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Z-live adjust problems and bent bed on mk2s  

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jussi.p
(@jussi-p)
Active Member
Z-live adjust problems and bent bed on mk2s

Hi

I did xyz-calibration and trying to set z-live adjust. I don't have PLA, so I can't do that first layer calibration on menu. I downloaded these calibration squares https://www.thingiverse.com/thing:2547473 and first print I set z-live to -0.580 which was fine but when doing second print I have to set z-lve to -1.160, third -1.74 and so on. Why this happen and how to solve it? Can I run v2calibration with PETG?

Second problem is bent bed. It's OK on y-direction but on x-direction sides are lower than center. Bed was fine about month ago when I bought kit. Is this faulty bed and maybe warranty case? First layer won't print correct because of height difference and bed levelling won't correct it. Too much maybe?

The I'd like know more about mesh bed leveling. When printer do this, is it like setting z to "zero" value? If so this can be different every time? PINDAs temperature can affect this? If I change bed to aluminium one does this feature or PINDA work anymore?

Postato : 14/01/2018 12:27 pm
JeffJordan
(@jeffjordan)
Utenti Moderator
Re: Z-live adjust problems and bent bed on mk2s

Hi jussi.p,
I would recommend that you read these two threads here and here.
🙄 Ok, it's much to read... but it's worth it !

💡 and by the way: the p.i.n.d.a. is highly temperature sensitive, that's why you get different results for the live z adjustment after previously completed prints (which heat up the probe).
➡ there are several -more or less successful- workarounds for that problem. but at least an effective solution is to measure the temperature of the probe and take that into account for the height calculation. that's why the prusa i3 MK3 has such a new p.i.n.d.a 2 probe.

dem inscheniör is' nix zu schwör...

Postato : 14/01/2018 12:39 pm
jussi.p
(@jussi-p)
Active Member
Topic starter answered:
Re: Z-live adjust problems and bent bed on mk2s

Those calibrations what I was doing, I left printer cooling down between runs like around 30C both values. That z-live adjustment value was always same +previous runs values, like run 3 I had to set 3*-0,58, fourth 4*-0.58 and so on.

Postato : 14/01/2018 12:51 pm
JeffJordan
(@jeffjordan)
Utenti Moderator
Re: Z-live adjust problems and bent bed on mk2s

???
check your starting script inside your slicer.
make sure that you use absolute coordinates (not relative), forced by G90 and a mesh bed levelling (G80) inside it.
and don't set any z-offset inside your slicer ! the live z adjustment has to be done at the printer's menu.

dem inscheniör is' nix zu schwör...

Postato : 14/01/2018 1:45 pm
jussi.p
(@jussi-p)
Active Member
Topic starter answered:
Re: Z-live adjust problems and bent bed on mk2s

I use slic3r prusa edition and nothing is changed from defaults. I haven't set any z adjustments in slicer, only in printer menu. First run after xyz-cal. proper z-adj. was -0.58, then after cooldown second run z-adj. was -0.58 and I had to put -0.58 more, so proper setting was -1.16, third run after cooldown 3*-0.58 and so on.

Can this happen if the first layer cal. is not run? (no pla, cant run it)

Postato : 14/01/2018 1:56 pm
jussi.p
(@jussi-p)
Active Member
Topic starter answered:
Re: Z-live adjust problems and bent bed on mk2s

I did run that first layer calibration without filament and now it's working.

If PINDA is so temperature sensitive, why starting procedure is not 1. mesh bed levelling 2. warming up etc..?

Postato : 14/01/2018 5:03 pm
JeffJordan
(@jeffjordan)
Utenti Moderator
Re: Z-live adjust problems and bent bed on mk2s

if the printer hasn't printed at least once a calibration gcode containing the G87 command, it ignores at the start of a new print any z-live adjustment value. so if you start a new print and previously tuned in the first layer to 580µm, you still got the value in the memory, but the G80 meshbed levelling resets the printers "view of the world" to 0.... so you need to add 580µm again to the value.

dem inscheniör is' nix zu schwör...

Postato : 14/01/2018 6:35 pm
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