Printerbot Bed Visualizer
A python script for visualizing the surface geometry of a printerbot's bed using the onboard capacitive sensor. It will most likely also work for plenty of other printers provided you tweak the settings a bit.
If requested this script will apply the printer's G29 compensation, allowing you to see how effective the automatic bed leveling is. The script is compatable with both the stock printerbot firmware and modern_marlin firmware.
Also included is a simple fixture for mounting a dial indicator to the capacitive sensor. However, I found the onboard capacitive sensor to be repeatable to within +- 0.25 thou, so I would stick with that unless you are worried it is failing.
installation
I use ubuntu and have only somewhat tested the executable under windows. I recommend running the script as a python script under ubuntu, but it should work as an executable under windows as well. The two executables (windows and ubuntu) are updated only periodically. If you need a feature that doesn't seem to be in the executable version but is in the script feel free to open an issue or generate your own executable with pyinstaller.
Executable Install
Comming soon
Full Install
Clone the repo to a machine running ubuntu or windows with python 3. Then install the dependencies below.
pip3 install matplotlib
pip3 install numpy
pip3 install pyserial
pip3 install pyinstaller # Optional, only if you plan to make executables
Dial indicator
The included STL is suitable for use with a shars dial dial indicator with a 3/8 shoulder. The screws are 4-40x5/8 and the knuts are .24in edge to edge, although the corresponding M3 hardware may work with some persuasion. The part is not settings sensative and can be printed with standard .8mm walls and 25% infill. The included STL will print both halfs of the clamp in one print and they can then be pried appart with a knife.
The mount is designed in solidworks and can be eddited in any solidworks more recent then 2017. You may also have some luck with onshape (which is free and quite good) although I have not tried it for this particular part.
Usage
After completing the installation (above) the script can be run from the command line as follows. Your arguments (below) may be different depending on what exactly you want to do.
Run as a python script
python3 meshscan.py -v -x 150 -y 150 -s 25 -l -p /dev/ttyACM0
Run as a ubuntu executable
./meshscan -v -x 150 -y 150 -s 25 -l -p /dev/ttyACM0
Unless your system is very similar to mine you may need to change the port and baud rate arguments. The baud rate is a product of the firmware installed on your printer, and the comport is a product of the order in which devices are connected to your computer. Both can be found in your g-code sender. A good default comport for ubuntu is '/dev/ttyACM0' and a good default guess for windows is 'COM0'.
Reading the plot
The heat map is annotated with the "height" of each probe point relative to the lowest position probed. When using the script in G29 compatability mode, the "height" used is given by [measured bed height] - [bed compensation offset]. This means that areas that read as higher (more yellow) on the chart will tend to have a nozel closer to the bed and areas that read lower (more blue) will tend to have the nozel farther from the bed.
In general, a difference of more then about .05 is probobly cause for concern.
saturation
Saturation (large areas of the heatmap returning identical values when you know that not to be the case) can occur in two cases as follows:
Low valued saturation around the heatmap edges may occur when your firmware has been set to prevent probe use near the bed edges, or when an offset has been defined between the probe and the nozzel. These settings are set in firmware and short of re-flashing the machine there is nothing to be done about it. adjusting the bed dimensions and step size can remove these areas from your chart if desired.
High-valued saturation may occur When there is a really big difference (~ 2mm) between different parts of the bed, or when you have a large default z offset then parts of the map will saturate. To fix this tweak the PROBE_HEIGHT paramiter up, or open an issue. Note: Areas that saturate may actually be significantly lower then the value on the chart.
Command Line Arguments
| Parameter | Default | Description |
|---|---|---|
| -v, verbose | False | prints out extra info. |
| -l, leveling | False | Apply compatability with G29 height compensation (doubles run time). |
| -m, modern_marlin | False | Sets the scan to run with parsers conpatable with the modern marlin G30 output format. |
| -b, baud | 250000 | baud rate for serial transmission. (firmware specific) |
| -p, port | /dev/ttyACM0 | COMPORT to use for communicating with the printer. |
| -x, x_limit | 150 | size of area to scan in mm. |
| -y, y_limit | 150 | size of area to scan in mm. |
| -s, step | 25 | linear spacing along each axis between probe locations in mm. |
Start and end files
Place your machine's startup g-code into the startup.txt file. This will be run prior to the scan. Use this to run any commands (say homing or bed leveing) run prior to printing. If you are copying over code from cura's printer settings take care to REMOVE any that relate to the extruder.
Do the same thing for your machine's ending g-code. This won't impact the scan results, but you may find it convenient to have it home or zero after use.
The comment handeling is very much an afterthought so if you run into trouble consider removing all of the comments from your startup and shutdown scripts. Also, if either of these files takes longer then ~20s to execute you may need to tweak that in code. (It's unlikely though)
Issues
If you run into problems using this code, or need help adapting it to another printer please create a github issue and we'll get it sorted out.