PCTG strings and overhangs

[Bryan Murphy]

I've been experimenting with 3D-Fuel PCTG lately.  I like it, but I still have some challenges.

First, regarding stringing.  I was getting a lot of wispy stringing and blobbing until I lowered the temp to 255 (recommended range 250 to 270).  That works better, but I still get the long spiky strings at seams.  Any recommendations on how to minimize those?

And I'm still struggling with overlangs and layer adhesion.  I'd like to increase the temp to help with the layer adhesion but of course that will make stringing and overhangs worse.  Any recommendations on how to address that?  I currently have fans running at 10%-20% for most of the print, but tried cranking the fan to 100% for overhangs.  I can't quite tell yet what impact that's having.

Centauri Carbon, enclosed printer, chamber temp is usually around 35ºC and bed temps at 80.

Thanks,
Bryan

[Kurt Gluck]

I really hate to say it but, have you considered drying the stuff?

Kurt-A

[Kurt The 3D Printer GUY!!]

Yo there My buddy Kurt. Generally speaking - some printing problems are indeed solved by drying filament. I did a LOT of printing of PCTG at Essentium - and I do believe that may be a good suggestion. 

Butt - that being said - you will hear Andy MANY Times in the podcast state that drying filament is NOT always the solution to these types of problems. 

All this being said - Bryan - I am hoping that my good buddy from 3D-Fuel, the CEO - will respond back to this thread! I am sure he will. Too bad you didn't write "3D-Fuel" in the Subject line as an even stronger callout to your request for help.

I'm also going to do something else - to help prompt some more feedback to this thread of yours. So - Hold Tight sir!

-K

[Bryan Murphy]

I'll dry it again, I know that won't hurt any, but I'm super diligent about keeping things dry.  I doubt that's the cause.

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[Jody Harris]

Does 3D Fuel have a profile for your printer? If that's not what you're starting with, you should. The 3D Fuel profile for the Core One is perfect. 

-j

Think carefully

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[3D Printing Tips and Tricks]

Stringing can be related to moisture, but If it’s happening after the outer layers of filament on the spool, it’s more likely another issue. What size nozzle? Retraction settings?

[Bryan Murphy]

Yes I started with their profile.

[Bryan Murphy]

Nothing exotic for the retraction settings, pretty normal stuff:

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[3D Printing Tips and Tricks]

Increase  length to 1.2mm

Increase speed to 40.

Retract on layer change should be on.

Also try wipe while retracting… make the retract amount 5%.

[Bryan Murphy]

I updated the settings per your suggestions (as well as dried the filament again).  It removed the protrusions at the seams and there's no nuisance zitting/blobbing but as you can see based on the picture surface quality still leaves a lot to be desired.

I also bumped the temp up from 250º to 270º and slowed the printer down slightly (normal => quiet mode).  I watched it while it was printing and the foundation layers were way too matte for this type of filament. 

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[Kurt Gluck]

Bryan

Take a look at this video, see if it helps: https://youtu.be/S6_xnzt9YPU

Kurt-A

Sent from my iPad

On Oct 21, 2025, at 1:06 PM, Bryan Murphy <bmurp...@gmail.com> wrote:



I updated the settings per your suggestions (as well as dried the filament again).  It removed the protrusions at the seams and there's no nuisance zitting/blobbing but as you can see based on the picture surface quality still leaves a lot to be desired.

I also bumped the temp up from 250º to 270º and slowed the printer down slightly (normal => quiet mode).  I watched it while it was printing and the foundation layers were way too matte for this type of filament. 

<image.png>

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[3D Printing Tips and Tricks]

This is PCTG. Why are you going hotter? PCTG is more like PET then PC. I would have started at 235C. You could be getting foaming.

[Bryan Murphy]

I saw that yesterday but had to try Andy's recommendations first.  I'll definitely take it into account for future iterations.

[Bryan Murphy]

3d-Fuel recommends 260-270.  I was getting poor layer adhesion @ 250 previously:

https://www.3dfuel.com/blogs/news/how-to-get-the-best-printing-experience-with-pro-pctg

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[Bryan Murphy]

Andy, if you are printing PCTG @ 235, how slow would you print it?

[Bryan Murphy]

Over-retracting is where I was already leaning.  It didn't seem like it was under extruding when I ran the flow rate tests, but I can play around with that as well.  

I printed the same model twice with Elegoo PETG PRO the other day and the prints are absolutely flawless.  I'm not convinced my PCTG settings are even close to ready.

On Tue, Oct 21, 2025 at 1:08 PM Jody Harris <jha...@harrisdev.com> wrote:

It looks to me like you're getting some gapping. In my experience, this is usually caused by over-retracting and getting air bubbles into the filament path.

I'm really surprised how poorly the 3D Fuel profile is working for you.

Do you have another spool in a different color of 3D Fuel PCTG? I know I ended up with one spool of 3D Fuel PCTC that underextruded by 18% (!). I haven't had that issue with any of my other spools.

-J

Think carefully

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[3D Printing Tips and Tricks]

Last time I printed PCTG I simply used the same settings as PETG and I always start with 235c. I also lower the speed of the downward cooling fan.

[Kurt The 3D Printer GUY!!]

Darn - I wrote a whole reply - was just about to send - and BOOM - the power went out in my whole complex.

John @ 3D Fuel has had his hands full lately. Maybe reach out directly to Support at 3D Fuel about your issues. I want to see US manufacturers compete with all the foreign filament makers! So - yeah - I feel bad for your filament issues!!!

-K

[Bryan Murphy]

I made some progress.  I have the first print I would consider acceptable.  There's a bit of wispy stringing inside and at the seam but it's manageable.  The seam isn't amazing but it's again passable (at least for this model).  There's no blobs, zits, or noodles anywhere which is a huge improvement over where I was a week or two ago.

I started with the same settings I used per Andy's suggestions (which were the only changes from the 3D-Fuel stock profile), lowered temp to 265º, lowered retraction to 0.4mm and set max flow rate to 3 mm/s.  I figured that setting the max flow rate was the most straightforward way to slow things down.

It seems to have worked.

I'm going to play with pressure advance and temp a little more to see if I can shore up the seam and further minimize the wispy stringing.  I finally feel like I'm moving in the right direction!

[Kurt The 3D Printer GUY!!]

Hey Bryan - I am really Thrilled to see you're having more success!!! I was bummed to hear of your problems with your 3D Fuel PCTG. 

Honestly - I gotta get crackin' soon to print PCTG on my own Elegoo Carbon - as I have a need for some parts that are a bit stronger - something that may eventually be a prototype that I launch via KickStarter! But, yeah - I really want to truly support US manufacturers like 3D Fuel (especially as I was tied to them via Essentium). 

Now that I'm done moving (more on that in another posting) - I really want to get back to crankin' out some Print jobs! 

IN that vein - tonight I am printing up my Toy Rocket type design - partially to see it re-printed again and how well it does on my Carbon. Partially as a replacement for the last one that was printed on a Bambu CX1 in multi-colors - that sadly got broken slightly after my last move. But, yeah - partially to keep pushing my Elegoo and see some Great results on it!

For the hell of it - the Rocket design is attached here. Deal is - it can be printed with NO Supports - and NO Infill - that is how I designed it!

-Kurt

P.S. Bryan - if you decide to print it in PCTG - I would LOVE to see the print!