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Impossible to calibrate Z axis  

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claude.g2
(@claude-g2)
Eminent Member
Impossible to calibrate Z axis

Hi,

Everything was working fine until I load the new firmware 3.1.10. After loading that new version I started a re-calibration test sequence :

1 / selftest : OK

2 / XYZ test : the nozzle is clean

- The first sequence (4 points) is OK, the Z carriage touches the end stoppers ( rattlling sound ) and the nozzle never touches the sheet of paper.

- The second sequence (9 points) fails : point 1, the nozzle touch the bed a little bit, point 2 and 3 are ok ( no touch) but point 4 a big touch of the bed occurs ( move of 1 or 2 mm )
If I re-start a Z or XYZ calibration sequence, I can see that one stop of the Y carriage arrives ~2 mmm before the second one ( due to the last touch )
The same problem occurs sequence 9 points fails again.

It sems that the Z informations are lost between the two calibration sequences ( 4 points and 9 points ° . The bed is as it was previously, well fixed on the Y bars and horizontaL The PINDA is at the right place and well attached to its support and I manufactured several pieces yesterday without any problem ...

Thanks for help

Postato : 19/05/2017 7:07 pm
JeffJordan
(@jeffjordan)
Utenti Moderator
Re: Impossible to calibrate Z axis

what's your height distance between tip of the nozzle and tip of the p.i.n.d.a. probe ?
best would be about 0.7mm (the nozzle must be closer to the bed as the inductive probe).
-> rule of thumb: thickness of a credit card

dem inscheniör is' nix zu schwör...

Postato : 19/05/2017 7:49 pm
claude.g2
(@claude-g2)
Eminent Member
Topic starter answered:
Re: Impossible to calibrate Z axis

Hi again,
Thanks for reply

The distance nozzle / Pinda is d # 1 to 1,1 mm . Do you think that is too much ( wrt 0,7 mm) ?
I worked in that condition until now doing re-calibration sequence from time to time
The firmware updating can't be a possible explanation ?

Postato : 19/05/2017 8:53 pm
claude.g2
(@claude-g2)
Eminent Member
Topic starter answered:
Re: Impossible to calibrate Z axis

- I think that I understand why I got that problem of Z calibration.

- I just tried to re-ajusted the PINDA probe and found that its support was damaged and then not stable ( see image). When I look the design of this support I understand why I got the problem (too weak sections ). My probe has been may be damaged too during this operation !

-- I have seen that the present design of the extruder body has been modified in March and specially concerning the probe support ( i3 MK2 printed parts ),it seems to be the only alternative solution ( even if I don't know how to proceed in my case...) ?

- If my probe is damaged, where can I buy another one, I don't see this article in Prusa shop ?

- Any chances to get replacement parts from PRUSA ( model received in january ) ? )

Postato : 20/05/2017 3:04 pm
JeffJordan
(@jeffjordan)
Utenti Moderator
Re: Impossible to calibrate Z axis

...- If my probe is damaged, where can I buy another one, I don't see this article in Prusa shop ?

- Any chances to get replacement parts from PRUSA ( model received in january ) ? )

...

go to the prusa shop and contact the sales team through the chat.
aks them to enable you for the prusa spare parts section for customers.
usually they grant you access then to the prusa specific spare parts section, where you can buy such things like hobbed pulleys, p.i.n.d.a. probe, mk42 heatbed etc.
you can order printed spare parts (like the extruder body) as well...

dem inscheniör is' nix zu schwör...

Postato : 20/05/2017 5:05 pm
claude.g2
(@claude-g2)
Eminent Member
Topic starter answered:
Re: Impossible to calibrate Z axis

Hi,

- Thanks for informations

- I have checked my probe : the red led switches On/Off around 0,7 mm ( explaining my problem with damaged support and indicating that the distance of ~1mm was at the limit even if it was possible to make the calibration ). The bad news is that the it is mechanicaly damaged and I need to make some repair first and cut the cable to do so. Do you know the function of each of the three wires ? ( and for curiosity the electrical equivalent of this sensor ) ?

- In the mean time, I had a look to your post describing the improvments / modificatoions of your MK2, very impressive...
I noticed your remark related to the probe and its sensitivity to voltage supply. The Z calibration being essential, I intend to apply your modification to be on the safe side and not depend at short and long term of any aging effect ( at least with respect to this function) . If I undersood well a regulated power supply adjustable from ~3V to 5V is necessary ?

Postato : 20/05/2017 6:31 pm
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