A basic question about how Mesh Bed Levelling works // the G80 command
Hello all on the Prusa forums.
I've been lurking here a while - and have just found myself with a Mesh Bed Levelling question I can't quite find the answer to.
In short: Is it just the G80 command that forces compensation for bed levelling in a print?
Slightly longer version;
I've been playing around turning my MK3S into a pen-plotter, to draw diagrams, etc. I'm generating GCode through an inkscape extension from SVG files basically. And so basically, there is no 'start up code' to do a Mesh calibration, or anything else.
What I'm finding is high/low spots in these drawings that correspond to the high/low spots after running the mesh bed levelling command (and getting a heatmap through octoprint).
What I'm not quite sure of is what tweaks I need to make the Gcode I'm generating to fix it through bed levelling.
If I just stick a G80 command before the 2D plot, will that make the compensation happen automatically, or is there some other magic happening somewhere that forces the compensation?
Hope that makes sense - let me know if I can clarify anything. 🙂
RE: A basic question about how Mesh Bed Levelling works // the G80 command
Alrighty, I think I solved it.
Firstly I tried copying some other gcode, including a G80 command, to do a mesh bed level before starting to draw. I still got choppy results.
Turns out, I was also including a G28W command, which I believe resets the mesh. And of course this was after the G80.
Getting rid of that gives a much improved result - left is the original with low spots, right is with G80 working.
RE: A basic question about how Mesh Bed Levelling works // the G80 command
@simms
OK
I'll bite.....what 2D software are you using to get those results?
RE: A basic question about how Mesh Bed Levelling works // the G80 command
So... Lots going on (happy to post more depth if useful..) but:
First generated a Map with just black lines for Roads / Water / Land Boundaries using google Styling Wizard ( https://mapstyle.withgoogle.com/) - 3 maps with just those 3 single things.
Imported those maps (as a PNG) into Inkscape, and converted it to a vector.
Then using the "KM Laser" extension in inkscape, turned any 'filled' area into a hatchbox (i.e. the blue water you see in the image).
Saved each colour layer down as a separate SVG.
Then I used Plotify2D ( https://plotify2d.com/) to convert each SVG into GCode - and went from there. It's a subsription, but I wanted to try i t for a month to see if I can get any use from it. The image above has the Gcode as it spits out (Left) and after including G80 for mesh levelling (Right)
There's also an inkscape extension to turn an SVG into GCode, but I didn't find it particularly reliable.
I also designed a pen-holder to go over my Extruder motor (here) - holds in place fairly well.
Works pretty well 🙂
RE: A basic question about how Mesh Bed Levelling works // the G80 command
@simms
I can't say for a 100% certainty, but I'm 99% confident G80 by itself is the command that invokes the mesh leveling that sums Live-Z, bed compensation matrix, and result from the PINDA measurement matrix and slowing integrates back to 0 a few millimeters into the build.
Options N7 increase the sample points to a 7x7 grid, and R5 repeats measuring each sample point 5 times to improve accuracy.
G80 N7 R5 ; mesh level
RE: A basic question about how Mesh Bed Levelling works // the G80 command
@simms
Thanks for the update. I am off to start this new project with the information you provided.
RE: A basic question about how Mesh Bed Levelling works // the G80 command
@1agkirk2
Good luck - hope it works out! I've been 2D-printing a few things since I solved my G80 issue - and I think I have Christmas gifts sorted.
This my favourite so far.
I'm also making a Version 2 of my pen holder, to be a bit sturdier / have tighter clearances / hold wider pens.
RE: A basic question about how Mesh Bed Levelling works // the G80 command
@simms
Nice What pens are you using?