5.2 Dual Extruder Calibration

If your printer has only a single extruder, or if you never use two extruders for the same print, then you can skip this section.

When printing with both extruders, optimal print quality is achieved by precisely calibrating the distance between the two extruder nozzles. As explained in Section 4.2, this calibration information is stored as the “toolhead offsets”. In this section, a method of determining the toolhead offsets is presented. For every major type of printer, there is a nozzle calibration print in “ReplicatorG 40 – Sailfish”, that may be printed as described and then the results supplied to your printer. Using the results of your print, your printer will then set the correct values for the toolhead offsets.

Before you begin, ensure that you have the latest Replicator G 40 – Sailfish downloaded from the Sailfish “Thing” at Thingiverse.
Launch ReplicatorG and select the correct machine type under the “Machine Type” item of the “Machine” menu. Be sure that the machine type name includes “(Sailfish)” in it. Figure 5.5 shows The Replicator Dual (Sailfish) selected.

Figure 5.5: Machine Type

Connect to your printer over USB (see Figure 5.6), then invoke the Onboard Parameters window with the “Onboard Parameters” item of the “Machine” menu.

Figure 5.6: Connecting to Your Printer

In the “Homing/VREFs” tab, set the X and Y toolhead offsets to 0.0 mm. Be sure to change the toolhead offsets and not the home offsets (Figure 5.7). Make sure to commit the change. Note that resetting the printer to factory defaults will not reset the X and Y toolhead offsets.

Figure 5.7: Toolhead Offsets

To print the nozzle calibration print go to the “Scripts” item of the “File” menu, choose your printer type, and then select the “Dual Nozzle Calibration.gcode” item (Figure 5.8). Select the Replicator 1 if you do not see your printer type listed. Note that the name may be an elongated version of this such as “Flashforge Creator Dual Nozzle Calibration.gcode”. Regardless, selecting this will bring up the gcode file in ReplicatorG which you should then print to your printer.

Figure 5.8: Nozzle Calibration Menu

Once the print is finished, you will see a series of horizontal line pairs running vertically up the left side of the build plate (Figure 5.9). Each pair of lines was printed using both extruders, and is numbered with a value between 1 to 13. Line 1 is at the front of the plate and should be the longest. Identify the pair for which each line is vertically the best aligned. Remember this number. In the example print of Figure 5.9, either lines 1 or 2 seem to have the best alignment.

Figure 5.9: Nozzle Calibration Print

The print will also have a series of vertical line pairs running horizontally across the front of the build plate. Again, each pair of lines was printed with both extruders, and are numbered 1 to 13. Line 1 is the leftmost and should also be the longest. Identify which pair has the best alignment — which pair has the middle ends closest horizontally. Remember this number. In the example print of Figure 5.9, pair 6 appears best aligned.
On the printer’s LCD screen navigate to the “Calibrate Nozzles” item under the “Utilities” menu (Section 3.7.18). For the X and Y values, input the numbers you recorded for steps 7 and 6, respectively. Then select the “Done” item on the fourth line of the screen.
Your toolhead offsets have now been set. The values in ReplicatorG’s Onboard Preferences will have changed unless you entered 7 for both X and Y, as Line 7 represents the ideal offset of 0.0 mm. The actual lines are offset by by -0.6 mm, -0.5 mm, ..., 0.0 mm, 0.1 mm, ..., 0.6 mm, creating thirteen offsets total.

Note, however, that, should you revisit the Calibrate Nozzles item on your printer, you will not see the X and Y values you entered, as the printer does not save these values but instead uses them to recalibrate. It is worth mentioning that, after recalibration, these values are no longer correct: if you were to reprint the nozzle calibration print, you should now find that Line 7 is the best match for both X and Y.