Auto_Bed_Leveling: Enhanced G29 command

[DarkAlchemist]

Almost for sure you will need to do some fine tuning of the Z-OFFSET number in Configuration.h I would tell the Slicer to add a G28 and a G29 u 3 v to the start of your GCode. I would try to print something and see if the nozzle is the correct height to get the first layer down correctly. That is the really nice part about the Auto Bed Leveling. Once you have the Z-OFFSET set correctly, the first layer almost always goes down perfect.

If the first layer looks like it is going down correctly, watch the Z-Axis screw threads. You should see them turn back and forth a little bit depending on what the X & Y are doing. The back and forth movement should be very consistent depending upon how far and which direction the nozzle is traveling in a 'corrected' dimension.

I am not sure what you mean about the Z-Offset numbers will have to be changed? That 0.3 is precisely how far off my nozzle is from the probe (for now until the new switch and arm are installed).

[Roxy]

Well... It seems any time I make changes, I have to dial in a new Z-OFFSET number. But if what you have works... Of course there is no reason to change it. Just changing the Homing Speed seems to affect the required spacing for me. Mostly, if the spacing is off a little bit, I wanted you to understand that isn't a big surprise.

[DarkAlchemist]

Well... It seems any time I make changes, I have to dial in a new Z-OFFSET number. But if what you have works... Of course there is no reason to change it. Just changing the Homing Speed seems to affect the required spacing for me. Mostly, if the spacing is off a little bit, I wanted you to understand that isn't a big surprise.

Ahhh, yes, but if it is laying down the extruded filament in mid air, as it was doing, then there is an issue.

Shouldn't I be seeing what my bed is before I attempt to print? I forgot what I did so I could do a scan in each corner and it would show me a grid of numbers.

[Roxy]

Do a G28 and then a G29 u 4 T

That will give you a matrix of numbers. (T gives you the bed topology) If you have the origin of your bed declared in the correct corner, you should be able to just visually overlay that matrix of numbers to know which corners are high or low. It is very helpful to manually level your bed almost to perfection.

And yes, it would be good to do a G28 and G29 and check things prior to printing. But my bed is on springs and I usually have my finger on the Reset button when I start things after making changes. Probably, it would be wise to do a G28 and G29. Then use PronterFace to lower the nozzle a little at a time until you are at a height of .2mm or .3mm and use an M114 command to verify everybody is in agreement. If so... lower the nozzle until it just touches the bed and once again use the M114 to see if the Marlin Firmware is in agreement. But like I say... My bed is on springs and I just go for it with my finger ready to reset it.

[DarkAlchemist]

I can't get this level. The boro glass is dead flat but the pcb is warped. So I clamp the pcb to the glass but to tighten any screws will only spell hours of aggravation.

As far as G29 it starts in the left upper corner, goes down to the lower left corner then over to the right lower corner and ends at the upper right corner. It always tries to end at the upper right corner so I hope that is my origin.

Bed Height Topography:
--1.58886 --1.40236 --1.64611 --1.21386
--0.56736 --0.41636 --0.27811 --0.24361
+0.27764 +0.53039 +0.55914 +0.41139
+1.08064 +1.34464 +1.68414 +1.46864

[Roxy]

As far as G29 it starts in the left upper corner, goes down to the lower left corner then over to the right lower corner and ends at the upper right corner. It always tries to end at the upper right corner so I hope that is my origin.

Where ever it does its first probe (not the G28 probe), that will be the origin. You are not using the same words I would use, but it sounds like you should have the #define ORIGIN_BACK_LEFT enabled.

I can't get this level. The boro glass is dead flat but the pcb is warped. So I clamp the pcb to the glass but to tighten any screws will only spell hours of aggravation.

One word of caution. If you have the wrong #define ORIGIN statement enabled, it is going to print the topology map in the wrong orientation. If you try to use that information to manually level the bed without compensating for the wrong orientation, you will never get it level. Once you think you have the orientation correctly #defined you can just pick one corner and raise or lower it. You should see improvement in that corner and see the topology map move in the direction you adjusted things.

Also, after you do the G28 and G29, in PronterFace (and probably other client consoles) you can tell it to Home the X & Y. The corner it goes to is going to be your origin. (Unless you have setup your printer to home towards max end stops and such. Right now, that is not the case for you.)

Bed Height Topography:
--1.58886 --1.40236 --1.64611 --1.21386
--0.56736 --0.41636 --0.27811 --0.24361
+0.27764 +0.53039 +0.55914 +0.41139
+1.08064 +1.34464 +1.68414 +1.46864

This topology report is claiming the back side of the bed is much lower than the front of the bed. It looks relatively flat left to right. But it does raise a little going from left to right. If you have the orientation incorrect, things will be twisted and what I just said won't reflect reality.

One more note about being 'not flat'. The topology map is very helpful to know if you are not level and to know if you are not flat. Your flatness does not seem crazy. You can tell if you have a bulge, or a low spot because when you scan across any row or column of numbers you will go from + to - and back to +. (or vice versa) Your topology matrix doesn't do that. It is claiming your glass is pretty flat. When you get it more leveled, you will get better information about where any high or low spot is. (with it this out of level, the high and low spots will be much less than the tilt of the bed, and you probably won't see them. They are probably there, but are small enough you can't see them right now.)

You really should get the correct origin location defined and use the topology map to manually level your bed much better than it is right now. But even so... Your bed is not so crazy you can't print. You should be able to print with it that 'unlevel'. You should be able to see the Z-Axis correct as it moves the nozzle around on the bed.

[DarkAlchemist]

Judge not the actual numbers as my switch requires a lot of pressure to activate so it actually pushes the glass, and pcb, in and repeatability is out the window. This is why I have a new switch on the way (a mouse kind) that is ultra soft touch in comparison. Now do judge the sign of those numbers and considering I let the bed tell me how it wants to go instead of me trying to force it to bend to my will that is the best I can get it with a 4 point Prusa I3 Aluminum build.

As far as homing goes if I hit the middle button that homes X and Y the bed comes full forward (to hit the Y max endstop) and full right (to hit the X max endstop).

[Roxy]

I was mistaken... I just took a look at your Configuration.h file. You have:

// ENDSTOP SETTINGS:
// Sets direction of endstops when homing; 1=MAX, -1=MIN
#define X_HOME_DIR 1
#define Y_HOME_DIR 1
#define Z_HOME_DIR -1

So you are actually Homing to the max position. So, it may be your origin is at the Front Right ???? When you put an .STL file into Slicer and then try to print it, does it get rotated on your bed? Or does it print it in the same orientation that Slicer shows it?

[DarkAlchemist]

Same orientation and that makes me laugh because when I first made this printer I didn't know until I printed something with writing on it.

I was always told my 0,0 origin is front left but not really sure.

[Roxy]

Same orientation and that makes me laugh because when I first made this printer I didn't know until I printed something with writing on it.

I was always told my 0,0 origin is front left but not really sure.

If it prints in the same orientation as what Slicer shows it sitting on the bed... Your origin is at the FRONT_LEFT. I suggest you try re-compiling with that and doing the following:

• Do a G28
• Do a G29 u 3 T
• Do a G28 (To invalidate the correction matrix)
• Lower the nozzle to 1.5 mm above the bed. (because the Topography report you had up above said that was the max things got out of kilter)
• Move the nozzle to each corner and see what the spacing is. The corners in the Topography report that have minus numbers should have a bigger gap than the corners with larger positive numbers. If this is so, you will have proved the Topography report reflects what is really happening on your bed.

I think you should try doing a print! You are going to like watching the Z-Axis correct based upon what the X and Y location are at!