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First Layer Calibration. -1.800 still not enough?  

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weust
(@weust)
Active Member
First Layer Calibration. -1.800 still not enough?

I got my Mini+ in today (pre-assembled) and after setting it up I'm now at the wizard.
For hours now.

When doing the first layer calibration I am now down to -1.800 and it's still not low enough.
The text pattern at the end (the square part) looks even but there are still gaps between the lines.

The max is -2.000, but it can't be right to have to go that low? If that is even enough in my case.

I test the SuperPINDA and it seems to work fine as far as I can tell using the guide.

Posted : 28/07/2021 3:54 pm
BogdanH
(@bogdanh)
Reputable Member

Move SuperPINDA sensor up for about 0,5-1,0mm (so vertical distance between SuperPINDA and tip of the nozzle is about 1,5mm). After that make fresh First layer calibration (starting with 0 Z-offset).

Mini+ with Bondtech upgrade & modified firmware...
Posted : 28/07/2021 4:02 pm
weust
(@weust)
Active Member
Topic starter answered:
.

Alright. I will try that later tonight.

Posted : 28/07/2021 4:19 pm
JMH714
(@jmh714)
Estimable Member
This title left blank on purpose.

If you have zip tie that Prusa gave you (I don't know if it included in semi-assembled kit, I had kit assembly), you can put it under SuperPINDA as shown in kit assembly manual - first step: https://help.prusa3d.com/en/guide/7-preflight-check_204705

That will help you adjust SuperPINDA better.  

Posted : 29/07/2021 12:34 am
jsw
 jsw
(@jsw)
Noble Member

What I've found when tweaking the Pinda position is that over the months the threads of the Pinda have become impressed in the ring assembly which holds the Pinda, and therefore it will tend to settle into one of those threads.

For a fine tweak, loosening the Pinda and rotating it will give you much finer and more precise control.  You can get in in the ballpark with a mechanical adjustment, and then fine-tuned for each (type of) sheet with the Z calibration.

Posted : 29/07/2021 12:39 am
BogdanH
(@bogdanh)
Reputable Member

@JMH714
That tutorial should be updated a while ago, because zip tie is too thin and doesn't work for SuperPINDA (is meant for old PINDA only). Even Prusa support staff now says SuperPINDA must be higher.

@jsw
I noticed that too. And knowing that thread pitch is 1mm, it's easy to make fine adjustment by rotating SuperPINDA (i.e. half rotation is 0,5mm).

Mini+ with Bondtech upgrade & modified firmware...
Posted : 29/07/2021 7:44 am
AndrewTerry
(@andrewterry)
Eminent Member
SuperPINDA wires?

@jsw @BogdanH -  when rotating the sPINDA, I get worried about the wires breaking... the last time I did mine I ended up loosening the screws to the point where I could move it up and down without rotating. Are the wires/connections fairly robust, or is there a knack to rotating it without twisting the wires too much?

Posted : 29/07/2021 8:57 am
cwbullet
(@cwbullet)
Illustrious Member
robust

 

Posted by: @andrewterry

@jsw @BogdanH -  when rotating the sPINDA, I get worried about the wires breaking... the last time I did mine I ended up loosening the screws to the point where I could move it up and down without rotating. Are the wires/connections fairly robust, or is there a knack to rotating it without twisting the wires too much?

I have not heard any issues on the forum or had any issues with my SPINDAs or PINDAs with wires breaking.  I think they are fairly robust. 

--------------------
Chuck H
3D Printer Review Blog...
Posted : 29/07/2021 9:21 am
weust
(@weust)
Active Member
Topic starter answered:
Because I need to fill the Title with something

So if a zip tie thickness isn't right anymore, what is?

Didn't get to calibrating last night anymore. Was too dark and I was too tired.

Posted : 29/07/2021 11:10 am
BogdanH
(@bogdanh)
Reputable Member

@AndrewTerry -Agree, but it's not about screwing PINDA all the way. We still need to loose the assembly ring to insert PINDA and make rough adjustment. After that we just slightly tighten the screw (so PINDA can't move up/down freely). Now we move print head down until tip of the nozzle touches the print sheet and then we precise measure distance between bottom of PINDA and print sheet.
Usually that distance won't be exactly 1,5mm (which is recommended distance). Let's say the distance is 0,8mm (zip tie thickness)... means, we need to increase distance by about 0,7mm. We can do that easily by rotating PINDA somewhere between half and full turn and then tighten the screw on ring to fix PINDA.
That is, by rotating PINDA only up to one full turn doesn't twist wires much.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 29/07/2021 12:16 pm
weust
(@weust)
Active Member
Topic starter answered:
.

Adjusted the SuperPINDA and did the first layer calibration. It's printing benchy now.

15% in and it's looking alright as far as I can tell.

Posted : 29/07/2021 7:32 pm
Piasecznik
(@piasecznik)
Active Member
-1850 for me

My Mini+ 1st level calibration ended up on -1850 and I found that looking from the top at Z axis leadscrew, it turns counterclockwise when nozzle travels left and clockwise when right printing same layer. Indicating left side of the bed is lower than right side. It is not much, probably less than 1 turn for whole bed. Would you recommend to make X axis skew adjustment? I printed 1 layer test circle print from thingiverse and it is perfect. I just dont want to ruin perfect results I'm getting just for sake of having square bed if autoleveling can compensate it so well.

Posted : 29/07/2021 9:48 pm
weust
(@weust)
Active Member
Topic starter answered:
.

If it prints alright I would not change it.
In my case, yesterday, I noticed the First Layer Calibration was very high on the left side while the nozzle was almost touching the bed on the right side.
So I loosened the three screws of the XZ part and pushed it in before tightening the screws again. That seemed to have helped.

The benchy finished about 20 minutes ago and looks very nice. Little bit of stringing, nothing major.
Will post a photo tomorrow.

Posted : 29/07/2021 10:23 pm
JMH714
(@jmh714)
Estimable Member
Please fill out this field.

 

Posted by: @bogdanh

@JMH714
That tutorial should be updated a while ago, because zip tie is too thin and doesn't work for SuperPINDA (is meant for old PINDA only). Even Prusa support staff now says SuperPINDA must be higher.

@jsw
I noticed that too. And knowing that thread pitch is 1mm, it's easy to make fine adjustment by rotating SuperPINDA (i.e. half rotation is 0,5mm).

Umm... I did it when I assembled together and my new Mini+ is working just exactly like my two MK3S+. 

Posted : 01/08/2021 2:24 pm
BogdanH
(@bogdanh)
Reputable Member

 

Posted by: @jmh714

Umm... I did it when I assembled together and my new Mini+ is working just exactly like my two MK3S+. 

Of course it works with zip tie (0,8mm) too.
But you probably noticed in this forum, that many new owners have troubles with first layer calibration because approaching negative Z-offset limit of -2.000mm.
Let's say user makes first layer calibration, where first layer stick fine at Z-offset of -1.800. But when user changes to (thinner) textured sheet, he isn't able to make successful first layer calibration anymore -because he hits Z-offset limit and thus can't go lower.

One can easily find out the "perfect" SuperPINDA height position by manually (by hand) moving print head down. In my case, LED on SuperPINDA goes off, when distance between print sheet and bottom of SuperPINDA is about 2.3mm. Now imagine I adjust PINDA height to 0,8mm. That means, my "perfect" first layer will be at Z-offset of about (2.30 - 0.80=) -1.5mm. That is, my usable range can only be between -1.5 and -2.00mm. Things that could make this even narrower are: PINDA's sensitivity tolerances, nozzle height and sheet thickness. And thus, I'm not surprised reading that someone hits -2.00 Z-offset limit and first layer still isn't "right".
If we start with PINDA height of 1.5mm, we will land with first layer Z-offset at about (2.30-1.5=) -0.80, which is nicely in the middle of adjustment range. Means, in future, we will be able to re-adjust Z-offset without troubles in case we change nozzle or print sheet.

Mini+ with Bondtech upgrade & modified firmware...
Posted : 01/08/2021 5:43 pm
Ringarn67 liked
JMH714
(@jmh714)
Estimable Member
Please fill out this field

 

Posted by: @bogdanh

 

Posted by: @jmh714

Umm... I did it when I assembled together and my new Mini+ is working just exactly like my two MK3S+. 

Of course it works with zip tie (0,8mm) too.
But you probably noticed in this forum, that many new owners have troubles with first layer calibration because approaching negative Z-offset limit of -2.000mm.
Let's say user makes first layer calibration, where first layer stick fine at Z-offset of -1.800. But when user changes to (thinner) textured sheet, he isn't able to make successful first layer calibration anymore -because he hits Z-offset limit and thus can't go lower.

One can easily find out the "perfect" SuperPINDA height position by manually (by hand) moving print head down. In my case, LED on SuperPINDA goes off, when distance between print sheet and bottom of SuperPINDA is about 2.3mm. Now imagine I adjust PINDA height to 0,8mm. That means, my "perfect" first layer will be at Z-offset of about (2.30 - 0.80=) -1.5mm. That is, my usable range can only be between -1.5 and -2.00mm. Things that could make this even narrower are: PINDA's sensitivity tolerances, nozzle height and sheet thickness. And thus, I'm not surprised reading that someone hits -2.00 Z-offset limit and first layer still isn't "right".
If we start with PINDA height of 1.5mm, we will land with first layer Z-offset at about (2.30-1.5=) -0.80, which is nicely in the middle of adjustment range. Means, in future, we will be able to re-adjust Z-offset without troubles in case we change nozzle or print sheet.

Ahh, gotcha. 👍 

Posted : 02/08/2021 2:40 am
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