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chrischin
(@chrischin)
Trusted Member
Stringy Infill

What might be causing this stringy infill? I read a post that recommended slowing infill speed down but I'm at 80 right now which is totally reasonable. First layer, perimeters, and top fill all look great. Filament is Prusament PLA and printer is an i3 MK3.  Print profile export attached.

When printing a 0.2mm 40x40 first-layer calibration square it looked perfect and measured exactly 0.2mm thick but the solid infill wasn't fusing well with the perimeter, it separated when pulling the square off of the build plate.  Also, the individual infill lines were separating and pulling up as separate strands.  Extrusion factor and extrusion multiplier calibration tests were both spot on.  This filament has been sitting in a bag for 8 months so I'm wondering if it's a material degradation issue, although there's no popping noises or steam coming from the extruded filament.  My PETG filaments of about the same age print like a dream but use different profiles than this PLA, and the PETG profile isn't drastically different other than temperatures.

This topic was modified 5 years ago by chrischin
Posted : 04/09/2019 3:41 pm
timo.m
(@timo-m)
Estimable Member
RE: Stringy Infill

Can you try to point out what exactly your problem is? Maybe with an Arrow in the picture? Your infill looks fine to me.

Posted : 05/09/2019 2:43 pm
chrischin
(@chrischin)
Trusted Member
Topic starter answered:
RE: Stringy Infill

These gaps circled in red.  Shouldn't the infill be a solid wall, just like the perimeters?

 

Posted : 05/09/2019 3:34 pm
Neophyl
(@neophyl)
Illustrious Member
RE: Stringy Infill

What infill are you using. That looks like rectilinear which looks like that as they are alternate directions in each. If you change to grid the layers will be stacked and touching, or cubic or gyro is etc. 

Posted : 05/09/2019 4:36 pm
chrischin
(@chrischin)
Trusted Member
Topic starter answered:
RE: Stringy Infill

Oh wow.  I had no idea rectilinear behaved this way.  At one point I wondered what the difference between grid and rectilinear was but never investigated it.  Thanks so much for helping troubleshoot this.  I'm printing mostly structural parts so this is a crucial setting to get right.

Posted : 05/09/2019 4:58 pm
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(@)
Illustrious Member
RE: Stringy Infill

Rectilinear infill requires adding material to fully fill the support pattern.  The default infill is set to 0.45 mm, I use 0.65 extrusion width to push out a bit more plastic and I generally get a good full layer with rectilinear.  With the 200 mm/s speed profiles, 0.65 is sometimes not quite enough, and as much as 0.85 is needed on large parts where the nozzle actually reaches full speed.  And I prefer it to grid infill for several reasons.  

 

Posted : 05/09/2019 5:31 pm
chrischin
(@chrischin)
Trusted Member
Topic starter answered:
RE: Stringy Infill

Why do you prefer it over grid? Seems like they're the same thing other than rectilinear laying down intermittent layers.

Posted : 05/09/2019 5:38 pm
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(@)
Illustrious Member
RE: Stringy Infill

Rectilinear is much faster, and doesn't incur the thump-thump of the extruder bumping over a spot it has already laid down filament.  I've worn out nozzles with grid infill. This was an E3D-V6 Nickel on Copper ... lol.

Posted : 05/09/2019 6:23 pm
chrischin
(@chrischin)
Trusted Member
Topic starter answered:
RE: Stringy Infill

The first rectilinear infill layer will have an extra wide line if infill width is set to 0.65.  Have you seen this cause issues with any prints?

Posted : 05/09/2019 7:12 pm
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(@)
Illustrious Member
RE: Stringy Infill
Posted by: christian.p17

The first rectilinear infill layer will have an extra wide line if infill width is set to 0.65.  Have you seen this cause issues with any prints?

Never

Just finished this an hour ago:

This post was modified 5 years ago by --
Posted : 05/09/2019 9:11 pm
ron
 ron
(@ron)
Estimable Member
RE: Stringy Infill
Posted by: christian.p17

Why do you prefer it over grid? Seems like they're the same thing other than rectilinear laying down intermittent layers.

I prefer rectilinear mainly to avoid build up of material on the nozzle due to crossing pathes. I use a lot some filaments that build up very easily on the nozzle. there are other non crossing infills that i may use but rarely.

Posted : 11/09/2019 9:04 am
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