Auto_Bed_Leveling: Enhanced G29 command

[hdfritz]

applying an R code that I found here:

http://www.r-bloggers.com/plot-3d-topographic-map-in-r/


I quickly produced the following image of my printbed's topography:



Now of course there is a legend missing which tells you more about the colourcoding and hence the value you need to correct but:
I think this allready tells you very quickly how to adjust your printbed, doesn't it? Just as a comparison my output:

-0.23168 -0.19443 -0.18793 -0.10518 -0.08943
-0.16093 -0.11218 -0.05593 -0.10193 +0.02907
+0.01082 +0.03307 +0.09357 +0.05157 +0.12532
-0.08143 +0.04857 +0.10532 +0.11907 +0.16432
-0.05343 +0.05657 +0.14907 +0.16682 +0.22132

I hope, I got someone interested in helping me out!

[tsteever]

I found where the raise 15 is coming from and I lowered it to 10 to give it a shot. What I am having trouble with is the G28 command. After issuing the G28 I measure the height. The lcd display shows 12.8. This is the 10mm raise plus my offset.

Trouble is, when I issue a G1 Z0 the nozzle is still above the bed by the z offset amount. Kinda like the offset gets added twice.

[Roxy]

I found where the raise 15 is coming from and I lowered it to 10 to give it a shot. What I am having trouble with is the G28 command. After issuing the G28 I measure the height. The lcd display shows 12.8. This is the 10mm raise plus my offset.

Trouble is, when I issue a G1 Z0 the nozzle is still above the bed by the z offset amount. Kinda like the offset gets added twice.

And if you do a G28, and then a G29 and then a G1 Z0 what happens?

[Roxy]

applying an R code that I found here:

http://www.r-bloggers.com/plot-3d-topographic-map-in-r/

...

I quickly produced the following image of my printbed's topography:
I hope, I got someone interested in helping me out!

Yes, the grid of numbers should be very helpful to get your bed manually leveled. Just push down any corner that is + and pull up any corner that is -. I don't have time to mess with stuff right now but I want to check out that link you used to plot your print bed.

[tsteever]

A G28 followed by a G29 seems to work fine. The G28 is not working. There are times I just use a G28 to manually calibrate the bed and I would like it to actually read correctly. When I do a G28 the printer goes through the homing procedure and when it has found the z axis zero point the LCD changes from 0 to 10 and raises up 10mm (This is the number I have it set to). Once it has raised the 10mm the LCD adds 2,8 (my offset).

Now, if I issue a G1 Z0 command the axis will move down until the LCD says 0 but it is actually a few mm above the glass still. This distance is approximately the same as my offset value. It is as if the offset is added twice but only reflected twice on the LCD.

[Roxy]

A G28 followed by a G29 seems to work fine. The G28 is not working. There are times I just use a G28 to manually calibrate the bed and I would like it to actually read correctly.

This is what I suspected. There has been a bug in the G28 / G29 pair since G29 was added. The pair work correctly. But individually, the G28 gets confused. I think this is fixed in the main Marlin branch now but I have to verify that.

[tsteever]

I sent you a PM, thanks again for your help. I will wait patiently to hear back from you as it would be nice to just run a G28 at times when I am only printing something small.

[sniffle]

It's probably going to take a little more effort than just copy/pasting things in... htere have been a lot of changes to the ABL code since this was written Roxy.

Once i get this into the current codebase would a few people mind testing it?

[Roxy]

It's probably going to take a little more effort than just copy/pasting things in... htere have been a lot of changes to the ABL code since this was written Roxy.

Once i get this into the current codebase would a few people mind testing it?

Sniffle, Are you starting with the most current Erik Zalm branch? If so... as soon as you get it crossed over I'll load it on my printer. Are you a GetHub user? If it works, can you try pushing it back for Erik Zalm to approve?

[sniffle]

Sniffle, Are you starting with the most current Erik Zalm branch? If so... as soon as you get it crossed over I'll load it on my printer. Are you a GetHub user? If it works, can you try pushing it back for Erik Zalm to approve?

It's not Erik Zalm Branch anymore...

https://github.com/MarlinFirmware/Marlin

yes that's my plan, to have it approved and be merged into the firmware from here on...

things have changed a lot in the case 29 code