3
$\begingroup$

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.

Improve this question
$\endgroup$

2 Answers 2

Reset to default
4
$\begingroup$

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.

Improve this answer
$\endgroup$
0
0
$\begingroup$

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.

Improve this answer
$\endgroup$
1
  • $\begingroup$ 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. $\endgroup$
    – Lewis Baxter
    Aug 13, 2022 at 13:27

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .