Auto_Bed_Leveling: Enhanced G29 command

[Fri]

Question how do I execute the command to auto bed level at the start of a print using Cura. Sorry im not a coder and some of the basics escapes me.

You must enter a G29 after the G28 in the prefix.
In other words, in you gcode, after the G28 you need to have a G29.

[beerdart]

So here is my Cura start I just add G29 after the G28?

;Sliced at: {day} {date} {time}
;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
;Print time: {print_time}
;Filament used: {filament_amount}m {filament_weight}g
;Filament cost: {filament_cost}
;M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
;M109 S{print_temperature} ;Uncomment to add your own temperature line
G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
G29
G1 Z15.0 F{travel_speed} ;move the platform down 15mm
G92 E0 ;zero the extruded length
G1 F200 E3 ;extrude 3mm of feed stock
G92 E0 ;zero the extruded length again
G1 F{travel_speed}
;Put printing message on LCD screen
M117 Printing...

Most slicers (including Cura) let you put start up GCode into the generated file. You want Cura to put a G28 followed by a G29 at the start of every file it generates.

You must enter a G29 after the G28 in the prefix.
In other words, in you gcode, after the G28 you need to have a G29.

[Roxy]

So, the moral to this story IS that ABL isn't really out of the way and I need to find a way to stab it, gut it, then kill it and bury it then bury the shovel while retaining the dynamic Z endstop that G28 gives with ABL on.

You have made it pretty clear you don't like or want Auto Bed Leveling... My suggestion is don't turn it on when you build the firmware.

[Roxy]

So here is my Cura start I just add G29 after the G28?

Yes, and You can manually verify that it is there in your GCode file after you slice something. But, you will see it probe the whole bed when you start a print.

[beerdart]

Thanks.. ..

[DarkAlchemist]

It is very obvious as I don't want it nor need it so I will have to find a way to rip out the best part of ABL (by the way I understand it is now called Bed Compensation) being the dynamic Z endstop. There has to be a way to separate the two completely.

[inventabuild]

Does the enhanced g29 command actually create a 3 dimensional topographical map with hills and valleys by which the hot end will follow or does it just create an average height from all the probed points?

Also, I have a TAZ 4 and would like to implement this from beginning to end. Is there an instructional page or video somewhere showing me all the parts needed, how to assemble them to the TAZ and how to implement the code with the current TAZ firmware?

[DarkAlchemist]

I am unsure but I do know this ABL will not work if you have any hills, valleys, dips, etc... Perfectly flat or else it doesn't work right.

[Roxy]

Does the enhanced g29 command actually create a 3 dimensional topographical map with hills and valleys by which the hot end will follow or does it just create an average height from all the probed points?

The Enhanced G29 code does produce a topographical map of the bed. It probes all the points and uses that to find the mean distance of the bed from the probe. When it goes to generate the topographical map of your bed, it subtracts off the mean from each measurement so you are seeing the +/- of that point relative to the rest of the bed.

This is very useful even if you don't want to use the Auto Bed Leveling on every print because it shows you which corners need to be raised or lowered.

Also, I have a TAZ 4 and would like to implement this from beginning to end. Is there an instructional page or video somewhere showing me all the parts needed, how to assemble them to the TAZ and how to implement the code with the current TAZ firmware?

There are a lot of good videos that show different implementations of the Auto Bed Leveling. One of the first was the Zen Master video that helped get everybody excited about Auto Bed Leveling. It is here: http://zennmaster.com/random-things/...nd-basic-setup

But I suspect there are better ones if you want to search for them.

I am unsure but I do know this ABL will not work if you have any hills, valleys, dips, etc... Perfectly flat or else it doesn't work right.

I disagree. You can tell if you have any bumps or dips by seeing if the numbers in your topology map flip from positive to negative and back again. Here is a report from my machine with the current piece of glass on the bed. Notice the numbers in RED. The sign of the numbers flip in both the horizontal and vertical (X & Y) direction.

Bed Height Topography:
--0.04743 +0.01475 +0.13580 +0.10868 +0.01740
--0.04776 +0.01607 +0.12422 +0.10239 +0.03195
--0.09935 --0.02990 +0.04782 +0.02236 --0.04412
--0.03585 +0.01078 +0.10140 +0.07164 --0.00245
--0.16847 --0.10597 --0.02725 --0.05305 --0.14367
planeNormal x: 0.00 y: 0.00 z: 1.00

The smaller the numbers you see in the bed topology report, the more level your bed is. What I posted isn't as flat as I usually have my bed, but I've been switching back and forth between different pieces of glass.

[inventabuild]

Great, thank you Roxy. How do people usually find the offset between the probe and the tip of the nozzle? And have you seen this offset number change over time with all the mechanical stuff going on?