I was printing an iPhone case and noticed where it seems like most of

3D Printing
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1

I was printing an iPhone case and noticed where it seems like most of one pass appears to be missing. 1st layer speed is much slower and at 150% height, etc. But is this an example of skipping steps? I’ve seen these drop-outs before when it’s making long passes. What does the output for skipped steps look like?

I’m running Marlin/RAMPS via OctoPi.

365812a214fb08e1df40e158607f35c3.jpeg
365812a214fb08e1df40e158607f35c3.jpeg3024×4032 1.9 MB

2

I don’t know for sure but looks more like shrinkage.

3

"You are holding it wrong"© :wink:
Seriously, I believe that’s just the plastic shrinking. Turn off the parts fan but keep the bed on for first several layers.

Skipped steps will look like severely distorted geometry of the part.

4

I should’ve clarified, printing in PLA and fan doesn’t come on until after 1st layer…and it’s set to 60% speed.

5

Looks like slightly off in the squish to me too. In fact, looks like a bit of a ripple in the “squish” there. Ultimately resulting in an incorrect line width.

David’s suggestion seems reasonable to me. You might also consider increasing extrusion a bit on the first layer. But again, David’s suggestion is basically doing this by increasing temp, going slower, and decreasing z. Which will slightly increase line size from the squish and allow more time for them to bond before cooling.

IMO, if you simply up the temp and extrusion a hair on the first layer you’ll get the same result.

6

Looks like the extruder may have skipped… any noise associated w the error?

7

Could also be backlash causing some lost motion / under-travel, or it could be the bed shifting.

8

It looks like it was printed in two different steps, going in opposite directions, not one continuous.

9

My money is on backlash or mechanical slippage somewhere.

10

Looks like backlash. Try printing some cylinders. You’ll see it will be weirdly flat on the sides.
It’s typically caused by poor belt clamps or a very loose belt.

Also make sure the hotend is primed, make sure the skirt has enough loops or set the minimum extrusion length.

11

@David_Sherwood I agree with you on this. Same happened to me a while ago. Plus, adjusting the extrusion also helped to get rid of those missing lines.