Best settings for Sunlu PETG

Hi,

I’ve just got 2 spools of Sunlu PETG and wonder if somebody is experienced with the filament.

The default temperature in Bambu Studio is 255 degrees while Sunlu recommends 220-250.

I have to print the whole platform with small parts, maybe you might point me out what temperature is better to use or to start with?

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I dont have sunlu PETG, but I have other PETG. The recommended temperature is most likely set for slower printers we all had 1-3 years ago. These printed slower which gave the filament more time to heat up. So I usually set the temp. at 5-10 celsius above the max rated by the manufacturer as bambu lab printers are much quicker.

Thanks, understood, will try to start with the default 255C in Bambu Studio.

Well as you probably know, there is no quick answer. No matter what anyone tells you or you may have read, this is not a question that can be answered definitively. There are too many variables that will affect the answer. The first of which is what do you want to achieve. Are you looking to use PETG for one of its specific properties such as Higher Temps, UV resistance etc. Or are you looking for more dimensional accuracy since you’re printing parts? Also, the humidity in your environment will also play a role as well as when the filament was packaged at the plant. If your date codes on the box are months apart, you could have two different moisture contents.

To save money on wasted prints, you’ll want to tune in a profile. This goes true for even the standard profiles that Bambu supplies, while good, aren’t necessarily suitable for all use-cases even with their filaments. I’ve found that I can generally get, smoother, more accurate and faster prints if I go through the hassle of tuning the filament profile.

Ironically, I have some Sunlu PETG arriving today because it was on an Amazon flash deal yesterday. So I may be able to give you a more specific answer later in the week after I tune my profile.

Here’s what I do with every new filament when I use it for the first time.

  1. Weigh it and write that weight on the spool itself. Then when it’s empty, weigh it again and write the weight of the spool and mark it as TARE and either keep the spool on hand for a record or maintain a log in a spreadsheet. While I don’t always dry my filament, with PETG which can be hydrophilic, if my initial tests show filament problems, I’ll dry it and then do a before an after weight. If you let’s say have a partial spool and weigh it before drying and then weigh it after, you’ll know how much water content was in it. Remember, 1g=1cc=1ml of water.

  2. Run a temperature tower(Up to 30 minutes depending on the range you dial in but worth the effort)

  3. Run a Pressure Advance test using the new PA Pattern which is baked into Orca.(10 minutes)

  4. Then I run a Max flow rate test to determine how far I can push the filament.(optional and I usually watch the test and cut it short when it’s obvious that I got to the filament limit)

  5. Last, I run a tolerance test using any number of tolerance testing models including the one baked into Orca, but the one I find the best is one that I created on my own using simple outer and inner rectangles. I then measure the tolerances based on what I designed in CAD and then dial-in the X-Y offset for both hole and contour.

If you’re building parts, then dimensional accuracy test is most important of all. For that, you can skip right to step 4.

This whole process will take a couple of hours the first couple of times you do it until you master it and learn the printer interface. Now I can do it in under an hour unattended just because I now know exactly what I am looking for. But it takes patience to learn how to do it and watching a few YouTube videos on Orca Calibration.

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My first attempts at printing PETG were with Sunlu filament, using both the Bambu and the Sunlu recommendations. It didn’t stick to the plate very well and was stringing badly. The temperature tower I printed with Sunlu PETG (red) made it pretty clear I needed to print at 260 °C. A higher temperature than Bambu suggests, and higher than Sunlu suggests, but that is the temperature that works best (for me). Inland silver PETG also likes 260°, but Inland black PETG prints better (for me) at 250°. Further testing for the best flow rate, pressure advance, and maximum volumetric speed for each filament improved my prints even more. Those tests provided settings that were all slightly different from the recommended settings.

I think the manufacturer suggestions may provide a good starting point, but you really need to take the time to calibrate each new filament using your printer in your environment if you want optimal results.

Thank you @Olias @lkraus, you’ve finally persuaded me to install Orca and I liked it very much, especially for having PA in FIlament properties (where it should be imho :slight_smile:) and a wider range of calibrations.

Max flow calibration was quite useful for me, the default value in 12mm3/sec is quite low for Sunlu at 255 deg, it turned out that 25 and even 30 works fine with no issues.
I set it to a “safe” value in 20 which improved the printing time by 25%.

Regarding the temperature tower, it’s a bit more difficult to use it compared to Flying bear printers e.g. since a wide range of temperatures looks fine :slight_smile:

One more point that confused me a bit is that there is more stringing in 230-240 range than for 255 degrees.

It’s also difficult to say that the printing results at 255 look bad, but I have some kind of “feeling” that they are more “fragile” than for 235 e.g.
Perhaps it’s due to “temperature destruction” of the filament.

I couldn’t find more information on the Internet, but while doing the crash testing it seems that the parts printed at 255 are cracked easier.

Maybe you’ve faced the issue as well?

Your findings are consistent with much of what you saw on the Internet and also what my experience was.

I’ve come to the conclusion that there is no defined answer on the topic of the “ideal” temperature in as much as it is a range of temperatures where the tradeoff is a triangle drawn between stringiness, layer lines and strength.

The only other tip I might share that I saw recently on a YouTube video was a very unscientific approach that the YouTuber admitted was unscientific but better than nothing at all. What he did was to take a small screwdriver and break off the tip of the tiny tower inside of the temp tower. Based on the “feel” that would let him know what temperature produced a stronger bond. Now Stefan over at CNC kitchen uses his DIY strength meter and that is a lot more scientific but I mean C’mon now, how anal-retentive can one be? This is supposed to be fun not work. Nevertheless, I love Stefan’s videos because of the fact that he goes that extra mile that I just simply won’t do.

Here’s a tower that I ran last night for Sunlu Transparent PETG. These are the tips that the YouTuber said to “feel” the breaking point to gauge relative strength. Didn’t work for me, I guess my fingers aren’t calibrated for force. :yum:

But if you look at both ends of the temp spectrum on that one tower, all it shows is that this particular PETG is going to string at either end of the Spectrum. The MFG calls out 220-250°C. Well to me they look like cr@p at both ends so needless to say, I’m underwhelmed and I have to resign myself to stringiness. Now others will quickly point out that I could mess with the retraction settings. Indeed I could and waste 5 hours of my life with only marginal benefits.

Look at these two closeups and you tell me if they look very different. These were done at a 0.20 layer height. Like I said, underwhelming results.

I’ve been using Sunlu PETG on my Ender 3 Pro & my SV06’s for awhile now.
I haven’t tried yet on the Bambu because my A1 Mini is on pre-order.
For me… 235* works well, so this will be my start point in the A1 Mini once it arrives.
And yes, I will also do a temp tower.

Yeah, I have the same thoughts and observations. It seems there is no “optimal” temperature" for fast printers and it should be chosen depending on the kind of job (is it a small/big object or many objects, etc.).

So far I stopped at the idea of printing several test parts simultaneously and look at their surface.
If it looks matte at least somewhere, increase the temperature by 5 degrees until glance is everywhere. Thereafter just add +5 or +10 more degrees and do some stress/crash testing for sure.

I’ve printed 4 accessories today with Sunlu PETG & I can say that 235* has worked out fine for me.
Don’t think I’m going to bother doing a temp tower.

Thank you for sharing your experience.

I recently bought 5.5kg of Jayo PETG in black (which as far as I understand also Sunlu).

Print quality is good, but I have an unusual problem with the adhesion of the first layer. It sticks far too well and I can hardly get it off the plate :man_shrugging:.

What I’ve done so far:

  • Created a custom filament based on Bambu PETG and then Generic PETG
  • Calibrated flow dynamics (k = 0,2) and flow rate (flow ratio = 0,95)
  • Temperature was lowered from 255 to 235 degrees (slight improvemet)
  • Increased a max volumetcric speed to 20 mm³/s after test in Orca Slicer.

Does anyone have an idea what I could change? I would be grateful for any advice :pray:

Kudos to you for making that effort but don’t waste your time trying to calibrate for stiction issues with PETG. That’s not where you will find the solution. There’s a far simpler method even when using a textured PEI plate.

It may seem counterintuitive but try using glue. Glue helps with adhesion but it also serves as release agent between the plate and the filament. Don’t waste your money on expensive glues either, I’ve got a shelf full of them including Bambu liquid glue. Yes, they work well but so does glue stick.

This

and this

Are the same stuff and are made in the same factory. They even taste the same. :yum: Yes, both are non-toxic and are safe to use around young school children who put everything in their mouth. One trick that a member posted here is apply the glue and then take a “Wet” sponge, not a damp sponge, and smear the glue to get and even coating. I’ve tried that and it works well. One guy even had a applicator you can print that does this. I haven’t tested it myself though but the principle seems sound.

So what’s the difference between the two? Price!!!

But here’s my secret weapon that is not a secret, this is bringing back and oldy but a goody from the glass plate printing days of a few years ago, it’s my favorite for PETG and PC on a smooth plate:

It goes on thin and washes off with dish soap. Use multiple coats as if it were like spray paint, 3 thin coats should last between 5-8 prints before needing to reapply. Don’t make the mistake of putting it on too heavy, it just makes for an uneven surface that will ruin the appearance of the bed side of the print. Less is more in this case.

And don’t buy it online, it’s one of the few things that’s half the price in your local store as opposed to Amazon. I pay $4/11oz can.

Hi Olias,

wow, thank you very much for a quick and such a detailed answer.

This is actually a controversial solution: More glue to reduce adhesion :grin:
Of course it makes sense and sometimes you can just fight fire with fire :+1:

I immediately discovered that the proposed products are not sold on the German market, but we have dirt-cheap glue sticks from Tesa. They are also water-soluble and suitable for kids.


I borrow some from my daughter and will try it out :crazy_face:.

That glue is exactly what I am talking about. It uses the exact same formula just under a European brand. You can tell by the non-toxic label and the exact same dispenser.

petg i always have a hard time with

From Sunlu or do you mean PETG itself?
What can you recommend instead?

My SunLu PETG print on 240 / 70, print speed using Gen PETG setting.
Also fan on 30 min 60 max, no fan on first 5 layer.

3DLAC…no way in hell.

The best that worked for me was 260 for some reason. I have the chamber fan off and the door open. Prints very good with little stringing and high quality. I feel like this might be an exception.