exxos's Atari, Amiga & retro forum

It is annoying and I cannot seem to figure it out :(

I marked on red where the blobs are happening.


The head slows down the changing direction so you would think extrusion is still happening causing it to blob up. The problem is I cannot actually find a cause :(

If I reduce the head temperature makes no odds. If I fiddle with the linear advance all it does is start creating gaps before the blobs. Changing printer speed or acceleration has no effect either. I even tried 1mm coasting at the end of the lines. Made no odds.

So there does not seem to be any setting to prevent this ?!

I wonder if the X-axis is causing it as my first block is supposed to be 57mm wide and its 56.68mm :roll:

EDIT:
Nope, 100mm moves exactly 100mm . I don't get it.

What slicer are you using - can you look for a retract setting that you can increase slightly? Perhaps even reduce overall feed rate.

Aeberbach wrote: 13 Oct 2023 00:10 What slicer are you using - can you look for a retract setting that you can increase slightly? Perhaps even reduce overall feed rate.

It's simplyfy 3D. Retract and 90% feed rate don't help.

It may be print speed. I think the straight lines appear under extruded because it's to fast. Then there is a delay in melting and when it slows down on the corners the pressure catches up and ends up in a lump on the corners.

It looks like all of your direction changes happen in the corners, so you're probably getting a build up where the change happens and you have a 'curl' of plastic in 2 directions.

Can you change the way the printing happens to avoid the directional changes happening in the same place?

rubber_jonnie wrote: 13 Oct 2023 08:51 Can you change the way the printing happens to avoid the directional changes happening in the same place?

I don't see how that's possible. It's basically a square so it's always going to have corners and changes in those places. The only possibility is to use rounded corners. But I'm going to try lower speeds next.

How dry is your filament?

stephen_usher wrote: 13 Oct 2023 10:23 How dry is your filament?

Brand new as of last night. Was sealed etc.

I have upped the coasting at end of line to 1mm. I did not realise the corner stop and start points were changing every few layers. The widely the bottom right corner (shown with the biggest gap) is the first couple of layers only and that seems to blob up right away despite the coasting. So I am just going to let it run for a while and see the evenings out.

Looking at your picture again, where it turns the corner, it's got to slow down to change direction.

At that point, the head has to slow down and the rate of flow continues at the same rate, leading to more plastic being laid down.

Can you slow the flow rate during direction changes? Or change the speed when it changes direction?

I'm a bit rusty with 3d printing, I need to get back to it...