Horrible infill on higher speeds

[kazzaqov 0]

Hello guys,

At 100mm/s the infill is horrible and ruins the print. Is there any way to fix this? Temperature is 220 degrees, PLA. I had hoped Ultimaker can print fine at 100mm/s

 

[gr5 897]

1) The infill looks okay to me in the picture but if you say something is wrong then I believe you. What is the problem exactly? Would solid infill fix the problem?

2) I can print fine at 100mm/sec but only if layer height is .1mm. If it is .2mm then I need a temp > 240C. 100mm/sec with .2mm layer at 220 is just too much pressure in the nozzle. The extruder slips and I don't get enough plastic.

3) In another photo, the very first layer is thin in some spots, thicker in other spots. This looks okay to me but if you need it flatter you need better hardware (straight rods, flat bad).

4) You don't have the standard fan shroud. Your fan is blowing on the nozzle. This means your nozzle tip is colder than normal. This means you need to print hotter than normal. I'm not sure how much hotter. Maybe 250C? I recommend you print this:

http://www.thingiverse.com/thing:17602

 

[illuminarti 16]

What slicer are you using? This looks like simple straight-line infill of older versions of Cura? For high speed printing, you might do better with a more structured infill, such as hexagonal/octagonal infill that lays down the same pattern on every layer. Or try the latest Cura, which has a more regular square pattern - which can have its own problems at very high speeds (like 300mm/s) but should be fine at 100mm/s, provided your layers aren't too thick - what layer height are you printing at?

 

[alex-marakesch 0]

More temp should be fine. And one more thing, do you print exactly size, or you use some error correction percent ?

 

[nick-foley 4]

I get the same thing with the latest versions of Cura. I don't think the newer versions are adequately compensating for desired extrusion vs actual extrusion rates when changing speed and density. Low % support structures and infill settings (sub 40) almost always turn into a fluffy mess for me unless I'm printing at 60mm/s or lower.

 

[gr5 897]

Low % support structures and infill settings (sub 40) almost always turn into a fluffy mess

 

Sounds like underextrusion due to printing too fast.

 

[illuminarti 16]

The less-than-100%-dense support has always seemed like a bit of an unpredictable mess to me, and it does affect nozzle pressure, and so tend to bleed over into regular 'solid' parts of the print nearby.

The infill is different issue though - it's printed with 100% extrusion rate... so it shouldn't affect head pressure. Past versions of Cura had issues where the infill didn't print totally solid on each layer - it did passes in one direction on one layer, and one on the other. That did tend to cause problems with layer adhesion and proper extrusion, since every layer's infill was effectively bridging over a layer of empty space, except at the crossover points. In the latest version, cura prints a full square grid on each layer which works much better as a rule. I've only seen two issues with it:

1) When printing very fast (e.g., 250mm/s - maybe a bit slower) the head jumps slightly as it hits and crosses over the previously extruded infill passes on the same layer, causing the filament thread to break and vibrations in the bed, and it just makes a mess.

2) The infill position is tied to the extents of each layer, not fixed relative to the bed. As a result, infill may not exactly line up from one layer to the next, and so some of the same problem of printing infill-over-space can recur. This should be easy to fix (relatively speaking) by anchoring the infill relative to the center of the bed, rather than allowing it to wander.

 

I get the same thing with the latest versions of Cura. I don't think the newer versions are adequately compensating for desired extrusion vs actual extrusion rates when changing speed and density. Low % support structures and infill settings (sub 40) almost always turn into a fluffy mess for me unless I'm printing at 60mm/s or lower.

 

[gr5 897]

I'll try new fan holder. Btw, what printing speed would you recommend for 0.2 layer thickness?

 

I like 50mm/sec if temperature is < 225C and 100mm/sec if temp is >=230C

 

I get lots of blobs on solid outlines.

 

OH! I didn't notice that. This is a common problem with the new Cura. The infill sometimes destroys the skin/shell. If possible I recommend .8 or 1.2mm for "shell thickness" in Cura but maybe that won't work with your phone case.

Alternatively you can reduce the infill overlap to a negative value. Try -25% maybe?

Even better, try the older cura, (13.04) when you have blobs on the outside edges.

Here is a brief description of the problem:

http://umforum.ultimaker.com/index.php?/topic/2501-is-this-slicing-settings-or-hardware-problem/?p=17683

 

[illuminarti 16]

He is already using 'old Cura', so it's not infill showing through.

 

OH! I didn't notice that. This is a common problem with the new Cura. The infill sometimes destroys the skin/shell. If possible I recommend .8 or 1.2mm for "shell thickness" in Cura but maybe that won't work with your phone case.

Alternatively you can reduce the infill overlap to a negative value. Try -25% maybe?

Even better, try the older cura, (13.04) when you have blobs on the outside edges.

Here is a brief description of the problem:

http://umforum.ultimaker.com/index.php?/topic/2501-is-this-slicing-settings-or-hardware-problem/?p=17683

 

[olivierc 2]

The less-than-100%-dense support has always seemed like a bit of an unpredictable mess to me, and it does affect nozzle pressure, and so tend to bleed over into regular 'solid' parts of the print nearby.

 

Interesting, so do you recommend using a 100% density for support? because I have this problem with the new cura where the supports are generated a bit too close to model and end up touching it. and I hardly notice any difference when I lower with the density anyway, supports are still hard to remove

[illuminarti 16]

To be honest, I mostly recommend just avoiding support at all costs. :-) You can print a heck of a lot without it, especially if you have the luxury of re-orienting the model, or splitting it up.

But if its unavoidable, higher densities may help, yes. Also, I see Daid just posted about 'New! Improved!' support that will be in Cura soon. Hopefully that will work better.

 

[olivierc 2]

Yup, just saw the new support thread. I indeed try to avoid support when possible, but sometimes you don't really have choice.