What's going on here and how can I fix it?
I'm in the process of creating the LACK enclosure. While printing out the parts, this happened:
These strands were a little loose and they did not bind with the layers above them. There is actually a crackling sound when I run my finger across them. Is this a bridging problem? If so, how can I fix it?
I thought these things were supposed to print without modification. Why did they not put in supports?
Any help would be greatly appreciated.
Thanks
RE: What's going on here and how can I fix it?
That's normal bridging.
RE: What's going on here and how can I fix it?
Are those first few layers supposed to be loose? Seems like poor design
RE: What's going on here and how can I fix it?
That's how bridging works. There are settings you can tune to improve it, but at the end of the day you're still printing in air, and hot plastic sags a bit and has nothing to "squish together" on underneath it.
You can re-slice it yourself and add supports instead... but for parts like this where the dimensions are not critical and it has no structural strength requirement in that area, it's common to sacrifice a bit of appearance for the reduced print time and post-processing.
RE: What's going on here and how can I fix it?
So is it normal to just leave it alone? Do people usually scrape and/or sand off a couple layers?
RE: What's going on here and how can I fix it?
So is it normal to just leave it alone? Do people usually scrape and/or sand off a couple layers?
You can try to position the part so it's not visible, design the part so bridging is not required, or print in parts for later assembly to no bridging is required. It's a fundamental limitation of current consumer-grade FFF 3D printing.
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RE: What's going on here and how can I fix it?
If your using PETG, try ticking detect bridging parameters, and set bridge flow rate to 0.8 and bridging cooling to 100
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: What's going on here and how can I fix it?
If your using PETG, try ticking detect bridging parameters, and set bridge flow rate to 0.8 and bridging cooling to 100
I’ll try this. You say, “If you’re using PETG...” does this option only work for PETG? Sometimes I’ll do things in PLA.
RE: What's going on here and how can I fix it?
It's just that PETG tends to be stringy anyway, and reducing the setting to 0.8 will cause it to stretch a bit, where PLA may not be able to stretch as much. If the strands break, then try 0.85.
I'm not at home at the moment, but I have some quick bridging, stringing test models I use for getting settings dialed in quick before I go for a full print, I can post them tomorrow or just cut something like this down to one section including a bridge to test settings.
https://www.prusaprinters.org/prints/4667-all-in-one-temperature-bridging-tower-pla-petg-gco
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: What's going on here and how can I fix it?
It's just that PETG tends to be stringy anyway, and reducing the setting to 0.8 will cause it to stretch a bit, where PLA may not be able to stretch as much. If the strands break, then try 0.85.
I'm not at home at the moment, but I have some quick bridging, stringing test models I use for getting settings dialed in quick before I go for a full print, I can post them tomorrow or just cut something like this down to one section including a bridge to test settings.
https://www.prusaprinters.org/prints/4667-all-in-one-temperature-bridging-tower-pla-petg-gco
I’ve seen something like this before. So that then brings me to another question. Along with this bridging test and other calibration tests, how often should I be printing these test models? Before every big print? Weekly? Monthly? What do people with big farms do?
RE: What's going on here and how can I fix it?
When you use a new filament from a different brand or a different color just to get the best settings for that material.
Once you have the settings for that particular brand and color, you don't need to run tests again unless the supplier changes the formulation.
And yes, color affects printing properties even if the filament is the same type and brand as they will have different additives. The more opaque and bright a filament color, the more titanium dioxide needed whereas a transparent filament will have none. Basically each manufacturer will have their own blend for their filaments, for example, I'm currently using SUNLU black PETG which prints at PLA temperatures 215 Deg C, whereas Technology Outlet PETG has to be printed at 245 Deg C, yet they are both supposedly PETG.
Pure PET melts at 260 Deg, PETG typically prints at 230 Deg, so you can see, both filaments are not just PETG, but some sort of PETG with manufacturer additives in the blend, possibly some TPU, possibly some PLA, who knows?, (Which can be a bit worrying)
So really you only need to test each filament once and if you use the same filament later, there should be no need to re-test.
Note: Cheaper brands may recycle rejects by cutting up the reject filament and mixing it back into the new filament, this can alter the levels of additives in the blend between batches and cause some inconsistencies, so you may find you need to adjust settings between reels with the cheaper filaments.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.
RE: What's going on here and how can I fix it?
When you use a new filament from a different brand or a different color just to get the best settings for that material.
Once you have the settings for that particular brand and color, you don't need to run tests again unless the supplier changes the formulation.
And yes, color affects printing properties even if the filament is the same type and brand as they will have different additives. The more opaque and bright a filament color, the more titanium dioxide needed whereas a transparent filament will have none. Basically each manufacturer will have their own blend for their filaments, for example, I'm currently using SUNLU black PETG which prints at PLA temperatures 215 Deg C, whereas Technology Outlet PETG has to be printed at 245 Deg C, yet they are both supposedly PETG.
Pure PET melts at 260 Deg, PETG typically prints at 230 Deg, so you can see, both filaments are not just PETG, but some sort of PETG with manufacturer additives in the blend, possibly some TPU, possibly some PLA, who knows?, (Which can be a bit worrying)
So really you only need to test each filament once and if you use the same filament later, there should be no need to re-test.
Note: Cheaper brands may recycle rejects by cutting up the reject filament and mixing it back into the new filament, this can alter the levels of additives in the blend between batches and cause some inconsistencies, so you may find you need to adjust settings between reels with the cheaper filaments.
What about when using MMU? If they use different settings is there a way to choose settings on a per-filament level? Or is it per print?
RE: What's going on here and how can I fix it?
Sorry can't help with MMU, don't have one.
Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet.