This guide will walk you through the process of calibrating the position of the T1 toolhead with respect to the T0 toolhead. This calibration is necessary for any prints which use both toolheads on the same model. This includes support material prints.
Calibration of the X and Y tool offsets must be done every time a hot end assembly (or toolhead) has been manipulated in a way that affects the nozzle’s relative position to the carriage. This is part of normal operation and the machine may require minor adjustments and recalibrations over time.
The objective of the calibration, is to line up the material printed by T1 with material printed by T0. Without this procedure, the two tools may be misaligned and the material printed by the two toolheads will be shifted in the X and/or Y axis.
Required Tools & Equipment
- the two spools of ABS filament included with the M2 printer
- calipers or other measuring tool
M218 G-code command will be used to modify the coordinate system of the T1 tool with respect to the coordinate system of the T0 tool. Please note, for this process, the T0 toolhead remains “static”, while the
M218 command changes the T1 position with respect to the T0 position. When changing the offset we are looking to move the printed features of T1 rather than T0 and treat the positioning of T0 as correct. The X offset obtained from the calibration represents the distance in X from the origin (placed at the front left corner of the build plate) to the nozzle tip of the T1 toolhead in its parked position, as shown in the figure below. The Y offset is simply the distance in Y from the nozzle tip of the T0 toolhead to the nozzle tip of the T1 toolhead, in their parked positions.
The following sections outline the detailed execution of the process summarized above.
Download the X and Y calibration G-code file. The file contains a simple square shape. The process is configured to have five “brim perimeters”. Temperatures have been set for use with AON3D validated ABS filament: 230C extrusion temperature, 105C bed temperature, and 80C chamber temperature.
If you haven’t already, load the two spools of ABS filament provided with your machine on T0 and T1. Note that the filaments are different colours to easily distinguish the printed features on T1 from the printed features on T0. You can also download the X and Y calibration factory file which allows you to create customized G-code scripts to accommodate dual toolhead calibration using filament material other than ABS. Once the G-code script is created, you can upload it to the printer.
Before starting a print, the printer must be at thermal equilibrium. Make sure to preheat the bed and chamber to the operating temperatures for your chosen material. For ABS, these are 105C bed temperature, and 80C chamber temperature. Operating temperatures for other AON3D approved materials can be found in the Materials documentation.
Once you hit print, each toolhead will print 5 “brim” perimeters. A brim is a single track of material deposited around the outside perimeter of a part. T0, the left toolhead, will print 5 brim perimeters first (blue). T1, the right toolhead, will then print 5 brim perimeters inside those printed by T0 (green).
At this point, the T0 tool will take over to print the first layer of the part.
For the rest of the print, T0 will print the perimeters while T1 prints the infill.
When the print finishes, the toolheads will move back to their parked positions in X. The hot ends are turned off so as to avoid clogging filament inside the heater block while adjustments to the offset are made. The chamber and bed heaters are left on to allow you to start another print shortly after.
All units are in mm!
Note the initial T1 tool offset:
M218 T1 in the terminal tab
b. Note the X and Y values output on the screen. An example output is shown below. If the X and Y values read “0”, the offsets have not been adjusted from their factory state, and will be X:526 and Y:0.
Start the calibration test print by tapping Print beside the calibration print G-code file in the files tab.
Observe the printing process. Note the position of the T1 print relative to the T0 print.
Once the print has finished, estimate or measure the T1 offset in X and Y. These will be
∆Y to the X and Y values from step 2. These will be your new X and Y offsets.
X offsetvalue will move features printed by T1 to the operator’s left
Y offsetvalue will move features printed by T1 toward the front of the printer
Y offsetvalue should be smaller than +/- 2 mm
X offsetvalue should be larger than 520 mm
M218 T1 X[X offset] Y[Y offset] G28 M500
M500 command saves the offset values entered.
Once you have calibrated the T1 X and Y offsets, it is necessary to probe the bed with T1 again to compensate for the changed probe positions in the X-Y plane.
< M218 T1 > Hotend offsets: X:0.00 Y0.00
The offsets have not been adjusted from factory state: X:526, Y:0
M218 T1 X529.5 Y-0.6 G28 M500
M218 T1 X529.3 Y-0.5 G28 M500
The X and Y tool calibration process is complete. You are now ready to start dual-material printing with your AON-M2.