Prusa PETG poor print  

RE: Prusa PETG poor print

Some of what you are getting is not really "stringing" (small strands of filament being pulled away as the nozzle moves) as "delamination" (printed extrusions being pulled off the underlying layers by tension as the nozzle moves across an inner surface). There are a few things you can try to improve inter-layer adhesion. Try these steps in this order. A combination may yield best results:

1. Reduce speeds. If the nozzle moves too quickly, extrusions don't have time to form a solid bond with the underlying layers. Try reducing speeds with the front knob as a quick test. I'd dial it back 50% as a quick test. If that helps, you've confirmed this is the issue.
2. Increase temps. Hotter temps will allow layers to bond better. Reduce or eliminate cooling if you're using any (esp. with PETG). Increase nozzle temp 5-10C and see if it adversely impacts finish.
3. Reduce layer heights in the impacted areas. Higher layers are printed with increasingly circular cross-section (less "squish"). As heights increase, there may be insufficient contact with underlying layers to get good adhesion.

You may also have issues with overhangs where support might help. Save a 3MF project file with your part & settings, zip it and attach it to a reply for additional suggestions.

RE: Prusa PETG poor print

@bobstro

I second this suggestion to slow  things down. I’m currently fighting a set of models that are giving me endless grief with Prusament PETG and the textured steel sheet. This morning I finally managed to get a good print by slowing speed down to 60% of the stock 0.2 mm quality setting. 

RE: Prusa PETG poor print

I made several speed parameter changes. While did not cure problem completely, is much improved. I have included the 3mf file and couple of pictures in the zip file I am uploading. Any more parameter changes will be helpful. I can't tell if the zip file uploaded correctly. I used the add media option. I am not very familiar with how to use forum.

PrusaJM

RE: Prusa PETG poor print

I too am having a difficult time completing a print using PETG as well.  The trouble that I am having is very similar to the first post.  I have also noticed that when I am printing small parts that are inside of a larger part, during the print one of the smaller parts will be picked up by the nozzle and cause a huge blob on the print head.  When the blob forms the print crashes and makes an even bigger mess.  I have done a bunch of reading and tweaking of settings with some improvement, but not enough to call it good.  Some of the things I have adjusted are:

Print Settings -- Layers and perimeters - Quality - Avoid crossing perimeters - Checked (not checked)
Print Settings -- Layers and perimeters - Advanced - Seam position - Random (Nearest)
Filament Setting -- Filament - Extrusion multiplier -- .9 (from 1)
Filament Setting -- Filament - Extruder - Temperature First Layer -- 240 (from 230)
Filament Setting -- Filament - Extruder - Temperature Other Layers -- 230 (from 240)
Filament Setting -- Filament - Bed - Temperature First Layer -- 90 (from 85)
Filament Setting -- Filament - Bed - Temperature Other Layers -- 90 (from 90)
Filament Setting -- Filament Overrides - Retraction - Lift Z -- .6 (from .2)
Filament Setting -- Filament Overrides - Retraction - Retract on layer change -- checked (not checked)
Filament Setting -- Filament Overrides - Retraction - Wipe while retracting -- checked (not checked)

I have seen other people talk about slowing things down and I am sure which variable to adjust.  Looking at:
Print Settings -- Layers and perimeters - Speed for print moves - I see 10 variables to adjust and more in other sections.

Any other comments or suggestions would be more than welcome.

Thanks for everyone's help in advance.

RE: Prusa PETG poor print

After viewing the way these models came onto the plate when loading your .3MF ,I think you may have been printing these files up side down.

It would explain everything shown in the images you posted above.

Consider flipping them and try again.

Good luck,

Dan

RE: Prusa PETG poor print

By the way "Big John" as I'm pretty sure this is gonna solve your problems, I thought I'd mention I work for cookies.

But really I'd like that flower cutter model my daughter liked it. if you could post it would be much appreciated

RE: Prusa PETG poor print

@dieter-h3

Well, I actually do it the lazy man's way.... 

I don't bother with changing the speed in the settings - as you pointed out just too many fields to worry about.

To generate the GCODE, I leave everything at default values for Generic PETG or Prusament PETG, depending on what brand I'm using.

Then, when the print is starting I change the speed globally to 30% or whatever value you want to set it to by turning the knob on the LCD display. Then after a layer or two, if everything looks good, I turn it back up to 100% (or whatever) the same way.

RE: Prusa PETG poor print

I did print them correctly, I think. They were printed in orientation shown in pictures. I was able to clean them up and use them.

I have been trying to print a food safe box with Prusa PETG with no luck. Tried different speeds, different PETG, different heat settings, all fail. The first layer is balling up. I clean bed with Windex only. I'll try suggestion about changing speed at printer via knob, once I figure out how to get all defaults back. Once bed cooled, the print was VERY hard to remove. Guess because it was so then??

I thought I might have something wrong with printer, but box prints fine using PLA.

The curling was caused when I removed the print from bed. The missing filament and blobs were caused by the print.

And we ate all the cookies 😋 😋 

RE: Prusa PETG poor print

To help with separation put a thin layer of glue stick or Layerneer on while the bed is cold and after the print let the sheet cool down to room temperature. May sound counter intuitive but PETG binds too well to the smooth sheet and the glue stick adds a layer of separation. 

Also, as print bed and nozzle heat up the nozzle reaches target temperature way sooner than the bed and the filament will start oozing out. Make sure that you remove all ooze from the nozzle with needle nose pliers. PETG likes to bind to itself and if there’s anything left on the nozzle it may lead to blobs. 

RE: Prusa PETG poor print

Thanks for the info. Lots to try 😀 .  I had everything working before. Printed several things with PETG with only minor issues. I think the boxes may have too much area in contact with bed. Always something new to learn 🤣 

RE: Prusa PETG poor print

@johnmartin4

Yeah, even with PLA I sometimes have problems with large rectangular objects such as boxes, where the corners like to lift off. Rarely on my MK3S but on my other printers. My usual remedies are to put a brim around the model, use glue stick and/or dial the speed down. But the smooth Prusa sheet usually works like a miracle with just a good rub of IPA.

The textured sheet though, now that’s a whole different story...

RE: Prusa PETG poor print

For the textured sheet with PLA, I've gotten into the habit of putting a dab of the Layerneer Bed Weld in the area of any corners that might have a tendency to separate as well as the areas of any small-footprint supports.  I'm really sold on that stuff.  It's not an alternative to keeping the plates clean, but it sure helps with things that tend to not stick well or pull off of the build plate.

RE: Prusa PETG poor print

@jsw

I recently bought a bottle because I saw you recommending it and it is indeed amazing. Two thumbs up. Also seems to come off a lot easier than glue stick. 

RE: Prusa PETG poor print

I've been using Elmer's washable disappearing purple Glue stick. I bought a 5 pack for $2.39 USD about 2.5 years ago. I'm still using the first tube  and it works perfectly for PETG, ABS and TPE/TPU. the reason one tube lasts so long is because you can get multiple prints from one application. I generally apply it to the ares that the model is going to occupy on the plate, It acts as a release for PETG, ABS and TPE/TPU on my PEI sheets, and In the case of my powder coated textured sheets a suitable bonding agent.

It goes on very thin and disappears, it doesn't leave the high ridges you might experience from the glue that came with your printer. when its time to clean up you just wash it off under warm water with the tips of your fingers and then a quick drying with a paper towel, it comes right off (no elbow grease required), you can then reapply if needed and if you are planning to print PLA on your PEI sheet then just clean it with isopropyl alcohol after the glue is rinsed away.

BTW it works on glass beds also, and any school projects the kids might have going ; )

RE: Prusa PETG poor print

The thing is, with the Layerneer you don't tend to use as much of it as you do the glue stick.

RE: Prusa PETG poor print

@ Big John

we ate all the cookies 😋 😋

That's the story of my life.