Need help with PCTG

[Rocketzx1]

Hello.

I bought a roll of PCTG to try as an improved version of PETG, mainly for the higher impact resistance for some 3D printed rc parts.

I found a bed liner print for the TRX4 Sport body, of which I've painted one up for my Tekno MT48 2.0, and thought the bed liner and a roll cage would be a fun little project to add a bit more to the truck.

I did some test prints after drying the PCTG for 8 hours @ 55c, and they came out great. Flexibility of this filament is impressive.

And now I am having issues with what appear to be burnt/brown spots on my prints.

I have an Anycubic Kobra S1, on the latest firmware for both the printer and ACE, I'm using the profile for PCTG made by 3D-Fuel, Hardened Steel hot end from Anycubic @ 0.4mm, stock PEI plate that came with the printer. I've imported the settings for the PCTG into Anycubic SLicer Next with no issues, made no changes to the initial profile for the PCTG.

What I have tried is lowering nozzle temps by 5c each time, from the stock 270c down to 250c, I've lowered print speeds, I've dropped acceleration speeds by half, no change.

Do any of you have any ideas?

 

[Guest D]

Could it be contamination?

 

[Rocketzx1]

Could it be contamination?

I wouldn't think so, as I always extrude some filament before I do a print to run out what little bit is left from the previous print.

 

[Guest D]

Did you try to increase print speed?

Weird because it's not really consistent.

 

[Rocketzx1]

I have not increased print speed, current settings are 50mm/s first layer, 80mm/s first layer infill, outer wall is 200mm/s, inner wall is 300mm/s, sparse infill is 270mm/s, internal solid infill is 250mm/s, top surface is 200mm/s, gap infill is 250mm/s.

 

[HPIguy]

Given the rough look of the print, and what looks like nozzle drag marks, it looks like your Z offset is too low to me. You will need to calibrate and create a profile for each filament you use.

 

[Rocketzx1]

Given the rough look of the print, and what looks like nozzle drag marks, it looks like your Z offset is too low to me. You will need to calibrate and create a profile for each filament you use.

I have a profile made specifically for PCTG from the filament manufacturer, 3D-Pro. I took the file straight off their website. I have ran an entire recalibration on my printer, reseated the hotend, made sure there is no filament leaking out of the heatbreak from the top or where the nozzle screws in, I've lowered acceleration speeds across the board by half, as instructed to do by 3D-Fuel.

 

[HPIguy]

I have a profile made specifically for PCTG from the filament manufacturer, 3D-Pro. I took the file straight off their website. I have ran an entire recalibration on my printer, reseated the hotend, made sure there is no filament leaking out of the heatbreak from the top or where the nozzle screws in, I've lowered acceleration speeds across the board by half, as instructed to do by 3D-Fuel.

Straight off their website isn't for your specific printer that you own though. My slicer has presets for my specific filament, and model of printer, but I still get much better results if I dial my actual printer and filament that are in my man cave. Tolerances are a thing, and not every printer, nor every roll of filament is going to 100% identical. It's the only thing I can think of that would cause the rough looking surface, and the burn and drag marks. But, as always, I can be wrong.

 

[xjtorc]

Judging by the burns, stringing, and the extreme gloss…I’m guessing your nozzle is too hot.

Print a first layer square calibration first. Lock in your Z height. It could be a smidge low.

Then print a temp tower and see what it tells you.

Printers are amazing nowadays, leaps and bounds beyond what they were just 5 years ago. But they all do still require hands on calibration to print their best.

 

[WickedFog]

Those dark spots are usually filament clinging to the nozzle, getting burned, and redepositing into your print. Lift your head, run some filament out and watch for the filament curling. Sometimes a bit of filament gets crystalized inside the nozzle and causes the filament to try to curl up into your nozzle. It later gets pulled off after over-cooking.

 

[RetroThutmose]

Those dark spots are usually filament clinging to the nozzle, getting burned, and redepositing into your print. Lift your head, run some filament out and watch for the filament curling. Sometimes a bit of filament gets crystalized inside the nozzle and causes the filament to try to curl up into your nozzle. It later gets pulled off after over-cooking.

yeah, these just look like boogers to me. they get stuck to the nozzle and usually fall off randomly. in some cases they have ruined entire prints for me by falling off, getting solid and then hitting the nozzle.

 

[Guest D]

yeah, these just look like boogers to me. they get stuck to the nozzle and usually fall off randomly. in some cases they have ruined entire prints for me by falling off, getting solid and then hitting the nozzle.

That sucks, I haven't had that happen yet.

 

[RetroThutmose]

That sucks, I haven't had that happen yet.

i only have issues with them with petg, i have not tried pctg yet. but looks like it prints very similarly.

 

[Rocketzx1]

Turns out I’m dumb af, because I pulled the hardened steel hotend out and there is globs of filament all over the top where it did leak out and worked its way between the heatbreak and silicone sleeve, and goobered up around the nozzle.

When I first looked last week, there wasn’t any build up of filament that had leaked out on the top of the heatbreak. The burn marks would have been from the nozzle just scraping the print a tiny bit.

I appreciate the help, I will be taking all of your suggestions and tips and use them to have a better printing experience,
especially @HPIguy advice.

I’ve contacted Anycubic for a replacement hotend, I’ll keep you guys updated!

 

[Rocketzx1]

Been almost 2 months since my last reply, mostly because of life.

Anycubic sent a new hotend no questions asked, which was cool. I haven't used it yet, I just reinstalled the stock brass hotend and have been using that.

I returned my first spool of PCTG and was sent a replacement spool of PCTG in white. I dried it for 10 hours before I even loaded it into my Ace Pro, and gave it a go. I printed the Swoop Wing for the mk4 Supra Proline body.

Results were not terrible but not great either. Blobs and stringing out of the print, uneven in the middle.

I printed the same model in red/blue pla and it came out great with stock Anycubic pla settings.

I bought a new roll of 3D Fuel PCTG in blue, used 3D Fuels newest print profile for this new spool of blue PCTG, printed great.

 

[Doom!]

Glad you found a brand that worked out for you. That's a significant difference in quality.

 

[WickedFog]

Been almost 2 months since my last reply, mostly because of life.

Anycubic sent a new hotend no questions asked, which was cool. I haven't used it yet, I just reinstalled the stock brass hotend and have been using that.

I returned my first spool of PCTG and was sent a replacement spool of PCTG in white. I dried it for 10 hours before I even loaded it into my Ace Pro, and gave it a go. I printed the Swoop Wing for the mk4 Supra Proline body.

Results were not terrible but not great either. Blobs and stringing out of the print, uneven in the middle.

I printed the same model in red/blue pla and it came out great with stock Anycubic pla settings.

I bought a new roll of 3D Fuel PCTG in blue, used 3D Fuels newest print profile for this new spool of blue PCTG, printed great.

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Those don't look too bad. You have what nearly every "guru" on YouBoob and Fakebook would call "Z Axis Wobble" or "Layer Shifting", which is just asinine.

Check the tension on your belt(s) or whatever controls your X and Y axis. You likely have the slightest bit of play in the system.

You can easily verify this by looking at the verification screen of your print and finding these locations. Single block through the animation of the print and see if your head travels the opposite direction around the perimeter at these heights. If so, you have play in X, Y, or both. Not bad though.

But you don't even have to. That hole on the side is definitely reversing toolpath direction, and based on that, you definitely have a little play somewhere

You are also printing your infill in "Concentric" mode. This basically spirals from inside or outside around the perimeter, morphing the path from the inner shape to the outer shape.

Not something I recommend using much unless you are going fo⁸ a specific look, like you're 3d printing a circle. But for this wing, it probably looks pretty good on top of the wing.

But those little triangular gaps in what I believe is your brim is because your nozzle is too wide to print there as that toolpath shrinks to nothing. In my slicer, there is a setting called "Single Extrusion Fill" and an "Allowed Overlap" setting that allows the slicer to add short paths in those empty triangular spots to fill those voids.

I want to show you something, which is why you gotta pay attention to who you get advice from out there in La La land. Now this applies to a gantry machine, instesd if a cube like yours... but still relavant...

Let me go send Google Gemini a question...

Now watch me school a super computer

Gemini then replied, and is spot on in the description of that "diagnosis".

To verify slop is your issue...

Let me know if this makes sense or if you need me to confuse you further

In the end, trial and error is going to get you printing like a pro. But the very first things I do with any new machine is check everything is set correctly. No backlash in belts, rollers, fittings, etc and all have proper tension. Then square the machine with indicators, 1-2-3 blocks, 2-4-6 blocks - whatever it takes. Start at the base making sure your bed is flat to the world, and work your way up from there. All vertical assemblies are indeed vertical and square to bed. You would be surprised at how many guys I've seen actually make their machine worse trying to adjust things lol.

 

[Rocketzx1]

Glad you found a brand that worked out for you. That's a significant difference in quality.

Well that was half the problem, the first 2 rolls of white PCTG came from 3D Fuel as well. Must have been a bad batch.

 

[WickedFog]

Well that was half the problem, the first 2 rolls of white PCTG came from 3D Fuel as well. Must have been a bad batch.

I have gone through at least a couple hundred rolls of filament. I have only ever had 1 roll that I can say may have been bad. And I still am not 100% certain on that.
My filament gets opened, put on a printer, and stays there, sometimes for months until it's used up. I have never one time put filament in the oven, a dryer box, or anything else to try to get a roll to print. They just print.

I know filament can get brittle if left out. But once I get 3 or 4 coils into a half used roll... it's golden. Send me one of those rolls. I'll tell you what's wrong with it

Rule of thumb - and I have had way more than my share of weird ass problems that I could have just blamed the filament, the neighbor's dog, etc. But it is almost always some stupid little change that makes it work, or operator error, or that particular filament just runs different.

Here's a good one. I had my original CR10 setup as perfect as perfect gets. It was printing flawlessly, for days at a time. Then one day I checked my Octoprint from work and it was burrying itself in black spaghetti. I shut it down and when I got home I saw a perfect print 10mm high, then spaghetti, then it somehow reattached itself to the part, printed beautifully, then spaghetti again.

I spent days trying to figure that out. Then I watched the video. It was printing fine, then I noticed something. The curtain waved in the background. I went to spaghetti creation number 2. Right before it failed again, the curtain waved a little.

The ambient temp had raised and my AC kicked on, blowing cold air at my printer. Back then, nobody mentioned that kinda chit happening lol

 

[Rocketzx1]

Those don't look too bad. You have what nearly every "guru" on YouBoob and Fakebook would call "Z Axis Wobble" or "Layer Shifting", which is just asinine.

Check the tension on your belt(s) or whatever controls your X and Y axis. You likely have the slightest bit of play in the system.
View attachment 272201

You can easily verify this by looking at the verification screen of your print and finding these locations. Single block through the animation of the print and see if your head travels the opposite direction around the perimeter at these heights. If so, you have play in X, Y, or both. Not bad though.

But you don't even have to. That hole on the side is definitely reversing toolpath direction, and based on that, you definitely have a little play somewhere

You are also printing your infill in "Concentric" mode. This basically spirals from inside or outside around the perimeter, morphing the path from the inner shape to the outer shape.

Not something I recommend using much unless you are going fo⁸ a specific look, like you're 3d printing a circle. But for this wing, it probably looks pretty good on top of the wing.

But those little triangular gaps in what I believe is your brim is because your nozzle is too wide to print there as that toolpath shrinks to nothing. In my slicer, there is a setting called "Single Extrusion Fill" and an "Allowed Overlap" setting that allows the slicer to add short paths in those empty triangular spots to fill those voids.

I want to show you something, which is why you gotta pay attention to who you get advice from out there in La La land. Now this applies to a gantry machine, instesd if a cube like yours... but still relavant...

Let me go send Google Gemini a question...
View attachment 272202

Now watch me school a super computer

View attachment 272203

Gemini then replied, and is spot on in the description of that "diagnosis".
View attachment 272204

To verify slop is your issue...
View attachment 272205

Let me know if this makes sense or if you need me to confuse you further

In the end, trial and error is going to get you printing like a pro. But the very first things I do with any new machine is check everything is set correctly. No backlash in belts, rollers, fittings, etc and all have proper tension. Then square the machine with indicators, 1-2-3 blocks, 2-4-6 blocks - whatever it takes. Start at the base making sure your bed is flat to the world, and work your way up from there. All vertical assemblies are indeed vertical and square to bed. You would be surprised at how many guys I've seen actually make their machine worse trying to adjust things lol.

Holy wall of text batman, too early for this much info I’m jk

It all makes sense, I’ll have to find time to try and tinker some more with dialing in the printer. The print bed, unless I replace it with aftermarket, is as flat as I’m going to get right now.

Right now though, other than printing the white PCTG, prints are good and I’m good with that lol