<p>Embarassingly, I discovered that the cable to the heatbed was sometimes caught between the on/off switch and the adjacent power plug. So, for high Y values the cable was very tight and the bed could not be moved. Presumably the &quot;knocking&quot; came from the Y-axis motor. The problem was fixed by attaching this cable to the adjacent hotend/X axis motor cable.</p>
<p>Hopefully this will be helpful to others who have a similar problem. Please add a comment if you experienced this.</p>

CC BY-SA 4.0
2022-08-19T14:49:43.660Z
2022-08-19T20:36:02.390Z
2022-08-19T20:36:02.390Z
Lewis Baxter
<p>Your bed has become unleveled or skewed in Y direction.</p>
<p>When the nozzle is closer to the bed the extruder has to push harder to get the same filament flow through a smaller space, the stresses the extruder to a point that the stepper skips or grinds the filament. This is generally described as a knocking sound.</p>
<p>You need to find out why the bed is higher at the upper end of the Y range and fix this. Otherwise your bed has become warped and may need to be replaced. There are alternatives in using a sensor (e.g. a BLTouch) to sense the shape of the print surface, it will then automatically adjust for the shape during the first 10 mm (default value) of your print product. Installing a sensor requires new or alternative firmware.</p>

CC BY-SA 4.0
2022-08-13T13:27:01.193Z
Thanks Oscar. That is very helpful if there were only 2 scenarios. But, I found a third that suggests that closeness of nozzle to bed is not relevant.
Lewis Baxter
CC BY-SA 4.0
2022-08-12T14:43:48.580Z
2022-08-12T17:24:26.917Z
2022-08-12T17:24:26.917Z
0scar
<p>On my Ender 3 v2 printer I recently and consistently get some knocking.
This happens in only two scenarios.</p>
<p>First, it now occurs all the time when printing the initial test strip gets near the top (high Y value), and knocks several times.</p>
<p>Secondly, it occurs if the model (sliced with Cura) has a high Y value (eg: if the model occupies most of the bed).
(If there is room and I move the model - in Cura - closer to the front there is no knocking.)
On the first 10 (or so) layers the printer sometimes knocks when a high Y value is reached and the entire model is thereafter shifted to the front by a few millimeters.</p>
<p>There is a third scenario. At the end of a print the print head is in the middle of the bed and moves up 20 mm then travels directly to the top left corner. At this corner there are 4 or 5 &quot;knocks&quot; (and the nozzle is 20 mm above the bed).</p>
<p>Any suggestions to diagnose/fix this problem will be much appreciated.</p>

<creality-ender-3><print-quality><y-axis>
Why is my Ender 3 v2 knocking & misaligning for high Y?
Lewis Baxter
# Why is my Ender 3 v2 knocking & misaligning for high Y?

(Asked by: username_0 on 2022-08-12)

On my Ender 3 v2 printer I recently and consistently get some knocking.
This happens in only two scenarios.

First, it now occurs all the time when printing the initial test strip gets near the top (high Y value), and knocks several times.

Secondly, it occurs if the model (sliced with Cura) has a high Y value (eg: if the model occupies most of the bed).
(If there is room and I move the model - in Cura - closer to the front there is no knocking.)
On the first 10 (or so) layers the printer sometimes knocks when a high Y value is reached and the entire model is thereafter shifted to the front by a few millimeters.

There is a third scenario. At the end of a print the print head is in the middle of the bed and moves up 20 mm then travels directly to the top left corner. At this corner there are 4 or 5 "knocks" (and the nozzle is 20 mm above the bed).

Any suggestions to diagnose/fix this problem will be much appreciated.

**Tags:** creality-ender-3, print-quality, y-axis


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## 2 answers

### Answer by username_0 on 2022-08-19. Score: 4 | Accepted answer

Embarassingly, I discovered that the cable to the heatbed was sometimes caught between the on/off switch and the adjacent power plug. So, for high Y values the cable was very tight and the bed could not be moved. Presumably the "knocking" came from the Y-axis motor. The problem was fixed by attaching this cable to the adjacent hotend/X axis motor cable.

Hopefully this will be helpful to others who have a similar problem. Please add a comment if you experienced this.


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### Answer by username_1 on 2022-08-12. Score: 0

Your bed has become unleveled or skewed in Y direction.

When the nozzle is closer to the bed the extruder has to push harder to get the same filament flow through a smaller space, the stresses the extruder to a point that the stepper skips or grinds the filament. This is generally described as a knocking sound.

You need to find out why the bed is higher at the upper end of the Y range and fix this. Otherwise your bed has become warped and may need to be replaced. There are alternatives in using a sensor (e.g. a BLTouch) to sense the shape of the print surface, it will then automatically adjust for the shape during the first 10 mm (default value) of your print product. Installing a sensor requires new or alternative firmware.

> **Comments:**
> **username_0**: Thanks Oscar. That is very helpful if there were only 2 scenarios. But, I found a third that suggests that closeness of nozzle to bed is not relevant.  

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