PETG support layer adhesion problems
I've done a lot of printing in PETG, I print almost exclusively in it, so I consider myself reasonably experienced at PETG printing. However, I've recently been having lots of problems with supports. The first layer of the support goes down fine -- bed adhesion is fine. However, somewhere further up (in the most recent failure today, the second layer, but it in other prints it has been higher), something goes wrong. The support layer doesn't stick to the one below it, PETG starts getting all balled up on the sock, and then at some point it gets dumped on the print and causes a head crash.
I already scraped the last failure off the bed surface, so I don't have a picture to post. If you can envision the model printing about four or five layers just fine, but the supports having only the first layer down with maybe a few zig-zag lines of the second second layer, that's what it would look like. The model itself doesn't have a layer adhesion problem, but the support structures do.
Last time I was fighting this, I reduced the support material speed (was originally running at 50mm/s; decreased to 30mm/s). Could go lower if I need to, but just don't know if that will resolve it or if something else is wrong.
Any advice appreciated.
RE: PETG support layer adhesion problems
Sounds a bit like interlayer adhesion issues, running the nozzle a bit hotter, or slowing the print fan might help. Or increase support width to add a bit more mass for a better contact surface.
RE: PETG support layer adhesion problems
Strange thing is, there's no layer adhesion problems on the model itself. Only on the supports. That leads me to think it's not temperature or speed.
Hmm, maybe I will try increasing the support width. This would be Print Settings -> Advanced -> Extrusion Width -> Support Material in Slicer? It's currently set at 0.35mm versus the default of 0.45mm for most everything else.
Scott
RE: PETG support layer adhesion problems
Just increase nozzle temp. Make it more of a liquid
RE: PETG support layer adhesion problems
[...] Hmm, maybe I will try increasing the support width. This would be Print Settings -> Advanced -> Extrusion Width -> Support Material in Slicer? It's currently set at 0.35mm versus the default of 0.45mm for most everything else.
Definitely worth a try. While you can get extrusions thinner than your nozzle width, the results are very likely to be less reliable than those using somewhere between 100 and 120% of nozzle width. The fact that the main print is fine and only the supports are weak in particular would lead me to try this option.
RE: PETG support layer adhesion problems
Note: FWIW, I set my extrusion widths to 0 in PrusaSlicer and let it figure 'em out. This works for me with a variety of nozzle sizes and filament types. YMMV.
RE: PETG support layer adhesion problems
Does it look like this?
I just had this happen for the first time yesterday. I printed a ton of supports in PETG in the past and never had an issue, but I haven't printed anything with supports in the past ~3 months. Could it be a regression in Plicer or firmware or printer/filament settings? Have there been some changes to how supports are handled recently?
RE: PETG support layer adhesion problems
typically the supports print faster than the rest of the job - look at "Print Settings"/"Speed"/"support material"
RE: PETG support layer adhesion problems
Wondering if anyone found a resolution to this? My printer is having the same problems. The first layer goes down fine, then the first layer of support on top ziggy base layer doesn't stick and is intermittent. Eventually things even out with the supports, but eventually the support breaks free of the first layer, ruining the print. I've printed many things in PETG and never had this problem. Seems like maybe a new software problem?
RE: PETG support layer adhesion problems
I have found with several PETG prints that use a lot of support material is that you have to print them hotter than normal. like 255. It seems like otherwise they supports get dragged along a bit. I found this with my recent hannibal mask print where there was a lot of support material. The hotter temp made things happy.
RE: PETG support layer adhesion problems
In case anyone else has this issue, I solved it by following the advice in this thread. I increased the support extrusion width from 0.35 to 0.45, and increased my temperature to 245 for the whole print (usually do petg at 240). Just completed a 5 color, 24 hour MMU2S print with 0 issues or interventions
RE: PETG support layer adhesion problems
Glad you got it working!