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Very poor layer-to-layer alignment  

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Gunter
(@gunter-2)
Active Member
Very poor layer-to-layer alignment

Hi,

I just finished assembling my Prusa i3 kit I got last week.

Yesterday I first printed the "PLA_Prusa_200um_30M" sample. After that I printed a part designed myself, higher in z-direction. Here one could easily see a very poor layer-to-layer alignment. I reduced the speed to 90%, resulting in better, with 80% in fair quality. [see: 'Silent_100_90_80']
Having a closer look at the 'Prusa' (silent 100%) it shows the same issue for the baseplate, and later in print for 'U' and 'S'. [see: 'Prusa_U']

Following the recommendation in this forum, I tried again today, same g-code in High-power mode: Result is a disaster and I stopped printing! [see: 'High_100']
And now the bad news: Going back to yesterdays settings, Silent-mode, 90% is not better and far from what I got yesterday.
Remarkably, today even the frame, printed on the bed at the beginning is not equally spaced in y-direction, as it was yesterday!

The pictures should show the issue.

Question 1: What may have caused the misalignments at the first prints, which was about the same in x- and y-direction?
Question 2: What made it worse today, especially in y-direction?

Thanks for any advise
Gunter

Posted : 17/05/2016 7:59 pm
Josef Průša
(@josef-prusa)
Member Admin
Re: Very poor layer-to-layer alignment

Check if your belt pulleys are tight enough on the motor shafts 🙂

Founder and owner / Majitel a zakladatel
Posted : 17/05/2016 8:04 pm
Gunter
(@gunter-2)
Active Member
Topic starter answered:
Re: Very poor layer-to-layer alignment

I'm sure I double-checked during assambly, but I will do again.

Currently printing the part once more, afer 'switching off - reconnecting power-cord to PSU - switching on'. There might have been a bad connection there.

With "good" settings: silent-mode, 90%, frame on bed is now better, but still not as good as yesterday, the print also looks better than the three stopped runs before. ~15min to go.

Regards
Gunter

Posted : 17/05/2016 8:31 pm
Gunter
(@gunter-2)
Active Member
Topic starter answered:
Re: Very poor layer-to-layer alignment

Print is finished: result is good for the upper part, but the fist 6mm (T-shape foot) still looks as distorted as in the posted image Silent_100_90_80.jpg, even so it was printed with only 90%!
I would say I'm back where I was yersterday.

I fastened the belt pulleys a little bit more, with a new hex-spanner - tolerance is critical with this very little srews - now printing a smaller test-structure.

I'll give an update tomorrow.

By Gunter

Posted : 17/05/2016 9:29 pm
Gunter
(@gunter-2)
Active Member
Topic starter answered:
Re: Very poor layer-to-layer alignment

Solved!

The belt pulleys were not tight enough on the motor shafts!

May be one should check the pulleys screws after the first hour of printing, as they might loosen in case they were not fastened tight enough.
I will keep an eye on that in the future.

Now I get very good results at 100% speed, and can't see any difference between silent- and high-power-mode. 😀

Thank you Josef for your advise and of course for your work on printer development - it's a great tool!

Gunter

Posted : 18/05/2016 7:28 pm
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