<p>Long story short: <strong>Try to replace the stock power supply.</strong></p>

<ul>
<li>We connected UPS between the printer supply and the wall outlet and the skips reduced to one/two per print.</li>
<li>We replaced the supply with random old used <code>Mean Well SP-320</code> (zero care about the power panic feature, just plain 24V connected) and voilà: reference design passed.</li>
<li>Also few more complex designs after supply switch are still flawless, so we hope that was the problem and it's fixed now.</li>
<li>This Q&amp;A post is to help others to skip the major frustration and save some time.</li>
</ul>

CC BY-SA 4.0
2019-11-23T22:42:01.473Z
2019-11-24T08:06:09.650Z
2019-11-24T08:06:09.650Z
sharpener
<p>After approx. a year of more or less problem-free printing (40 days print time) with Prusa i3 mk3 kit, we started to suffer the random layer shifting on Y axis.</p>

<ul>
<li>We inspected all the motor connectors are properly inserted in the mainboard and the wires are intact.</li>
<li>We ensured all the pulleys' screws on the x/y motor shafts are very tight and secure to be sure the pulleys don't slip.</li>
<li>We inspected the belts and pulleys, there is no mechanical problem like dust blobs, filament residues, etc.</li>
<li>We tightened the belts to be hard enough to show the expected <code>support|belt status</code> value (under 280) after <code>self test</code> is performed.</li>
<li>We switched off the <code>crash detection</code> feature.</li>
<li>We fully cleaned/re-lubricated the Y axis linear bearings and the rods to be sure there is no dirt causing any friction.</li>
<li>We tightened the nuts on the U holders fixing the bearings to the bed (hard enough not to squeeze the bearings so they can freely move on the rods).</li>
<li>We bought Japan <code>PNY LM8UU</code> bearings and replaced the original ones on Y axis (suspecting they are worn out).</li>
</ul>

<p>Nothing of these helped fully:</p>

<ul>
<li>Some steps improved the quality (like only one random skip in print).</li>
<li>Some steps degraded the quality (like additional step skips in previously flawless X axis).</li>
</ul>

<p>Since the issues started, we had 4 hour reference design to be printed again and again using the same setup/filament etc. It became reference because its print started to exhibit the skips. We refused to slow down the print or perform any other workarounds, because we wanted to <code>make the printer great again</code> ;-)</p>

<p><strong>What else should have been done to revert back to flawless prints without random X/Y step skipping and thus layer shifting?</strong></p>

<prusa-i3><layer-shifting>
Prusa i3 mk3 step skipping and layer shifting
sharpener
# Prusa i3 mk3 step skipping and layer shifting

(Asked by: username_0 on 2019-11-23)

After approx. a year of more or less problem-free printing (40 days print time) with Prusa i3 mk3 kit, we started to suffer the random layer shifting on Y axis.

* We inspected all the motor connectors are properly inserted in the mainboard and the wires are intact.
* We ensured all the pulleys' screws on the x/y motor shafts are very tight and secure to be sure the pulleys don't slip.
* We inspected the belts and pulleys, there is no mechanical problem like dust blobs, filament residues, etc.
* We tightened the belts to be hard enough to show the expected `support|belt status` value (under 280) after `self test` is performed.
* We switched off the `crash detection` feature.
* We fully cleaned/re-lubricated the Y axis linear bearings and the rods to be sure there is no dirt causing any friction.
* We tightened the nuts on the U holders fixing the bearings to the bed (hard enough not to squeeze the bearings so they can freely move on the rods).
* We bought Japan `PNY LM8UU` bearings and replaced the original ones on Y axis (suspecting they are worn out).

Nothing of these helped fully:

* Some steps improved the quality (like only one random skip in print).
* Some steps degraded the quality (like additional step skips in previously flawless X axis).

Since the issues started, we had 4 hour reference design to be printed again and again using the same setup/filament etc. It became reference because its print started to exhibit the skips. We refused to slow down the print or perform any other workarounds, because we wanted to `make the printer great again` ;-)

**What else should have been done to revert back to flawless prints without random X/Y step skipping and thus layer shifting?**

**Tags:** prusa-i3, layer-shifting

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## 1 answers

### Answer by username_0 on 2019-11-23. Score: 2

Long story short: **Try to replace the stock power supply.**

* We connected UPS between the printer supply and the wall outlet and the skips reduced to one/two per print.
* We replaced the supply with random old used `Mean Well SP-320` (zero care about the power panic feature, just plain 24V connected) and voilà: reference design passed.
* Also few more complex designs after supply switch are still flawless, so we hope that was the problem and it's fixed now.
* This Q&A post is to help others to skip the major frustration and save some time.


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