Area 49

This page outlines the method of using the LulzBot Taz 6 Dual Extruder Tool Head for printing a single item in two different colors. While the general concepts of printing with a single extruder tool head apply here, there are specific settings necessary in the model and in the slicer program for using a dual extruder.

Using the dual extruder requires two separate model files that will be merged in the slicer program.

LulzBot Taz 6 Dual Extruder Tool Head v2

Location: Makerspace, LulzBot #4

Lanyard color: Green

Use options:

• Training
• Request a print

Cost

• $0.25/gram
• $1 minimum

While these instructions are for the TinkerCad program, they can be used as a guide for what to do in any CAD program.

1. Design the model.
2. Group all parts you wish to appear in color 1 (select each component and click “Group”) and do the same for color 2. You should have two separately-grouped sections of your print in two different colors.
   • Note: If any faces of the model are showing two colors, your model may print incorrectly. Modify your model so that only one color shows per face.
3. Export two .stl files -- one of each color.
   1. Delete all parts of one color and export the model.
   2. Undo the deleted action and delete all parts of the other color. Export the model.
   3. Undo the deleted action to bring back the entire print.

You now have two .stl files that you will use in the slicing program.

If you haven't already, add the dual extruder to Cura.

1. Ensure you have the latest Cura LulzBot update.
2. In Cura, choose Settings > Printer > Add Printer, and select “LulzBot Taz 6 Dual Extruder v2” > Add Printer.
3. Activate LulzBot TAZ 6 Dual Extruder v2 (current activated printer will be in italics)
4. In Machine Settings, move to the Start GCode box. Delete all content from the box, and replace it with the following content. (This takes out the auto leveling and wiping steps and eliminates probing errors.) Select Close.
5. Change the materials for both extruders 1 and 2 to “PLA (Verbatim)”

Copy the following into the Start GCode box:

Pre-Set Dual Extruder Profile

Assign extruders

1. Load both STL files into Cura
2. Click on each model and assign one to Extruder 1 (Ctrl+1) and the other to Extruder 2 (Ctrl+2)

Merge Model

1. Select all models you want to be merged by holding shift, and left clicking each one.
2. Now right click either model and select “Merge Model.”
3. You should now see two shades of yellow on your mode which represents the two different extruders. If not, go back to step 2 and make sure you properly assigned each model to the correct extruder.
4. Continue selecting other settings as usual.

On the printer:

Changing Filament:

Heat one extruder, change the filament, and then heat the other extruder and change the filament.

Quick Info:

- Both extruders will be the same temperature, unless specified differently in Cura.

-Hot End 1/Extruder 1/Extruder 00 is the back, right extruder and Hot End 2/Extruder 2/Extruder 01 is the front, left extruder.

Enable these settings in Cura’s Custom Settings: Custom > Dual Extrusion > Enable Prime Tower or Enable Ooze Shield

Prime Tower

The prime tower is an extra tower on the build plate to prime the nozzle properly before printing the next layer. It reduces oozing and under-extrusion and enhances overall printing quality. The prime tower has a few settings, which are explained below.

• Prime tower size: The size in X/Y direction of the prime tower. A larger footprint creates a more stable prime tower, but uses more filament.
• Prime tower minimum volume/thickness: The volume must be enough for the nozzle to prime properly.
• Prime tower X/Y position: The position of the prime tower as seen from the origin point in Cura. It is located near the switching bay by default, to reduce printing time.
• Prime tower flow: The overall flow of the prime tower. This is set to 100% by default.

Fig. 1. Prime Tower. Retrieved from https://ultimaker.com/en/resources/49701-dual-extrusion

Ooze Shield

The ooze shield is a separately printed one-layer wide wall, which catches ooze from incoming nozzles before each layer is printed. It is recommended to only use this setting when printing with the Ultimaker Original Dual extrusion experimental kit. It has two separate settings to control:

• Ooze shield angle: The maximum angle of the ooze shield. This is to prevent the shield from collapsing.
• Ooze shield distance: The distance between the ooze shield and the model, to prevent the shield from merging with the model.

Fig. 2. Ooze Shield. Retrieved from https://ultimaker.com/en/resources/49701-dual-extrusion

Supports

Supports can be assigned to a specific extruder in Custom > Support. Use this option if you are running low on one color of filament.

Leveling the extruders/hot end

If you notice that the two hot ends are not leveled with each other and it’s affecting the print quality, follow these steps:

1. Manually move the extruder X-axis to the middle
2. Manually move the bed/build plate back just enough for the front hot end to touch the front edge of the bed/build plate
3. Using the LCD screen, go to menu > movement > move Z axis > 0.1mm
4. Move extruder all the way down to where it almost touches the bed and there is enough space to manipulate the screw. The goal is to level the front hot end with the back hot end. At this point you should be able to see whether or not the front hot end needs to move up or down.

​

Figure 1. Level Tool Head

Retrieved from https://ohai.lulzbot.com/project/TAZ-6-dual-extruder-v2-tool-head-installation/accessories/

5. It’s only possible to adjust the front hot end to the back one, therefore, use the 4mm Allen wrench until the two nozzles are the same height above the bed. Turning the screw counter-clockwise lowers the front nozzle. Turning the screw clockwise raise the front nozzle
6. Once they appear to be even with each other move the hot end down to where it lightly touch the bed. Now you should see if they are truly even or not. If not, make adjustments accordingly.

Error message "Probing Failed" or "Probing Halted" or extruder is printing in air

1. Raise the tool head off of the bed. If the Z motors  will not allow you to move the Z axis up, turn off the printer and manually turn the silver couplers that attach the Z axis motors to the threaded rods until the head is high enough off of the heat bed to do a measurement.
2. Measure from the top frame to the top of the X carriage guide rails . If either side is higher than the other, disable the stepper motors from the LCD display, or connect to printer to a computer using USB and choose "motors off" in Cura. Then manually adjust the higher side as equal to the other side. You can do this by turning the silver rods that attach the motors to level them.
3. There are also 2 screws on the Z carriage idler and the Z carriage motor that will need adjustment. Follow the guide rails that the tool head is mounted on to the assemblies that hold them in place. You will find two 4mm screws that hold the assemblies to the threaded rods. Loosen these two screws on the left and the right.
4. Auto home the printer.
5. Move the Z axis close to the top of the printer using CURA (245mm from home) or using the LCD display (Movement > Move Axis > Move 1mm > Move Z). Then auto home the printer again. Do this two times bottom to top and back. Then move the Z axis to the middle of the printer. Once the X carriage is in the middle of the printer, re-tighten the four screws connected to the Z nut mounts on each side.

If the prime tower doesn't adhere to the bed

• In Cura, add a brim

• Increase the prime tower volume by 2-3 mm^3

• Increase prime tower size