HELP!!! Please I’m frying my little brain, I am just finishing up on a Prusa clone and I’m trying to sort out the auto bed levelling. I managed to get it to the point where I think it should be with an offset of 0.7mm from the probe allowing the nozzel to just rest on a piece of thin paper but when I ran the G28 G29 codes before the print started the nozzle ended up being about 1.5mm above the bed.
I used repetier to create my gcode and run it through Pronteface/Printrun, could I be right in thinking the settings within repetier have created a different offset for the G-code?
I know I should just use Slic3r or a different slicer but at this time repetier was easier for me. I’ve been looking around and I have seen things state something about the eeprom, Should I be saving my setting to this?
M501 will display configurable settings. Are you using a z probe or an endstop?
It’s a Probe, I was adjusting it in the marlin firmware but is this not where I need to be at this point then?
You’re not reflashing the firmware each time, right?
If eeprom isn’t enabled, make sure you enable it.
Then use the gcode M851 to set the probe offset. Then M500 to save to eeprom. M501 will let you view the settings.
@Stephanie_A I’m relatively new to this and this is the first printer I’ve built. I followed Tom’s 3d dolly tutorials but he doesn’t seem to go into the z probing settings.
I will check the eeprom setting and try your instructions. Thank you for your help.
@Stephanie_A OK so after turning the printer on again and homing everything my Z position was 0.7mm below the probe as it should be. I ran the M501 and here are the results.
I checked the firmware and the eeprom is active as far as that is concerned ( // comments removed) But if you look at the bottom of this image it states eeprom disabled, Is that part of my problem?
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Yep, so the currently flashed firmware doesn’t have the eeprom enabled.
Find the line with EEPROM_SETTINGS and uncomment it.
Also i think your m851 should be negative.
This is what my firmware is saying should I comment out the #if Enabled(eeprom settings) and eeprom chitchat part?
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No, you need to remove the // before #define EEPROM_SETTINGS
@Stephanie_A ok so I uncommented the eeprom and have now got the nozzle at the correct height, If I run G0 X100 Y100 Z0 the head moves to the centre or there abouts and settles the head at the required height.
BUT when I try to run a job through it, it goes back to how it was with an increased height of about 2mm. I stopped the print and homed everything then ran the same G0 X100 Y100 X0 and once again it positioned itself exactly as before.
M851 gives the correct probe offset of 0.75 so I am at a loss. is there anything else can I try?
Sorry also making it a negative number forces the nozzle right into the bed.
With eeprom settings, you configure m851, then do m500 to save it. Don’t put it in your start gcode.
After saving it, run the commands: G28 and then G29.
Then send M114 this will tell you the current position, which should be z0 after G29.
Always do it in this order when setting the z offset.
M851
M500
G28
G29
the distance the nozzle is above the bed must be subtracted from the m851 number. If its 2mm above the bed, and the m851 is set to 0.7 then you subtract 2mm, so 0.7-2 = -1.3
Your start gcode should also have g28 then g29 in it.
@Stephanie_A I have run the codes in that order but my z position finished at Z 8.85 now I’m sure that’s not right but for some reason it lifts back up higher than Z0.
Ok, then there is probably a raise after probing enabled. Just do a g1 z0 move after the g29 to check the offset.
Thank you Stephanie I will try this when I get home tonight, can I remove the raise in the firmware once everything is set up?
You would need to search for the setting. It’s fine if it stays enabled, you can just ad a g1 move after the g29 in the start code.
Also If you’re not using the latest marlin, I would recommend switching. It fixes a few things with bed levelling.
@Stephanie_A OMG I’m losing the will to live. Even after running G1 Z0 with the offset of .75 the nozzle ended up 1.4mm above where I need it.
I added the 1.4 to the .75 and reset the offset to 2.15 thinking this would get me where I need to be. Again the nozzle ended up 1.4mm above where it needed to be.
@Thomas_Sanladerer HHHEEEEEELLLLLPPPPP you put this idea in my head, where are when I need you.lol
some info I have found says to use Z max pin and not the Z min would this be correct?
You need to subtract, not add.
So after another few hours of chasing around I decided to flash the firmware from Tom’s web page again and this time run all your suggested codes and some amazing reason I’ve now ended up with a -0.74 offset and a machine that is actually printing.
Firstly thank you @Stephanie_A for all your help.
Secondly I can still say I have no idea why I was getting the problems that I had.