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User guide to UBL?

Posted by DaveA 
User guide to UBL?
May 06, 2017 01:34PM
Is there a step by step set of instructions for using UBL? I'm using 1.1.0 with a BLTouch. Following the steps I think I need I initialized EEPROM, did a G29 P1 to create a mesh and saved it to EEPROM with G29 S0.
I activate UBL, load the mesh and then try to print but there is no obvious correction taking place. The only time Z moves is when changing layers.

Anything else do I need to do in my start print script?
Re: User guide to UBL?
May 06, 2017 03:56PM
Yes... All that sounds reasonable! You may need to do a G29 A to activate it. But... I've fallen into this trap several times during development. Is your nozzle more than 10mm above the bed? If you move your nozzle to 1mm above the bed, you will see movement if the system is active. You can look at your topology map by doing a G29 O

Or, if you want more extreme proof the system is working, do a

  • G29 P0 ; to zero the mesh
  • G29 Q1 ; to put a diagnol line across the mesh
  • G29 A ; to activate system
  • G29 O ; to view the test pattern
  • G1 Z2 ; to get the nozzle within the fade height
  • G1 X0
  • G1 Y 100
  • G1 X 150

You should see the nozzle rise as it hits the line and lower when it gets past it....

Incidentally... There is a Quick Start guide available now... Bob-the-Kuhn wrote it. If you search a little bit at www.github.com/MarlinFirmware/Marlin you should be able to find it.

Edited 2 time(s). Last edit at 05/06/2017 04:05PM by Roxy.
Re: User guide to UBL?
May 08, 2017 09:51AM
Incidentally... There is a Quick Start guide available now... Bob-the-Kuhn wrote it. If you search a little bit at www.github.com/MarlinFirmware/Marlin you should be able to find it.

I've been trying to figure out UBL all weekend without much luck. I found Bob-the-Khun's guide here: [github.com]

And that did seem to help me generate a mesh. But...doesn't really explain how to use the mesh.

With traditional bed leveling I just add a G29 after my G28 in my startup gcode and I get leveling.

What needs to be done once you've got a mesh to actually use it with UBL? The Guide doesn't really say. I see a new script generated 'buildroot/share/scripts/g29_auto.py' which has a comment at the top saying it's "for preprocessing gcode and the new G29 autobedleveling" and something about replacing "g29_keyword = ';MarlinG29Script' with "the new G29 LRFB" not sure if this is related to UBL or is an old thing left behind...I've never noticed the script before so I'm not sure.

I tried just using G29 A and that didn't seem to work...so I tried G29 A followed by G29 J 2; and that didn't seem to work either...I could see it probe before printing but then it raised the print head up and tried to print about an inch above the printbed and way off on the side of the buildplate instead of the center where it should have been.

The instructions on how to improve the mesh are also pretty sketchy still. I did a G26 and none of it looked great...but I'm not sure how to interpret it. I measured some of the extruded material and it was 0.20 which is what the G26 was supposed to do...but it wasn't a clean extrusion - lots of gaps. One corner of the mesh definitely looked like it needed to be improved - but the instructions on using P4 seem incomplete in Bob's guide. And reading the instructions in ubl_G29.cpp didn't help much either...it just says things like "Using the information left on the printer's bed from the G26 command it is very straight forward and easy to fine tune the Mesh" But doesn't really go into any detail about what you're supposed to do. It may be straight forward and easy if you understand the intent...but I can't find anywhere that it's all explained.

Looking forward to trying this - I'm getting better prints off 1.1.0 (and bugfix-1.1.x) than I was off RC6 which I had been running previously. And I'm very excited to try the new UBL stuff. Just lost since the documentation seems to be mostly written for people who are already familiar with UBL at this point.
Re: User guide to UBL?
May 08, 2017 11:37AM
Same here, went back to bilinear instead of UBL. Will try it again once there is a " UBL for dummies"
Re: User guide to UBL?
May 09, 2017 03:03PM
UBL User's Guide at: [marlinfw.org]
Re: User guide to UBL?
May 10, 2017 10:48AM
The UBL getting started guide is now available.

We will be changing the firmware so that the LCD is all that is needed to do 99% of the UBL bed leveling. The changes should be in the bugfix-1.1.x branch later today.
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