Run Out of "Knobs" to Turn

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Gwhite
Posts: 372
Joined: Tue Jul 11, 2017 3:38 pm

Re: Run Out of "Knobs" to Turn

Post by Gwhite » Thu Oct 25, 2018 6:05 pm

ednisley wrote:
Thu Oct 25, 2018 3:36 pm
Gwhite wrote:
Thu Oct 25, 2018 3:05 pm
layer change is combined with going back & forth
Preview the infill pattern through that section: I suspect a difference directly inside those "defects" which changes the structure just enough to affect the perimeter threads. If so, perhaps picking a different infill pattern might shake the dice enough to produce a less-annoying outcome.

You can see surface changes you can't measure.
Interesting idea. I'm printing 100% infil, which may be part of the problem. I've heard some people claim they get better results on some models at ~ 80%. I will try that & see what happens, although I would think having 3 perimeter layers would isolate the outside from any infil variations.

Gwhite
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Joined: Tue Jul 11, 2017 3:38 pm

Re: Run Out of "Knobs" to Turn

Post by Gwhite » Thu Oct 25, 2018 6:29 pm

airscapes wrote:
Thu Oct 25, 2018 5:04 pm
Have you tried to print 2 or more at once? That almost looks like too much heat as the nozzle is always close .. found this to be an issue when printing some really small miniatures .. Can you post the SLT? I have the .5 nozzle on the M2 atm and won't change it for a few days (have to print some Ninjaflex this weekend.. but after that I can put the .25 on and see what it looks like.
Here's the SLT:
Pardini SP ECI Test.stl
(374.98 KiB) Downloaded 315 times
The part is pretty small, only about 1" high.

Hmmm. I do have an option set to slow down to as little as 20% for printing layers below 10 seconds. I wonder if the combination of support and the larger diameter near the top of the cone is pushing it over that threshold. The size of the defect seems to grow roughly linearly as you get near the top of the cone, so I suspect that's not the issue. Besides, slowing way down is supposed to help...

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ednisley
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Re: Run Out of "Knobs" to Turn

Post by ednisley » Thu Oct 25, 2018 7:54 pm

Gwhite wrote:
Thu Oct 25, 2018 6:05 pm
better results on some models at ~ 80%.
Absolutely! Building a solid block of plastic from threads requires perfect settings, which straight-up can't happen over the entire part: the physics changes as the cross-section changes. Even a "solid" part has internal voids, so it's not going to be waterproof.

I've been running PETG around 15% infill for "ordinary" stuff and 50% for "strong" parts, based mostly on an old study comparing strength vs infill (vs lots of other parameters) for an entirely different plastic:

http://my3dmatter.com/influence-infill- ... t-pattern/

Cutting the infill back to 70% might let you optimize the other parameters or spend way too much time playing (pronounced "experimenting") with your settings. [grin]

airscapes
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Re: Run Out of "Knobs" to Turn

Post by airscapes » Thu Oct 25, 2018 11:12 pm

unless this is going to hold a TV to the wall I would have 2 shells, 3 top/bottom layers and infill of 15-25 percent

Gwhite
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Re: Run Out of "Knobs" to Turn

Post by Gwhite » Mon Oct 29, 2018 2:43 am

The parts will get whacked a bit in use, which is why I want them to be sturdy. I'm hoping the PLA+ won't be as brittle as straight PLA, but I may eventually have to try another material.

In any event, I applied several of the suggestions. I dropped the infil down to 80% from 100%, and it changed the points where the extruder went back & forth to the support material, so the "seams" didn't overlap. I then modified the starting points to be at the nearest corner, and that helped even more. I now have one seam, and although it isn't perfect, it's at least a single line and close enough to the corner that it doesn't stand out as much.

Here's a photo showing the progression from the original mess to the final version:
Pardini ECI Debug.jpg
Thanks to everyone for their inputs!

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