I’m pretty new to PETG, and have been really struggling with it compared to PLA. My latest print of this part is dimensionally accurate, but I need it to be air tight. It is very much not at the moment.

I have a Flashforge Adventurer 3, so the hot end and nozzle are one interchangeable unit. My higher temp nozzle is 0.6mm. My 0.3mm is only capable of 240. My last print was 0.2mm layers, with the 0.6mm nozzle at 245C. I used 15% overlap on my walls, and in order to keep my nice dimensions I had my cooling fan on.

Anybody have any advice on how to improve the seal? I’m tempted to try more overlap, with random start locations per layer. Do you think if I run it hotter I can get the layers a little thinner? Any advice would be appreciated.

  • @j4k3MEnglish
    9•1 year ago

    Around a year ago Stephan from CNC Kitchen on YT did a bunch of scientific tests to show how to best bond layers and attempt to print without inclusions. Maybe check that out. It requires higher temps and super dialed in squish. Printing perfect PETG requires double the amount of tuning and effort as PLA. It also sucks up moisture to the extreme. Like you can print fine with kinda wet PETG, it will make lots of zits, stringing, and terrible seams. If you want it perfect, the stuff has to be dried to the extreme and printed from a drybox. I hate PETG. I’d rather print any other filament if I can. If I really need to use it, I dry it, but I also manually place every single seam on the inside of my part and in the middle of any back walls. Almost all issues with PETG will occur due to or around seams. If you can hide all of these, the outside of the part can look nice. Like I’ll go into my design and add a tiny chamfered groove in the outer surface if I have no choice and must have an external seam. Just forcing the extrusion anchor inside the part by a few millimeters can help mitigate the issues. All the problems are due to moisture expanding and causing ooze combined with PETG being extremely sticky when molten.

    • DrNeurohax
      3•1 year ago

      I agree. Especially on slowing down the speed.

      A few other things to consider:

      • Backing off the extruder a smidge can help.
      • There’s so much variation in PETG filament between brands that I would do a temp tower, just to be sure. I’ve had “PETG” that worked best @ 235C and 260C.
      • Play with retraction. It looks like that printer has a Bowden setup, so the range of length can vary a bit, but I’ve had success turning retraction off, as well as setting it to 6.5mm. It kinda depends on the geometry and filament heat retention.
      • I try to avoid getting near the printed part during travel - there’s always some little hair that catches the nozzle as it flies by.

      And like others said, coat it with something to fill in the tiny pores. I generally have some thin epoxy lying around for stuff like table tops. You can basically use anything as a colorant in it. It very slightly yellows with UV exposure, but the worst I’ve seen the decent stuff get is similar to a very slightly warm white from an incandescent bulb. A tiny touch of blue should make it weather nicely.

    • @BoxOfFeetOPEnglish
      3•1 year ago

      My issues are definitely around the seams. I thought randomize go the starting points on my layers would help, but it just made the whole part leaky instead of having it localized. I’ll definitely check out that video, thank you!