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First layer, bed uneven?  

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bryan.r
(@bryan-r)
Eminent Member
First layer, bed uneven?

I have had my MK2 built and running for at least a week and a half. I have had quite a few really great prints so far.
I've noticed that my last couple prints it seems to have an uneven "smooshing" on the first layer? I have done the XYZ Calibration twice and everything has gone perfect with that with no issues - calibration has gone perfect from the start, no adjustments needed to the build.
I have run the Calibration.gcode a few times, being sure I get my "smooshing" as optimum as possible - I am currently at -.662mm for my live adjustment.
Hopefully you can tell from the photo(Vase print from the SD card) what I am talking about, and from the drawing. The drawing shows that in the circle (looking at the print from the top) about the top half(#1 in photo) seems to be noticeably more smooshed than that bottom half(#2 in photo) - going straight down from the bottom half is going towards the front of the printer.
Any ideas as to why? I was under the impression that the Mesh Calibration was supposed to handle this by compensating for any "un-levelness" of the bed with the 9 points?
As I said, calibration succeeds, PINDA is secure and level, smoosh factor appears appropriate.
It not a huge issue but it just seems like something that shouldn't be happening. Is this kind of standard/normal and I am just being too picky?
Thanks for any ideas or advice!

Posted : 08/10/2016 12:07 am
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: First layer, bed uneven?

Bryan

In the calibration menu, there is an option (which I can't remember what it's called) to adjust the bed level. This allows a +- 50 micron adjustment of the bed (front/rear/left/right) to compensate for any manufacturing tolerances in the probe points, which is exactly what you are seeing.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 08/10/2016 9:31 am
bryan.r
(@bryan-r)
Eminent Member
Topic starter answered:
Re: First layer, bed uneven?

Awesome! That sounds like exactly what I need. Thanks so much!

Posted : 08/10/2016 7:33 pm
bryan.r
(@bryan-r)
Eminent Member
Topic starter answered:
Re: First layer, bed uneven?

Finally getting back to an update with this, been away with work.
So as I mentioned in my original post I have not had any issues with successfully calibrating XYZ, mesh bed leveling, etc.. I have not had issues with first layer adhesion. This was more just a quest to get my first layer as smooth, even, and perfect as possible and not have any of those rough patches on one side, etc.
So as Peter had suggested, I started playing with adjusting the bed level parameters.
After many test prints(just using a simple square that is 75mm x 75mm) I finally have a pretty smooth consistent looking first layer.
These are the settings I have ended up with at this point:
Live adjustment : -.630mm
Bed Rear : -29
Bed Left : -5
Bed Front : 30

I'm just curious, is this at all out of the norm?
Has anyone else had to do similar settings to get it perfect?

Thanks!

Posted : 21/10/2016 7:35 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: First layer, bed uneven?

Bryan

The small adjustments for front/back/left/right allow for differences in the copper pads used by the probe for detecting the bed. Your need to make the adjustments are not unusual.

The live adjustment value is a bit higher than I would expect which indicates that you probe is a tad low (my live z is around -0.14mm).

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 21/10/2016 8:26 pm
bryan.r
(@bryan-r)
Eminent Member
Topic starter answered:
Re: First layer, bed uneven?

Ok, thanks a lot for the feedback!
I was pretty careful to set the probe the way mentioned in the instructions - with the end of the probe case in line with the tip of the wiring hook.
I guess I could take a look at maybe moving it up a little - because if that setting seems a little too low to you it gets me worried about it maybe eventually catching on something. I have eye-balled it several times when it is doing the first layer and it at least "seems" to be approx 1mm higher than the nozzle - but I haven't had my eyeballs calibrated recently! 🙂
Thanks again! I feel better about those bed level settings now at least!

Posted : 21/10/2016 9:49 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: First layer, bed uneven?

About 0.75 to 1mm higher than the nozzle is good. Best leave it alone.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 21/10/2016 10:02 pm
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