v2calibration.gcode and "live adjust z"?  

Re: v2calibration.gcode and "live adjust z"?

There are two special g-code commands that are in the V2calibration.gcode file: G87 and G88. See my post from a couple of days ago here.

I still don't understand exactly what they do, but it seems that G88 just turns off the "your printer hasn't yet been calibrated" message. G87 has something to do with the 'live adjust Z', but I don't understand exactly how it works. Even with that post of mine, I still haven't figured out what is wrong with the live Z adjust, I've been having problems very similar to yours. I'll adjust the Z height during a print, but during the next one it's way too high or low, as if it was never adjusted. It's really frustrating and I don't know what to do about it.

Re: v2calibration.gcode and "live adjust z"?

There are two special g-code commands that are in the V2calibration.gcode file: G87 and G88. See my post from a couple of days ago here.

I still don't understand exactly what they do, but it seems that G88 just turns off the "your printer hasn't yet been calibrated" message. G87 has something to do with the 'live adjust Z', but I don't understand exactly how it works. Even with that post of mine, I still haven't figured out what is wrong with the live Z adjust, I've been having problems very similar to yours. I'll adjust the Z height during a print, but during the next one it's way too high or low, as if it was never adjusted. It's really frustrating and I don't know what to do about it.

Have you raised an issue in their firmware github for clarification of these?

I'm guessing that the G88 is to "really" set the z-offset only during printing. I briefly read about your original post on your link above, from my understanding was that the z offset didn't get saved into eeprom, more like the live z adjust feature is just a volatile variable/value, while either g87 or g88 will save it to the rambo mini's eeprom based on how many adjustment were made.

in fact, at the start of the printing (based on my own theory how they designed the firmware), is that the printer will always load from the eeprom's z-offset.

For example of not having the g87/g88 assumed

at start of print
load z-offset
nozzle too high = use live z adjust
live z adjust value saved <= e.g -0.4mm
end of print

Then theoretically at the next print where the printer still on and never powered off

at start of print
load z-offset <= still 0
during print the nozzle still far as if never changed
change live z adjust <= -0.4mm retained and changed to -0.8mm to reach closer to the bed
end of print

Unless the are either G87/G88 at the start/end of the gcode script, the live z adjust variable will always be volatile and never get saved to the "proper/real" z-offset eeprom value. Technically speaking, both are different variable to begin with.

I always adjust the z-offset by going to "babystepping z" on marlin, then go to "setting > motion > z-offset" set it to according how many offset you put on babystepping, click, then "go back > store memory"

Since there is a new firmware available 3.0.10; having eeprom enabled, I'm going to take a look into what variable they have for eeproms

Re: v2calibration.gcode and "live adjust z"?

Sarf2k4, thanks for explaining that to me. So since I like to use other prints (like the 1st layer of the PRUSA logo or the batman logo) to lock in my z height, would it be best for me to just add G87 and G88 to my custom start g-code?

Also, what about adjusting the 'live adjust z' in Settings->Live Adjust Z when it's not printing? Same thing, it doesn't save it to the eeprom?

Re: v2calibration.gcode and "live adjust z"?

Sarf2k4, thanks for explaining that to me. So since I like to use other prints (like the 1st layer of the PRUSA logo or the batman logo) to lock in my z height, would it be best for me to just add G87 and G88 to my custom start g-code?

Also, what about adjusting the 'live adjust z' in Settings->Live Adjust Z when it's not printing? Same thing, it doesn't save it to the eeprom?
The v2calibration.gcode file is also listed in this link http://www.prusa3d.com/drivers/

I'm guessing that you could, just follow what is it that unusual from v2calibration.gcode, but having these into each print might do more harm than good. Maybe you can try and see how with the prusa logo and batman gcode supplied and see how the z-offset goes.

live z adjust from the setting does change the z axis position but i also don't think that it will be saved to the eeprom, I kind of don't dare to test this as I've ruined my platform slightly just for the very first day after the mk2 has been assembled.

Re: v2calibration.gcode and "live adjust z"?

The v2calibration.gcode file is also listed in this link http://www.prusa3d.com/drivers/

I'm guessing that you could, just follow what is it that unusual from v2calibration.gcode, but having these into each print might do more harm than good. Maybe you can try and see how with the prusa logo and batman gcode supplied and see how the z-offset goes.

live z adjust from the setting does change the z axis position but i also don't think that it will be saved to the eeprom, I kind of don't dare to test this as I've ruined my platform slightly just for the very first day after the mk2 has been assembled.

Well, one reason I use other prints to lock in the z-height is because I've found V2calibration can only get me in the general ballpark - I need to see how it's space-filling the first layer for me to really lock it in to the best value. So your recommended method would be the following?


1. Run V2calibration.gcode, get in the general vicinity of the correct z height.
2. Run another print (PRUSA logo, etc.) to check first layer filling.
3. Make adjustment to z-height and re-run V2calibration.
4. Re-run other print to check first layer filling
5. Redo steps 3-4 until satisfactory.


Also, is there any way I can see what the current actual z-height adjustment is, both the volatile temporary one and the permanent one written to the eeprom? Maybe some command if I'm connected via pronterface or something?

Re: v2calibration.gcode and "live adjust z"?

The special Gcode needs to only be issued once.

It is not necessary to use it every time you change the Z adjust value.

What I do after a calibration is run v2calibration.gcode then print squares (similar to JeffJordan's method) to tune the Z offset.

If you use JeffJordan's Gcode you can skip the v2calibration part as it contains the two Gcode commands.

Re: v2calibration.gcode and "live adjust z"?

The special Gcode needs to only be issued once.

It is not necessary to use it every time you change the Z adjust value.

What I do after a calibration is run v2calibration.gcode then print squares (similar to JeffJordan's method) to tune the Z offset.

If you use JeffJordan's Gcode you can skip the v2calibration part as it contains the two Gcode commands.

Well, something is wrong, because when I change the Z adjust value it isn't permanent.

Re: v2calibration.gcode and "live adjust z"?

Well, something is wrong, because when I change the Z adjust value it isn't permanent.

After doing a bit more research, I am also considering another possibility: could it be that my PINDA probe is malfunctioning and needs to be replaced?

Re: v2calibration.gcode and "live adjust z"?

Basically after reset xyz calibration data, we had to issue the special gcode again? G87/G88?

If your pinda probe has problem, maybe you could consider checking on the pinda height placement first, besides, it can do mesh leveling is it not?

I guess you could try to reset the calibration data from calibration menu, or do a full reset from 3d printing handbook and redo all the calibration, this time properly.

From my understanding of the code also, if the calibration hasn't been set nor z-offset as well, without issuing the g87/88, eeprom might as well disabled for z-offset values.

I have another off-topic question, G80 is a mesh bed leveling procedure, at the start of the gcode, there is one but there are no command to tell the printer to go to z0. Does this mean that the G80 will instruct the printer to go home position at z0 after it has done mesh bed leveling?

Re: v2calibration.gcode and "live adjust z"?

Basically after reset xyz calibration data, we had to issue the special gcode again? G87/G88?
➡ yes.

...If your pinda probe has problem, maybe you could consider checking on the pinda height placement first, besides, it can do mesh leveling is it not?

just to let you know: whith my "mk2 spare part printer project" i have issues with a brand-new genuine pinda probe from prusa:
it's nearly completely deaf.
it even doesn't trigger when i put it directly at the printbed. only where the calibration points are (and the screws for the bolts), it'll trigger... and there only at approximately 0.4mm height :?.
the pinda at my running mk2 is much more sensitive and able to operate as an endstop 0.8mm above the printbed (which means that it's able to trigger everywhere over the printbed).

Re: v2calibration.gcode and "live adjust z"?

Basically after reset xyz calibration data, we had to issue the special gcode again? G87/G88?
➡ yes.

...If your pinda probe has problem, maybe you could consider checking on the pinda height placement first, besides, it can do mesh leveling is it not?

just to let you know: whith my "mk2 spare part printer project" i have issues with a brand-new genuine pinda probe from prusa:
it's nearly completely deaf.
it even doesn't trigger when i put it directly at the printbed. only where the calibration points are (and the screws for the bolts), it'll trigger... and there only at approximately 0.4mm height :?.
the pinda at my running mk2 is much more sensitive and able to operate as an endstop 0.8mm above the printbed (which means that it's able to trigger everywhere over the printbed).

Wow, at 0.8mm above the printbed? wouldn't that kind of too close to the bed already especially the pinda being too low hitting the curled object and nozzle might destroying the print surface during probe?

Re: v2calibration.gcode and "live adjust z"?

Firstly, G88 is no longer used. It was in the early firmwares, but I can't remember what for. I think there are some posts about its use.

G87 is the gode which basically turns off the calibration message:

/**
* G87: Prusa3D specific: Enable babystep correction after home
* This G-code will be performed at the end of a calibration script.
*/
case 87:
calibration_status_store(CALIBRATION_STATUS_CALIBRATED);
break;

/**
* G88: Prusa3D specific: Don't know what it is for, it is in V2Calibration.gcode
*/
case 88:
break;

G87 can be issued whenever you want; from Octoprint, Pronterface or simply included in the Start GCode of any/all files.

With regard to the probe height, ideally the probe should be about 1mm higher than the nozzle, but this is not always possible. Again the method used to get to this position is well documented in older posts, but goes something like this:

Print a set of 9 calibration squares (see attached) and adjust Live Z to get the centre square correct. The use bed level adjustment to set the remainder. Issue a G87.

Note that a sheet of copy paper is about 0.1mm thick, but feeler gauges are preferable.

Peter.

Re: v2calibration.gcode and "live adjust z"?

I heard feeler gauge are good but it is so smooth until unable to feel the nozzle if it really hits the feeler gauge.

I sometimes/often use brim as an indication. When the part with brim enabled has finished printing, I take my trusty digital caliper and measure the brim thickness

Re: v2calibration.gcode and "live adjust z"?

Just raised a question about these 'unknown' gcodes, can do some reading here
https://github.com/prusa3d/Prusa-Firmware/issues/61