Information about Minvayu's polar printer board and firmware configuration. The MinvayPolarPrinter runs on a DuetWifi board v.1.26 with RepRapFirmware v.3.4.1. It is a 3D printer for architectural purpose with a central rotating axis (similar to a crane).
See Getting connected to your Duet for detailed information.
The best way to communicate with the board is the DuetWebControl interface. DuetWebControl can be used to control the board using a computer or smartphone connected to the same wifi point. With this interface, it is possible to send gcode lines, run gcode macros, change configuration, start printing work and even handle height maps. See Duet Web Control Manual for more information.
To access DuetWebControl on a new wifi network, it is firstly necessary to communicate some gcode to the Duet board using another interface. To do that, it is possible to use the GUI interface cutecom on linux (or YAT on windows) after wiring the board to the computer.
Then, the user can connect the board to the wifi using M552 and M587 commands.
After connecting, send M552 S1 to get the IP address and connect to the DuetWebControl by typing the address in the browser.
A local name address is also created: our DuetWebControl MinvayuPolarPrinter interface can be accessed using the following link http://www.polarprinter.local (note that the board needs to be powered up to access the interface).
For example, the Duet board is already connected to the csair wifi (in CSR) and can be accessed from any device connected to csair by accessing the link http://www.polarprinter.local
The MinvayPolarPrinter uses the RepRapFirmware v.3.4.1 (main Github page and releases page) with a polar kinematics configuration.
Polar kinematics configuration is intended to be used for a turntable polar printer, but it can also be used for our purpose, considering the whole universe as a turntable. The polar configuration was done by following the steps of the PolarKinematics configuration page. Most of the work was done by the M669 command, that sets parameters such as radius limits and turntable speed. It was also important to adapt the homing files, depending on the homing system (z probing or z endstop homing system?
In the RepRapFirmware c++ code, M669 K7 will set the current
Kinematicsclass toPolarKinematics. Then, during run-time, the program will call theKinematics::CartesianToMotorStepsandKinematics::MotorStepsToCartesianfunctions that will realize the polar/cartesian conversions (calling atan2 and sqrt functions at runtime).
For the whole printer configuration, information on the mechanical details of the printer are needed. Potential required information are listed in the Required information page.
To upload those information into the board, the user needs to edit the following lines in the config.g file (it can be edited through DuetWebControl without turning off the board):
- Drive directions:
M569 P[drive number] S1; physical drive [drive number] goes forwards
M569 P[drive number] S0; physical drive [drive number] goes backwards - Motor speeds:
M92 X[r speed] Y[theta speed] Z[z speed] E[extruder speed]; set steps per mm (Y is in steps per degree)
M566 X__ Y__ Z__ E__; set maximum instantaneous speed changes (mm/min) - Polar configuration:
M669 K7 R[r min]:[r max] H[r homing switch] F[theta max speed] A[theta max acceleration]; with F in deg/s and A in deg/s^2. The user might also want to use the T and S parameters, see M669. - Axis Limits:
M208 X[x min] Y[y min] Z[z min] S1; set axis minima
M208 X[x max] Y[y max] Z[z max] S0; set axis maxima - Z-probes and probe grid:
See the Bed compensation section.
The user might also need to change the homing files because the homing values used might be to low for the actual printer.
It is possible test the motors individually by using the relative mode (G91 command) and then using the G1 command with H2 parameter to move individual motors. In the relative mode in polar configuration, the X parameter stands for the radius axis whereas the Y parameter stands for the rotational axis (the Y value must be specified in degrees).
The user can upload they own gcode files into the board using DuetWebControl interface.
A simple way to create gcode files is by using common slicer software (Cura, PrusaSlic3r, Slic3r) which can be configured for a round bed shape. However it doesn't seem possible to configure those software to check if the print object is inside our annulus printing area or not.
We created a python script for this purpose (see check_polar_gcode.py).
The user can also use the generate_polygons_gcode.py python script to create simple gcode for 2D polygonal structures in order to test the xy-plane movement. Other 2D gcode generator scripts ar listed in External scripts section.
Main help links concerning servo motors and Duet boards:
- Connecting external servo motor drivers
- Connecting hobby servos and DC motors
- Controlling unused IO pins
- How to connect integrated servo motors (forum talk)
“You can connect servo drives with step and direction inputs to the Duet just like regular external stepper drivers. They are likely to need 5V drive to the step, direction and enable inputs, so you will probably need the breakout board”
-- dc42 in DUET3D --> servo motor (forum talk)
It will be easier to power the servo motors with a separate power supply to avoid voltage/current issues.
After connecting the servo, we will need to configure it in the config.gd file. Use the M584 command to remap the axes and use the appropriate M569 commands to configure the drivers, step pulse timings, closed loops etc. This parts seems a bit tedious and needs details and information.
See the mesh bed compensation page. Use the M557 command with the R parameter for configuring a round bed grid in the config.gd file. Use the G29 command to probe the bed, load height map from file, disable mesh bed compensation or save height map.
Summary of gcode commands related to mesh bed compensation
G29Run file sys/mesh.g, or if that file isn't found then doG29 S0G29S0 Probe the bed and save height map to fileG29S1 Load height map from fileG29S2 Clear height mapG29S3 P"filename" Save height map to fileG30Probe the bed at a single point (can be used to measure Z probe trigger height)G31Set Z probe trigger height, threshold and offsets from the print head reference pointG32Run sys/bed.g file. You can put commands in bed.g to perform mesh bed leveling, e.g.M401followed byG29 S0followed byM402.M374Save height map to fileM375Load height map from file (same asG29 S1)M376Set bed compensation taper heightM401Deploy Z probe (runssys/deployprobe#.gfile where # is the Z probe number, or file sys/deployprobe.g if that file isn't found).M402Retract Z probe (runssys/retractprobe#.gfile where # is the Z probe number, or sys/retractprobe.g if that file isn't found)M557Define the probing gridM558Set Z probe type, dive height, probing speed, travel speed between probe points, and probe recovery timeM561Clear height map (same asG29 S2)
The user can also modify the retractprobe.g and the deployprobe.g files that are respectively called before and after probing.
Currently, the board is configured with an endstop probing system. the endstop is connected to the e0stop pin.
This directory contains two handmade python scripts:
Take a gcode file as input and check if the nozzle xy-coordinate movement stays between a distance of minradius and maxradius from the origin.
As Cura, Slic3r and PrusaSlic3r can't check if the print object is inside our annulus printing area, it is possible to use this script on the resulting gcode file to check if the print will be valid.
Usage : pyhton3 check_polar_gcode.py gcode_file [-r minradius] [-R maxradius] [-Ox origin_x] [-Oy origin_y] [-d] [-v] [-h]
-r minradius: set the minimum radius (default is 0.0).-R maxradius: set the maximum radius (default is +infinite).-Ox origin_x: set the origin x coordinate (default is 0.0).-Oy origin_y: set the origin y coordinate (default is 0.0).-debug -d: enable debug.-verbose -v: enable verbose (print the encountered issues).-h --help: print help information.
Print the gcode lines that went wrong using the verbose mode (-v parameter). Use the -r, -R, -Ox and -Oy parameters to define the annulus printing area.
The script also plot the xy-coordinates nozzle path with colors depending on the encountered issues:
- yelow lines are G0 rapid movement segment. Those segments can also raise issues even though it might not be a problem in practice (as G0 segment mostly represent non extruding rapid movement).
- green lines are valid segment.
- blue lines are non-valid segment crossing the inner radius area.
- red lines are non-valid segment crossing the outer radius area.
- purple lines are non-valid segment crossing both the outer and the inner radius area.
Generate a gcode file corresponding to the print of regular polygons in the xy-plane.
The script take parameter lines in standard input and write gcode lines in the standard output.
In the MinvayuPolarPrinter project, we use this script to create gcode file to test the xy polar movement.
Usage : pyhton3 generate_polygons_gcode.py [argument_file] [-nohoming] [-d] [-h]
optional arguments:
-nohoming: avoid the G28 command at the beginning of the generated gcode_file.-d: enable debug mode.-h --help: print this message
The user can use a file as input or use keyboard input as argument: simply use python3 generate_polygons_gcode.py and type the argument lines on keyboard (to exit keyboard input, type 'END' or 'EOF').
The user might want to redirect the output to a gcode file: in bash, python3 generate_polygons_gcode.py argument_file > gcode_file will do the job. For example: python3 generate_polygons_gcode.py test.datafile > test.gcode
The parameter lines should follow the following pattern: order radius origin_x origin_y (where order is the number of points).
The three last arguments can be ommited: default radius is 1.0, default origin is (0.0,0.0).
For example, the line ''4 1 3 0'' will represent a square of radius 1.0 centered at (3,0). Hence, the coordinates of the square points will be [(4,0),(3,1),(2,0),(3,-1)].