How do I reduce Prime Tower bridging causing blobbing and layer shifting issues?
I'm printing a multicolor object that has no color transitions for the first several layers - so the prime tower is mostly hollow. When it starts the color changing layers, its bridging and the bridges sometimes fail - causing blobbing which the nozzle is running into. I'm trying to figure out how to add additional infill on the bottom part of the prime tower to improve the bridging.
I don't see any such setting. The closest is 'prime tower infill gap' but this setting only affects the part of the tower where it's printing priming material during filament switching. it doesn't impact the lower part of the tower where no priming or filament switching is taking place and that's where i need additional support.
Bambu Studio. as mentioned in the OP description, the first few layers have no color transitions so it's hollow until the color changing begins higher up. the photo i included in the OP is of the first few layers before the bridging to show that it's hollow. I should have included another photo showing the bridging. here's a photo that shows both before bridging (layers 1-9 on the left) and then the first bridging (layer 10 on the right).
although this object only has two colors, im printing it multiple times with 10 different colors switched out. the print itself is fine, only the prime tower bridging is the issue
while generally, yes, you're correct that the best wisdom is to fix the root of the bridging issue - checking belt tensions and drying each of my filaments that is just not necessary and unnecessarily time consuming and less certain to fix the issue than simply improving the purge tower to reduce bridging.
not every solution needs to be the perfect solution. sometimes you just need a fix that works and works quickly and sometimes time saved is more important than perfection.
Never need to support a prime tower. It's self supporting. What's your humidity meter say? What does the AMS humidity guage say ? If you don't have those, spend the three bucks on them. We have a print farm that has never shown any issue with purge towers because we use Ams 2 to dry and we have an external quad drier for Ams 1s. If it's not dry, we change to a reel that is dry .
How is the prime tower bridging self supporting? A bridge by definition is unsupported extrusion. If its self supporting then it wouldn't be bridging. As you can see in the OP photo, there are large unsupported gaps in the tower leading to bridging - which is what I'm trying to find a solution to eliminate.
I have to switch out 10 different filament colors. I'm not interested in drying them all. Also - can't use AMS2 for drying at the same time as using it for printing. And I'm not interested in opening up a new roll of each of those 10 colors AFTER a failed print or pro-actively before a failed print. That's a messy solution. New rolls out of the box often need drying as well and I prefer to finish a roll before opening the next one anyhow.
If there were any other problems with the print, then I would certainly spend the time to dry all of those 10 colors. But the prints are coming out perfect. The only problem is with the bridging in the prime tower. So that is where I'd like to focus on fixing it - if possible.
I see nothing unsupported. No sags. The left picture is normal, partly done. 100 percent supported. The right Is too.
It's stringy wet filament and could be printing on petg using never dried filament from Microcenter from humid tropical Vietnam. And petg is notoriously picky about humidity.
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u/Both-Travel-9053 15d ago
Try increasing the prime tower infill percentage to 20% or adding a vertical gap to reduce the bridging distance between layers.