Issues with bridging with PC and PETG

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anlambe2
Posts: 9
Joined: Tue Sep 07, 2021 7:49 pm

Issues with bridging with PC and PETG

Postby anlambe2 » Tue Sep 07, 2021 8:06 pm

Hi All,

I have been trying to perform some calibration tests on a Pro2 Plus. Using a PEI sheet with PC, my temperature tests are absolutely garbage. The bridge never completes correctly. I have the same issue with the temp test bridge a BuildTak sheet with my PETG. Picture attached of a PC run (black filament) With some temp ranges as well as a PETG run (blue filament) with some information. I print both of these on the 0.4mm nozzle on my right extruder. Left extruder completely off. I am wondering if I need to bump the flow rate up. I tried messing with bridge speeds but I did not see much if any improvement. Please advise on where I can start to dial this in.
Attachments
20210902_175746.jpg
20210901_155253.jpg

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Steven@Raise3D
Posts: 477
Joined: Thu Dec 17, 2020 11:24 pm

Re: Issues with bridging with PC and PETG

Postby Steven@Raise3D » Thu Sep 09, 2021 12:41 am

anlambe2 wrote:Hi All,

I have been trying to perform some calibration tests on a Pro2 Plus. Using a PEI sheet with PC, my temperature tests are absolutely garbage. The bridge never completes correctly. I have the same issue with the temp test bridge a BuildTak sheet with my PETG. Picture attached of a PC run (black filament) With some temp ranges as well as a PETG run (blue filament) with some information. I print both of these on the 0.4mm nozzle on my right extruder. Left extruder completely off. I am wondering if I need to bump the flow rate up. I tried messing with bridge speeds but I did not see much if any improvement. Please advise on where I can start to dial this in.


The settings will vary from material to material. This video goes into pretty good detail on how to adjust the bridging settings: https://www.youtube.com/watch?v=4KAMFamy3zw

svandru
Posts: 58
Joined: Tue Dec 31, 2019 5:48 pm

Re: Issues with bridging with PC and PETG

Postby svandru » Sat Sep 11, 2021 2:02 am

Bridging speed won't affect the outcome. I do not understand what ideaMaker considers a bridge, but you will probably find that nothing in that model is considered a bridge if you check it in the structure preview...

PETG and PC (especially) are hygroscopic. Even brand new vacuum sealed spools can be too damp. I dry every spool I buy except for PLA. If you are using the same nozzle with the different filaments, you could also have a nozzle clog. The bottom of that PC tower looks like you are definitely not laying down enough filament, more so than the few percent you might adjust flow rate.

I am mostly familiar with PETG, so I will just talk about that. Your prints look pretty bad all over, not just the bridges. There are odd strings on the sidewall and at the corners of the overhang; it doesn't look very glossy, either. You did not say what brand filament you are using, but the Raise3D PETG template sets the nozzle to 255° and the fan at 100%. Maybe you are starting too cold if you are using their filament. I don't have a Raise3D printer myself. I use PolyMaker PolyLite at 230° with 50% fan and my generic templates use 240°/50%.

Whenever I test a new filament, I start at the halfway point in the manufacturer's recommended temp range and a speed of 45mm/sec (less for flexibles) everywhere but the first layer where I use 30mm/sec. I start with basic recommendations for cooling (PLA 100%, PETG 50%, ABS/PC/Nylon 0%, etc.). My first print is a 20mm square, 10mm tall open-top box with a 2 perimeter/1mm thick wall (no infill) to test for a good first layer, gloss, stringiness, accurate dimensions and flow rate. The box only takes 7 minutes, so I could print quite a few in the 2 hours it takes to print one temperature tower. When I am satisfied with the box, I move to a very small vase-mode model to check for cooling. Then I print a swatch card for future reference. Finally a Benchy to verify everything. I no longer bother printing temperature towers unless I have a specific problem to work out such as overhang or bridging.

Good luck and I hope this is helpful.

anlambe2
Posts: 9
Joined: Tue Sep 07, 2021 7:49 pm

Re: Issues with bridging with PC and PETG

Postby anlambe2 » Tue Sep 14, 2021 12:35 am

svandru wrote:Bridging speed won't affect the outcome. I do not understand what ideaMaker considers a bridge, but you will probably find that nothing in that model is considered a bridge if you check it in the structure preview...

PETG and PC (especially) are hygroscopic. Even brand new vacuum sealed spools can be too damp. I dry every spool I buy except for PLA. If you are using the same nozzle with the different filaments, you could also have a nozzle clog. The bottom of that PC tower looks like you are definitely not laying down enough filament, more so than the few percent you might adjust flow rate.

I am mostly familiar with PETG, so I will just talk about that. Your prints look pretty bad all over, not just the bridges. There are odd strings on the sidewall and at the corners of the overhang; it doesn't look very glossy, either. You did not say what brand filament you are using, but the Raise3D PETG template sets the nozzle to 255° and the fan at 100%. Maybe you are starting too cold if you are using their filament. I don't have a Raise3D printer myself. I use PolyMaker PolyLite at 230° with 50% fan and my generic templates use 240°/50%.

Whenever I test a new filament, I start at the halfway point in the manufacturer's recommended temp range and a speed of 45mm/sec (less for flexibles) everywhere but the first layer where I use 30mm/sec. I start with basic recommendations for cooling (PLA 100%, PETG 50%, ABS/PC/Nylon 0%, etc.). My first print is a 20mm square, 10mm tall open-top box with a 2 perimeter/1mm thick wall (no infill) to test for a good first layer, gloss, stringiness, accurate dimensions and flow rate. The box only takes 7 minutes, so I could print quite a few in the 2 hours it takes to print one temperature tower. When I am satisfied with the box, I move to a very small vase-mode model to check for cooling. Then I print a swatch card for future reference. Finally a Benchy to verify everything. I no longer bother printing temperature towers unless I have a specific problem to work out such as overhang or bridging.

Good luck and I hope this is helpful.



Thanks! This is some incredibly helpful information. The Raise3D PETG Filament I bought says 230-240C on the box. I find it interesting that at 245C my temp tower had the best quality. I will definitely be running some more trouble shooting with higher temperatures and adjusting other things. The first layer of the bridging space of this temp test is considered a bridge on the slicer, which is why I thought it is mainly a bridging problem.

Can you share your small box you use to test?

svandru
Posts: 58
Joined: Tue Dec 31, 2019 5:48 pm

Re: Issues with bridging with PC and PETG

Postby svandru » Tue Sep 21, 2021 3:00 pm

Can you share your small box you use to test?

I'm happy to share my little box. Here it is:
Attachments
Flow Rate Hemi-Cube.stl
(684 Bytes) Downloaded 4 times


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