Single strains on a print

[bjoernw]

Hello,

I just printed a phone stand I designed and did get the error:

“Abnormal accelerometer data detected.”

The printer was still printing and I let it finish my print.
After turning the machine off and back on the error message was gone but my print looks a bit funny.

There are single pla strains on the underside that can move.
Is that because of the error or maybe a mistake in my design?

Thanks for helping out. Im pretty new in this hobby.

[johnfcooley]

re-run calibration.

[Slarm]

Looks like an unsupported overhang, or if it was supported, the Z gap was too large for the support to be effective. On top of that there may be another issue but definitely appears to be a problem with the settings chosen during slicing.

[lkraus]

Your bottom picture shows holes and lines in the top surfaces indicating under extrusion - your flow rate is too low for this filament and the filament is not “squishing” enough to the sides to fill the gap to the adjoining line. Calibrate the flow rate. The manual coarse and fine procedures explained in the Wiki will work. When evaluating the samples, pick the sample with the smoothest central area.

This is not the graphic I was looking for, but the top two parts might help explain what is happening with the long bridges on the underside (besides under extrusion).

Normally, your flow rate is set to produce a line of a specific width after it is pressed into the bed or previous layer. The nozzle path is spaced so that the sides of the extruded filament are also forced against the line next to it. With no support and nothing to press against, the filament takes a narrower, more circular shape and adjoining lines never touch or adhere to each other. The extrusion also tends to stretch and sag over long unsupported distances, it also cools a bit quicker and so is less sticky. Because that layer is poor, the layer above it is also affected to some degree, and the layer above, etc. The longer the bridge, the worse the problem. Adding support turns a long gap into multiple short ones that can produce a acceptable surface.

[bjoernw]

Thanks for your fast help.

To be honest I think that @Slarm is right with his answer.

I wanted to use less filament and printed it without supports. So the whole middle surface wasn’t supported.

Maybe that was the wrong decision or need to be done differently.

[jhermann]

The question is why do you have that recess in the bottom where nobody can see it anyway. What I do on the bottom of stands is build in shallow spots for rubber nubs which will stabilize the stand later on. These are small and shallow and thus easily bridged without support.

[bjoernw]

I tried to keep the bottom hollow to safe material like in the second picture. That’s why I did it.
Now its like closed and should work but it needs more material.

[MZip]

You probably already are aware but just in case, you can also cut back on infill density and number of walls if that extra filament used without the hollow area is too much.

[jhermann]

Progressive infill will cut down on material use further, and only be dense at the top where it needs to support surfaces. Not for heavy loads, but “just to fill the space” it is enough.

Most material is spent in the bottom surfaces anyway, cut down on those but accept the peril of a weak object.