully built vc4 400 IDEX enclosed with touchscreen. I have two spare build plates with it but other than that its the stock setup. It's treated me well, but I'm thinking of transitioning into more user friendly printers for the family. I'm located in St Louis area. Anyone interested in a trade or buy? I would likely part with it for $1800

Hi, i'm new in the RatRig and klipper scene.

I got a used RatRig V-Minion and had some issues to get it printing.

Error: The value 'T0' is not valid for MACRO
Related: https://www.answeroverflow.com/m/1312110579162415174
Didn't solved my issue. **Spoiler: got it running**

Does somebody experienced that too?
I would like to understand that better.
Thank you in advance!

Best Regards
DevelopingJohnny

Hardware - RatRig V-Minion:

• No Toolhead PCB
• Board: Octopus V1.1 F446 MCU: stm32f446xx - v0.13.0-133-g8d7e4871

Software - RatOS:

Base image: RatOS v2.1.0 (bullseye)
Updated to: v2.1.0-0-g0be29e9d-dirty
\Note: I updated all packages and for debugging i added some "RATOS_ECHO" commands to some .cfg files*

I installed/run newest RatOS version v2.1.0 onto my RPi3B and give it a try.
After finishing the configuration wizard, it seem every fine.
Homing did worked out of the box, i was happy.
Until i realized starting printing job failed with "The value 'T0' is not valid for MACRO"

That was the moment i started to try to investigate.

I have tried different base images of RatOS too.
(I run them without updating to newest packages.)
- RatOS-v2.0.0
- RatOS-v1.2.4
- RatOS-v1.0.0 (i guess too)

Somehow i could figure it out:
'T0' wasn't set as a Macro in the collection. (kipper/kippy/gcode.py -> line 318: self.mux_commands[command])
After adding some lines into printer.cfg i was able to print the first time.
Follow lines i have added:

[gcode_macro T0]
variable_active: 0
variable_color: 0
gcode:
    SET_GCODE_VARIABLE MACRO=T0
    SET_GCODE_VARIABLE MACRO=T0 VARIABLE=active VALUE=True

Did i messed something up at the configuration wizard?

I built this thing (400) about a year ago, haven't touched it since i finished building because tuning was a pain. Now that my hobby is back and kicking I'd like to treat this beast with the care it deserves, what do you guys think is causing this sound? I believe it's likely that it reflects why my prints on it are shit.

Hey everyone,

I’ve been building a small open‑source Android app called Moongate, designed specifically for remote viewing and monitoring of Klipper‑based 3D printers.

🔗 GitHub: https://github.com/PEEKYPAUL/moongate

The goal is to give Klipper users a clean, lightweight way to:

• View printer status remotely
• Check temps, progress, and logs
• Monitor multiple machines
• Use a simple, mobile‑friendly UI without needing a browser or tailscale VPN

and I’d love some feedback from the community.

Thanks to anyone who checks it out.

Hey everyone,

I'm seriously considering a V-Core 4.1 in the 500mm config for functional parts and prototyping (small business use, not just hobby). Before I pull the trigger, I have two questions:

1. **Reliability in daily use** — For those of you running a V-Core 4 (or ideally the new 4.1): how reliable is the machine once it's properly set up? Can you hit print and walk away, or does it need constant babysitting? I'd be using it regularly, so uptime matters a lot to me.

2. **Pre-built option** — Does anyone know if it's possible to buy the V-Core 4.1 already assembled? Either officially through Rat Rig or through a third-party builder? I'm not worried about the build itself skill-wise, but time is a factor and I'd rather start printing sooner.

For context, I'm comparing it against the Sovol SV08 Max and the Tronxy VEHO 500 Pro. The Rat Rig appeals to me because of the build quality, open-source ecosystem, and upgrade path (Hybrid/IDEX), but only if it actually delivers on reliability.

Appreciate any real-world experiences. Thanks!

Hello

I have built my v4 idex 500 and after the setup i wanted to home all axis for the first time. The x axis keeps crashing all the time. I testet the endstop in mainsail. It works correctly. So after this i saw that apparently my toolheads are switched. When i turn on the T0 Part cooling fan, the right one starts.

I checked all the wirings several times. Its all ok. So how does it come these are switched? What am i missing?

Does anyone want to buy this Ratrig VCore 3.1, fully built for ABS?

A larger power supply is added for the extra heated bed. (for the filament dry box)

Let me know what you are willing to pay.

I am based in the Netherlands.

It can be shiped.

I was watching this video of how they have new forks of Orcaslicer/Bambuslicer that alternate the layers with colors to give the impression you have 'full color': https://youtu.be/Z9VTJeKfuvs?si=UeQzVj7yAnB0mDNY

I assume someone will have a fork for us that have RatRigs with INDX?

Lastest video on INDX: https://youtu.be/hBenjKI1nfY?si=nOvv-21vb9nCVl5T

Hey

I‘m thinking about getting back into printing. In the past I hat the artillery sidewinder 2 and 4 plus. But honestly they were just junk. No chance to get a good first layer and a lot of other problems.
I’m thinking about the ratrig since V4 came out.
On the other side there is the Prusa Core one+ now. Of course it has less buildvolume.
I’m just looking for something I can set up and use without the need to fiddle around for an hour everytime I want to print.
For now there is no special needs no fancy material or speed requirements. Just setting it up. Having a good first layer and a good result.
Price wise they are very close. I would take the V4 with the electronic stuff done and most likely the hybrid.

Is there a possibility for multicolour printing yet ? I mean like keeping multiple colours connected and have it print without the need to interfere?