Underextrusion and seam with spiralize

[Nicolinux 288]

Hi,

I have two problems with the following print:

Although it was printed at normal speed, the extruder started skipping and underextrusion occured. Initially I lowered the temperature in order to prevent the forming of blobs (which from my understanding would form from either too much pressure or high viscosity at high temperatures).

Key print settings are:

 

• layer height: 0.2
  
• shell: 0.8
  
• bottom/top: 1.2
  
• speed: 50
  
• temperature: 230 (later on 225)
  
• spiralize: on
  

The model is still full of small blobs. And while I am asking for 4mm^3/s filament, it still started underextruding at 225°. I don't want to raise the underextrusion red flag and blame the extruder - just wondering why this would happen under those circumstances.

The second issue (albeit not that important) is the visible seam on the model. I thought spiralize would get rid of it. What might be the reason for the seam then?

 

[gr5 1,968]

Actually it is trying to do 8mm^3. I'm impressed it did so well.

The problem is with spiralize: it does it in a single pass so it is trying to do 200% flow to get that shell of 0.8. It's tough to squeeze .8mm wall out of a .4mm nozzle so it just can't quite do it. I think if you do .5 or .6mm shell you will be good.

 

[Nicolinux 288]

No wait, according to the help tooltip for spiralize it does a single wall so it ignores the shell setting. And the print really does look like it is a single wall - it is very thin.

 

[Nicolinux 288]

Ok, I understand now what you say. Then I could simply either reduce flow to 50% or re-slice and chose a 4mm shell.

thx.

 

[gr5 1,968]

But it does 2X extrusion. In cura look at meters of filament used. Then change shell to .4 and you will see it will reduce by quite a bit (the part for the wall - the base will use the same amount).

 

[gr5 1,968]

hen I could simply either reduce flow to 50% o

 

Yes, but not until it gets to the wall.

 

[gr5 1,968]

I recommend at least .5mm shell by the way. If you want this to be watertight.