P1S with AMS will NOT bridge PETG acceptably

Since day one, my P1S can not bridge more than 3mm acceptably with PETG, due to sagging. Before you respond, I have tried to reduce the bridge flow rate. Check and uncheck thick bridges. Slow down the speed to a veritable crawl. Speed up the speed, to full. I’ve been troubleshooting this issue for a while. Is this issue only my machine, or are others having this problem as well? Any ideas or anyone faced the same issue and conquered it? Im on the verge of a support ticket.

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Including pictures and detailed information about the print speeds, filament type and settings used will help get the appropriate solutions.

I have printed some PETG temperature towers that have had some decent bridging at certain temperatures.
But I am not sure what you consider “acceptable”.

I don’t have many pictures on hand but would you consider the 265-270 an acceptable bridge?

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The base profile isn’t set up for long bridging. Its set up for speed. There are some tradeoffs you’ll need to make for bridging.

  • Generally cooler temps make for better bridging, but as shown above, that’s not universal. However, cooler temps are almost always worse for speed and strength.
  • Some filaments bridge better than others, even in the same family. Not sure I’ve ever tried to bridge Bambu’s PETG, but it doesn’t strike me as one of the better blends for that. Its very tough, but that means its likely a little more pliable when hot (bad for bridging).
  • If your filament choice doesn’t warp easily, try more fan. But note, Bambu’s profile has pretty high fan settings for PETG.
  • Make sure your not over-extruding.
  • Equally, turn down extrusion for bridging. This is found in the “Quality” tab in the slicer, under Bridging. There are two ratios. Try 0.80 - 0.95, depending how bad your filament droops.
  • Slower speeds can help in bridging too. In the “Speed” tab, there is a Bridge speed setting. One for the overall bridging speed and one for the internal bridging speed. 50mm/sec is the default and the second is a percentage of that (150%). Both seem high for bridging. The first only a little high, but the second seems very high. Play with the settings and see what works for you and your filament.

The two most important, IMO, are Bridging speeds and Bridging flow rate (after you’ve found a good overall temperature). Set up a simple fast test bridge and play with those two settings (three if you count the temps) and you will be bridging fine. In slicer, you can use modifiers to test 2 or 3 different settings at once (but not different temps, unless you are doing a tower). I built out 3 quick bridges in slicer, all with different settings and found the settings that worked best for me. Sure you can do the same. Just keep the models low so they print fast and waste very little filament and time. Here’s an example:


Again, I haven’t played around with bridging PETG to crazy lengths, but this should work.


First off, thanks for taking the time. I’ve went through every potential cause of failure you mentioned. After that went nowhere I started messing around with infill wall overlap and if i crank that to 100% i can bridge pretty decent with thick bridges checked. Its just like WHY would everyone else be ok at 15% infill overlap but my machine fail every single time. Ive tried dozens of times to bridge something

Thanks for the tip. The infill overlap makes sense and was a noticeable improvement.

I ran a calibration last night before bed. Going to test it to see if it helps now. Also considering a hard reset of the printer. Reset to factory defaults and a reinstall of orca slicer

Your test piece looks like a problem. That is not normal.

I did a 65mm bridge with some Polymaker PETG and it wasn’t great, but wasn’t that bad. And that was without any profile tweaks. In all honesty, it was better than the BBL PLA bridges I’ve tested. I think resetting somethings is a good idea.

the bridge is horrible my friend. that is not acceptable. What helped a lot was to turn on the aux fan part cooling, turn off slow down for overhangs, turn off thick bridges internal and external and reduce filament flow to .85 or so. I got some real nice results with ASA like that. When i crack petg i will post again with concrete settings.

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