✅ Piece of paper

✅ Filament

✅ Patience

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Firmware

RatOS is a preconfigured Raspberry Pi image that aims to make it as painless as possible to get Klipper, Moonraker, Mainsail and KlipperScreen up and running on your printer, via an easy to use, modular configuration. It is developed and maintained by Mikkel Schmidt (miklschmidt#2036 on the Rat Rig Unofficial Discord).

Attention, the V-Core 4 is only compatible with RatOS 2.1 - download here

Pay careful attention to all the sanity checks present on the RatOS installation and initial configuration Guides.

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Slicer

Obtaining a Slicer

There are many Slicers free to download, RatRig recommends that you use one of these three, as they have the biggest communities.

Recommended - Prusa Slicer is a free and open-source project. It can be obtained here.

SuperSlicer is a free and open-source project. It can be obtained directly from their GitHub repository.

OrcaSlicer is a free and open-source project. It can be obtained directly from their GitHub repository.

A Slicer takes 3D models (STL, OBJ, 3MF) and converts them into G-code instructions for 3D printers.

All Rat Rig profiles available on these slicers are meant to help you get printing as fast as possible, they are not fully tuned profiles to extract the full potential of the V-Core 4, they are a solid platform to build upon!

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Slicer configuration

Simply choose the appropriate V-Core 4 profile for your machine variant and size. In Prusa Slicer the V-Core 4 is under "other vendors" > "RatRig", In SuperSlicer and OrcaSlicer is under "RatRig".

You can also add filament profiles, RatRig has included pre-tuned Punkfil profiles! Even if you are not using our filament, we recommend using the profiles for the same types of materials, as many factors like cooling, extrusion multiplier, and pressure advance are pre-tuned for you, they won't work as well for different brands but it's a solid starting ground:

Add your machine (Optional)

You can connect your machine directly to the slicer, allowing for a smoother workflow by sending the print job directly from the slicer software.

1) Select your machine and click on the gear next to it.

2) Click "add physical printer"

3) Define a machine name

4) Select "Klipper (via moonraker)" and insert your machine url, created during the RatOS configuration.

5) Click "Test" to ensure your machine is connected to the Slicer, you should see a "Sucess!" window, otherwise check if your machine is connected to the same wifi network as your computer.

6) Click "OK".
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Initial calibration

In this chapter, we will prepare the V-Core 4 for printing. Before the machine melts any filament, there are specific steps that must be followed. If these steps are not followed, different kinds of problems will appear and troubleshooting will be more challenging. It’s like driving a supercar on ice, you might think the problem is the car but in reality the road is in no condition for racing.

Build plate preparation

Before we start tuning the machine, please perform a bed mesh to ensure your build plate is ready to print.

Note: The bed heater should not have been installed prior to this chapter.

Step 1 - Build plate preparation

It's normal to have the bed tilted after assembly. Insert "M84" on the Console, this will disable the stepper motors.

Proceed to manually adjust each lead screw to get the bed roughly levelled, it doesn't need to be perfect, the machine will perfect it later.

Move the toolhead to each Z position and adjust up or down as required.

Step 2 - Build plate preparation

After ensuring the bed it mostly leveled, run the following command:

BEACON_INITIAL_CALIBRATION

The machine will home all axis and prepare the beacon.

It will home your printer and run the calibration fully automated. This command can throw a tolerance error, in this case just repeat it until the command gets successfully completed.

For safety and peace of mind, the LED will turn on as soon as the contact system determines it has a strong enough signal for detection. It should normally turn on up to 10mm in advance of the metal target, allowing enough time to manually estop the machine if necessary.

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Step 3 - Build plate preparation

Once you are happy with the achieved resistance, click ACCEPT on the console then type:

SAVE_CONFIG

‍ Klipper will restart with the new value as default.

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Step 4 - Build plate preparation

Now you may perform a Z-Tilt calibration, this can be found on the dashboard page.

Proceede by clicking on the home icon inside the "HeightMap" tab. Once the printer has homed, click calibration and provide a name for this mesh as shown. RatOS will then create an initial bed mesh.

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Step 5 - Build plate preparation

Inspect your mesh, to get a realistic analysis please check the “scale gradient” and slide the “scale Z-max” all the way to the right. If your mesh looks flat like the image below, you may skip to Step 5.

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Step 6 - Build plate preparation

If your bed mesh is not flat, and appears tilted or twisted (similar to the image below), you will need to verify the alignment and squareness of your frame. You can check the following tutorial video on how to properly identify squareness issues in your frame, from your heightmap mesh image, and how to correct them:

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The image below illustrates a bed mesh with a twist. Twisted meshes are a symptom of a non-squared frame. You will observe a peak or a depression on point C or D,

The blue arrow points to the peak in height. To correct this we need to adjust point C, just unscrew the highlighted quick connectors and gently tap the extrusion on the bottom, re-tighten the quick connectors and perform another bed mesh to verify if the peak is gone. If instead of a peak your mesh has a depression, just push the extrusion downwards. Execute very small adjustments for each iteration until the bed mesh is flat.

Generate another mesh to ensure frame alignment is 100% square, then you can proceed to the next step. If not, take your time and analyse your frame carefully before moving onto the next step.

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Step 7 - Build plate preparation

Unplug your machine from the electricity, turn the power off!

Apply the heater pad. Take your time when performing this step as the heater pad cannot be removed or repositioned. Once any part of the heater pad is placed, do not try to move or remove it under any circumstances. Peel back roughly one inch of the protective sheet along a single side of the heater pad. Position the heater pad centrally on the bottom of the aluminium bed and press down, adhering the edge of the heater to the bed. Working gradually, peel the protective sheet, and adhere the rest of the heater to the aluminium bed. Use a flat plastic tool (like an old credit card) to ensure the heater is fully adhered and that there are no trapped air bubbles.

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Step 8 - Build plate preparation

Using the same method, apply the magnetic surface to the top surface of the bed and install it on the V-Core 4.

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Step 9 - Install the print surface

The flexplate surface may retain impurities from manufacturing, shipping or handling, so washing it with warm water and soap is recommended before the first use. Make sure you dry it with a microfiber cloth to avoid leaving residues of whatever material you may use to dry it, regular kitchen cloths or even paper towels are not recommended.

A dirty build plate will lead to adhesion issues that might be confused with first layer squish/ Z offset calibration problems. The included textured PEI Flexplate doesn't require any type of adhesive, it’s a ready-to-print surface on its own. Regularly wipe your PEI surface down with 70-91% isopropyl alcohol to ensure any grease, or other residues, that may have accumulated on it are removed. This will help increase your surface adhesion greatly.

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Bed wiring

Step 1 -Bed wiring

After placing the bed assembly on the Z arms again, wire the bed wires as the following image shows:

Insert the bed wires through the colar on the electronics panel.

Route the bed thermistor cable as shown.

Step 2 - Bed wiring

Complete the wiring connections for the bed heater, follow here.

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Step 3 - Bed wiring

Close the electronics enclosure using 4 M3x6mm Countersink Screws.

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PID tune

PID stands for proportional integral derivative and it aims at making the heating process more efficient and consistent. Efficiency is important during heating to consume less energy, consistency is key for print quality. A badly tuned heating process looks like the graph below, where the controller can’t stabilise the temperature properly.

In the following video, Stephan from CNC Kitchen explains how a poorly tuned PID affects print quality and how someone might misinterpret the artefacts with other assembly problems.

PID tuning will sequentially power the heater on and off to understand its thermal behaviour, it’s recommended to perform a PID tune for the temperature which you will print at the most.

This calibration must be done for the hotend heater and the bed heater. The temperature parameter should be set to the temperature you expect to print at. If you mainly print PLA, use 210ºC. If you use PETG, 240ºC or 260ºC for ASA/ABS If you print everything from PLA to ABS regularly, pick a happy midpoint like 235ºC (Hotend). Regarding the Bed temperature, it can range from 60ºC (PLA), 85ºC (PETG) and 110ºC(ASA/ABS), a happy midpoint would be 90ºC (BED).

The part cooling fan should be turned on during this calibration as PID tuning must be performed in conditions as similar to a print as possible.

Step 1 - PID tune

To tune PID parameters, you can click on the red highlighted button to use the RatOS default values (220ºC for the Hot end and 80ºC for the bed) or click on the orange highlighted arrow, this way you can choose a temperature value instead of using the RatOS defaults.

Step 2 - PID tune

Once the calibration is finished, type:

SAVE_CONFIG

‍Klipper will restart itself with the new PID values saved to the configuration.

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Step 3 - PID tune

Repeat Step 1 and 2 for the Bed heater.

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Z-Offset Beacon

Ratos comes with a fully automated beacon model and temperature offset calibration. For further information click here.

Step 1 - Z-Offset Beacon

⚠️The extruder and hot end must be clear of filament. Make sure to remove the filament; otherwise, the machine won't be able to accurately perform this calibration.⚠️

Run the following command:

BEACON_RATOS_CALIBRATE

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Step 2 - Z-Offset Beacon

Download the firstlayer_test.stl and open it in the slicer. Make sure the V-Core 4 (size) profile is selected a swell as a filament profile that matches your material of choice. Select a print profile, we recoment starting with the standard Quality, click "Slice now". This step is the same for SuperSlicer and Orca Slicer, although Orca has a different interface.

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Save the modified profile and export the g-code, then upload it to the RatOS interface by dragging it. OR click "G->" to directly send a print from your slicer.

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Load your printer with filament!

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Step 3 - Z-Offset Beacon

Print the test file, while the machine is performing the first layer you can adjust the Z-offset until the first layer squish is on point. It’s important to use small movements to avoid collision, otherwise you will damage your printer. Use the pictures below as a reference.

During the print, once you are happy with the squish, run:

SAVE_Z_OFFSET

⚠️It's important to run the command during the print, otherwise it won't work!⚠️

⚠️It's important to move the nozzle down slowly in small increments to avoid damaging any components.⚠️

Belt Tension

The belt tension graphs are meant to help you troubleshoot your machine assembly, do not look at it as a tunning tool, it's very easy to over-obsess with them. It's impossible to cover every scenario and diagnose every belt graph artefact, this is a very complex and sensitive subject, about which we are still exploring and learning, please feel free to submit your feedback in our Discord community.

Also checkk out the amazing work by the klippain shaketune team here!

Ensure your machine build is finished, all the wirings are clean and there are no loose parts, the machine must be placed on a sturdy surface and there is nothing on top or against the machine. Don't touch the machine during vibration analysis.

It's important to clarify this procedure focused on relative belt tension, meaning it will show you if both belts have the same tension. This is crucial for a smooth motion system.

Ideally, the belt graph for a V-Core 4 would have smooth lines with 2 peaks, as shown below:

Step 1 - Belt tension

To perform a belt tensions graph, just click on the designated button.

Step 2 - Belt tension

You must now analyse your graph and identify potential issues. This is a very complex and involved process, but here are a few generic most found issues.

1) The two peaks (blue and orange) must be aligned on the same frequency, if they are not vertically aligned, then you need to tension or loosen the belts, and your gantry is most likely twisted. Refer to this guide to help you troubleshoot

2)Toolhead vibrations generally cause vibrations on the lines around 100-150 Hz. This can be caused by loose screws, damaged printed parts, loose wires, lack of zip ties to properly constrain the wires, etc...

3) There is an issue with the belt path- If your graph lacks one or two peaks. this most likely indicates your belts are rubbing against something somewhere on their path, this can be an Idler, Motor pulley, frame, etc...

Only one belt path is having issues on this example:

Both belts path have issues in this example:

4) Lastly, it's important to differentiate between vibrations and swinging.

Vibrations manifest in zig zag alike lines and are mostly caused by loose screws on the toolhead or the gantry. Loose idler stacks or missing shims can cause the same effect. try to locate them and fix the issue.

Swinging does show as smooth curves. Many times it's coming from the fact that the printer sits on a shaky table or an uneven floor. Make sure your printer can't shake.

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Hybrid Belts

Tuning all belts from the ground up is a nearly impossible job, so Rat Rig recommends that you first tune your CoreXY belts and only then proceed to add and tune the Y belts.

The Y belts must be tuned recurring to the Input shaper graphs, slowly tensioning them equally. Starting with a low tension is important to understand that the hybrid core-xy input shaper is much more sensitive than a normal corexy setup, a very small increase of the y tension can change a perfect input shaper to the worst one you have ever seen.

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Step 1 - Hybrid Belts

Follow the dedicated guide one Dozuki, explaining you how to route the Y belts, Click Here.

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Step 2 - Hybrid Belts

Tension your Y belts, It's important to tension both belts with the same force, try to rotate both tensioner screws by the same amount. It's easy to ensure you tension both belts by the same amount by verifying if the gantry is straight, the CoreXY gantry alignment guide can be used here, but only regulate the top Y tensioners to align the gantry. start with a low tension and run an input shaper graph.

You should be looking at achieving a clean input shaper graph.

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Step 3 - Hybrid Belts

Gradually increase or decrease the Y belt tension by the same amount, try 1/4 to 1/2 turn increments in the tensioner screw and repeat Step 2. This is a trial and error process so take your time and don't obsess over it, enjoy the incredible BRRR sound the machine provides.

Input shaper (IS)

This calibration follows the Klipper documentation steps but they are simplified for the V-Core 4.

When printing at high speeds and high accelerations parts may start to show surface artifacts most commonly known as ringing or ghosting:

Ringing is caused by mechanical vibrations in the printer due to quick changes in the printing direction. Note that ringing usually has mechanical origins: insufficiently rigid printer frame, non-tight or too springy belts, alignment issues of mechanical parts, heavy moving mass, etc. Those should be checked and fixed first, if possible as described in the Klipper documentation. This makes it mandatory to ensure the mechanical assembly is rigid and smooth before this calibration. The input shaping algorithm is an open-loop control technique that cancels printer vibration by creating an opposite signal. There are two ways of calibrating this feature: automatically with an ADXL345 sensor or manually, the first method is the easiest and most effective although very good results can be achieved manually.

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The V-Core 4 toolhead has the ADXL accelerometer on the EBB42 toolboard:

Step 1 - Automatic IS

Insert:

MEASURE_AXES_NOISE

in the console, if all values are below 100, you are good to go, if your values are above 100 or an error pops up, please check your toolboard and wiring connections.

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Step 2 -Automatic IS

Click on the Macro button or type:

GENERATE_SHAPER_GRAPHS

In the console and the printer will start moving the gantry in X and Y to determine the ringing frequencies. After this, the input shaper graphs will be available under the “machine” tab, inside the “input_shaper” folder.  

In this video: https://www.youtube.com/watch?v=M-yc_XM8sP4, Marc explains how to analyse the generated graphs. The basic information we need to extract from it is the frequency under the MZV protocol, in this case it’s 46.4Hz.

MZV (46.4 Hz, vibr:0.0%, sm~=0.09, accel<=6300)

Notice that this protocol recommends a max acceleration of 6300 mm/s². You will need to compare this value with the one provided on the X graph and choose the lowest value, this value should be used as your external perimeter acceleration inside the slicer profile, to avoid having any visible ghosting. The external perimeter speed and acceleration on the V-Core 4 profiles are somewhat conservative, you can increase them based on your input shaper results to achieve the maximum quality VS performance.

Do the same for the X graph. 

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Step 3 - Automatic IS

Inside the “printer.cfg” go to “user overrides” and paste the following lines:

⚠️Replace the BOLD text with your values.⚠️

[input_shaper]

shaper_freq_x: Your_X_Frequency‍

shaper_type_x: mzv

shaper_freq_y: Your_Y_Frequency‍

shaper_type_y: mzv

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Step 4 - Automatic IS

Click “Save and Exit”.

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Skew Calibration

Skew correction is meant to compensate for a 3D printer assembly which is not perfectly square, the software makes small changes to the toolhead movement, maintaining a perfectly square trajectory. Every detail during the frame assembly may cause a slightly twisted frame, even the screws tightness. Making sure the machine is as square as one can get by hand is very important before advancing to software skew calibration. 

The V-Core 4 has a 3-point kinematic bed levelling system that helps to mask XZ and YZ skew problems. If the build was successful and all Z rails are properly aligned, the Z squareness shouldn’t be a problem, otherwise, a skew calibration should be done for all planes. In this guide we’ll only focus on the XY plane, the procedure is the same for the other axis, more information here.

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Step 1 - Skew

Start by downloading the Skew_correction_tool.stl.

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🛈 When slicing the model, make sure the A corner is pointing to the origin of the plane.

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Step 2 - Skew

Guarantee that no skew correction is running on your machine, check that variable_skew_profile is commented out in the macro configuration section. or type the command below in the terminal. For more information, click here.‍

SET_SKEW CLEAR=1

The [skew_correcton] module requires 3 measurements; the length from Corner A to Corner C, the length from Corner B to Corner D, and the length from Corner A to Corner D.

Let's take the following measurements as an example:

AC= 141.15mm

BD= 140.9mm

AD= 99.65mm

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Step 3 - Skew

Go into the printer.cfg and add the following lines:

[gcode_macro RatOS]

followed by:

variable_skew_profile: "my_skew"

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Step 4 - Skew

Click “save and restart”, then paste into the console

⚠️Replace the BOLD text with your values.⚠️

SET_SKEW XY=AC,BD,AD  

With the previous example, we have:

SET_SKEW XY=141.15,140.9,99.65

Followed by:

‍SKEW_PROFILE SAVE="my_skew"

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Step 5 - Skew

Type:

‍SAVE_CONFIG

and re-print the test, make sure AC=BD. If not, double check all measurements and start this calibration again.

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Let’s get printing

After finishing this guide you may print a benchy to see how your machine is performing, this is all the tuning you need to get started with very good results. Further tuning might be required to achieve a specific goal, other settings not approached here are not essential and can worsen the print quality if not done correctly.