Things you should know about PETG


PETG or, more widely speaking, the range of
copolyesters! It’s like PLA and ABS had a lovechild with
all the best bits from either one. Copolyesters have a good mix of properties
and has become my personal favorite, but there are some things it can’t do or will need
extra tuning for. Let’s go through those! [Intro]
There is a bit of confusion around what you should call these materials – is it PET, PETG,
Copolyester or CPE? Well, pretty much only Ultimaker calls them
CPE, which is just a fancy abbreviation for CoPolyEster. Many manufacturers have their own brand names
for various types of copolyesters, be it Colorfabb XT, HT or NGEN, Taulman T-Glase or simply
PETG. PET itself, or Polyethylene terephthalate,
is actually not what you’ll typically 3D print, that would be PETG or the glycol-modified
version of PET. The glycol content keeps the plastic from
crystallizing, making it a bit softer, more chewy and having it melt at a lower temperature
– pretty much ideal for 3D printing on the common machines. PETG print at around 230°C, pure PET at 260°C
or more. Aside from that fundamental difference, filament
producers can also modify the plastic to have different properties for how they perform
while being printed or in the finished printed part. No two PETG materials are going to be exactly
the same, but typically, they’re pretty close when it comes to how they need to be
printed or how the parts will behave. Ok, so how do these need to be printed? Well, for a base tune, grab a PLA profile
you know works for you – or simply your slicer’s default profile – then reduce the part cooling
fan speed a bit, 20 to 50% work well on most of my printers and adjust the temperature
to match what your filament manufacturer suggests. If there’s no recommended temperature, try
230°C and increase it if you see bad layer adhesion or extruder jams or decrease if you
see excessive stringing or curling or other overheating artifacts. On the topic of stringing, most PETGs will
want to string quite a bit because even the molten PETG still doesn’t easily tear, but
will keep pulling that fine string out of the nozzle. It’s a good idea to increase the retract
length by a bit even before your first print, maybe add a millimeter for a direct extruder
and two or three for a bowden. Of you still get strings, you either have
the option of just burning them off with a hot air gun or tuning your printer’s retraction
even further. But you can’t just increase retraction length
like crazy because you’ll end up with blobs instead. What you should into is the retraction speed
settings – try a slightly faster or slower one and it might just be that last piece of
the puzzle to help you get a clean print. What’s always going to help with both stringing
and blobbing is increasing the travel speed between retracts. Travel moves should always be as fast as your
printer can handle, because it’s going to give the hotend as little of a chance of oozing
and going out of the intended plastic flow situation as possible if that makes sense. Your printer’s firmware should know how
fast it can reliably go, so you can actually set the travel speed on your slicer to some
obscene value and let your printer handle the rest. One more note about printing copolyesters:
Whatever you do, don’t print them directly onto glass. Even though it’s kinda hard to stick copolyester
parts together when you actually want them to stick, they will actually fuse to some
glass print surfaces and take chunks out when you try to remove them. PEI and other films are a similar story, so
I’d always recommend using some extra layer of adhesive on top. With those base settings, PETGs and other
similar copolyester materials should easily make for clean, strong and attractive prints. So what do you use it for? Well, anything, really. PETGs can do most things a PLA would be able
to do when it comes to printing detailed parts or larger ones without warping too much. It also has many of the upsides of ABS like
being reasonably temperature resistant up to around 70° or 80°C, which is a bit lower
than ABS; but still good enough for many parts that you’d use with motors or electronics. Prusa even uses them for everything on the
MK3 now. PETGs are also really strong and came out
with consistently impressive results in the filaween tests, but their strength, even though
it is good, I feel is a bit less predictable than other materials because some copolyester
prints like to shatter instead of gradually failing. What can make this behavior much worse is
when you use “wet” PETG – through a process called “hydrolysis”, the water steaming
up as the plastic gets heated will essentially tear apart the polymer chains and make the
plastic more brittle – so keep it dry and if you feel like your spool of filament has
been degraded, chuck it in the oven at 60°C for an hour or two. Copolyesters also come with the huge benefit
of being really clear and transparent if, of course, you get the transparent versions. With the right settings, you can get some
amazing looking parts out of it! Just like ABS, you can use metalworking tools
with PETG prints no problem, but painting or gluing parts can be a bit tricky. If you ever tried to glue or paint a plastic
water bottle, you’ll know that nothing sticks to this stuff. If you need to connect two Copolyester parts,
there are some options for solvent-welding, but they are some pretty nasty substances
involved. What the company 3M recommends is a few things:
With any adhesive, you can prepare the surface either by roughing it up with some sandpaper
and then cleaning and degreasing it well or by actually activating the surface with a
bath in 80°C caustic soda for a few minutes – but please be really careful when trying
that and follow the usual safety rules. After that, they recommend regular superglue,
polyurethane-based resins or – tape! If you’ve ever stuck a GoPro to anything,
you’ll know how well that VXB tape sticks to stuff, so the chances are good that it’ll
actually stick well enough even to PETG parts straight from your printer. But in the same spirit, PETG is a much more
“friendly” plastic than some others. It doesn’t smell when printing and many
filaments are actually food-safe if printed right, it’s resistant against many chemical
including, surprise, glycol, the hard-tubing for PC watercooling, where glycol is a common
water additive, is actually often made from PETG these days. Also, PETG and copolyesters themselves are
UV and weather resistant, so the parts are going to stay strong and usable outside, but
the color might fade after a while in the sun. Overall, it’s just nice to print and for
most use cases is still close enough to PLA where it’s no big hassle to print, but still
gives you parts that are actually stronger than ABS and come with almost the same temperature
resistance. And your good, base-level PETG isn’t even
much more expensive than PLA, but of course, you can get it in all sorts of specialized
properties and price ranges if you’re into that. Let me know what your experiences with this
relatively new material are! I know I like it a ton and it has basically
replaced ABS for me. On the topic of ABS, a few of you have commented
on the last video that I completely left out vapor smoothing for ABS. So, I actually rarely vapor-smooth a print
because it’s a bit too much of a hassle, but I’d be really interested to hear from
you all if that’s something you do to your prints. Regularly. Or if it’s just a “eh, maybe twice a year”
kinda thing. If you liked the video, let YouTube know that
you do by giving it a thumbs up or subscribing! You can directly support the channel through
Patreon or by buying things through the affiliate links. Thanks for watching and I’ll see you in
the next one!

68 thoughts on “Things you should know about PETG

  1. Hi! Abouut video colors. Saturated image looks good but try to desaturate oranges to make skinn color more natural 🙂 THX for video 🙂

  2. AmazonBasics PETG is now my FAVORITE filament! For hi temp motorcycle parts I will still use Proto-Pasta HTPLA Carbon fiber, but the Amazon PETG prints awesome. Amazon may own the World soon….Oh yeah, I use Kapton Tape and purple glue stick on my Me Creator 1 printer and, well, it takes a couple minutes to remove the part from the bed.

  3. Some additional info helpful for beginners:
    – Clean nozzle is especially important for PETG.
    – Fan speeds are based on a Prusa. It needs to be tuned depending on the cooling setup you have. (On a Wanhao stock cooler, it's not very powerful and will have trouble bridging.)

  4. Gluing tip: Older video but the info might still be useful, I also been moving away from ABS to PetG, With my gluing experiments, i have found that the cleanest and effective method is to use Dichloromethane AKA acrylic adhesive. its the water thin glue you can apply with a squeeze bottle with a needle point tip, It give great control to where glue will be applied , instant bond properties and after a few minutes parts will rip apart before glue fails.

  5. I don't know how you do it, but I have tried to use Petg on about a dozen occasions now and every print was a bin job. Yet the exact same prints on the same printer with PLA come out perfect….. unfortunately PLA is rubbish and breaks down over time. Not sure what I am doing wrong but I get everything from lack of surface adhesion to the printing platform (even through I have it pre-heated to 90 C), SEVERE stringing, and lack of layer adhesion (you can literally pull a finished print about into individual print layers!) even though I am printing at 235 C. I purchased a fairly cheap roll of black Petg….. is there such a thing as garbage Petg? I would have assumed all Petg products would be to at least a basic standard of usability, so I am doubtful this is my problem.

  6. Thanks for the great video! I just started printing with PETG. I'm running on a MTW Create, glass bed. My biggest issues have been corner warping/edges pulling up as the print progresses. It usually doesn't happen until several hours into the print. I have mitigate it for the most part by Gorilla Taping the corners of my raft early on, but of course that doesn't seem ideal. I have been running the nozzle at 251 Celsius and my bed at 75 Celsius and no cooling fans. I am kind of stuck in not wanting to run things cooler but that may be the problem huh? Also my Printer isn't fully enclosed. I live in Wisconsin, so the cold weather has the humidity pretty low. My humidity in the area of my print bed is about 10% while printing…

  7. I bought a roll of PETG from hobby king, its clear PETG and I haven't had any luck with it, it oozes, strings, has poor layer adhesion, looks terrible and breaks really easily, it seems like the opposite of everything you described in your video. Maybe i just got a dud or something? I can't seem to dial it in, I have great luck with almost all the PLA and ABS i've used and I have printed a bunch of stuff in ninjaflex with great results too, but this one roll of clear PETG from hobbyking seems like it belongs in the garbage!

  8. "Solvent welding has some nasty chemicals involved so I don't really recommend it… but hey if you prep your surface with a hot lye solution you can use superglue!" 😂

  9. Most "hard to glue" plastics can be glued without problem if you just shortly before glueing activate them with acetone. Apply acetone and glue, works even for HMPE and should also work wel with PET-G.

  10. i use local extrudr Petg, good experience with black and transparent. tricky MF- metallic. nice vid Tom

  11. Hi Tom I have just watched your Things you should know about PETG printing and was interested in your do not print on glass warning I was about to print with PETG for the first tme and I print on a glass bed, well that is to say I print on a ultrabase type bed that has some sort of treatment to the surface I guess to emulate the texture of painter (masking)tape and I dom't have any trouble with adhesion at all well not the sort you showed us the recommended bed temp for the Hobby King supplied PETG is 35-60 deg C I am finding that anything under 70 deg C and the object being printed warps at 70 all good and when left to cool after printing it just comes off with little or no effort ???

  12. Man, I can NOT get my Petg that smooth. I get a very gritty finish to it most times. I really need to find a good slicer setting

  13. I really like petg even though I find I have spent a lot of time figuring it out. Videos like this are a big help. I'll try the no z hop from the comments because I've noticed that changes in z hop have had an effect. I've already got my travel speed up as high as my main printer can reliably run and that helped a lot. I do get some lifting at the corners sometimes and have had a hard time getting support / first layer interfaces dialed in for good part surface quality. On the other hand, I have printed 5" parts to within 0.1mm of accuracy using an uncalibrated printer and once calibrated properly got it down to 0.02 or 0.03mm of tolerance on parts. I find petg to be great stuff even if it is a little less forgiving than pla. All of this without a dedicated part cooling fan. In my next printer (a Creality CR-10S Pro that I'm upgrading right off the bat) I have even higher hopes.

  14. About PETG adhesion on glass.
    Use only heated glass surface and after printing when it cools down, it comes off itself without any need of external help.

  15. problem with glass fused to model? I print mainly PETG and mainly on pure glass. Ive had that problem twice only – when i did not wait untill the model to cool down. after the print is finished i recommend to put the glass with model sticked on it on cool floor. give the model 5-10 minutes and you will hear when it pops out.

  16. You swallow so many words mostly at the end of your sentence its very hard to hear what u are saying….

  17. Thomas, I've been enjoying printing with PETG on my Mk3s but ran into a problem with what to do with jammed up brass nozzles. I didn't want to throw them away because I've had problems with the cheap knock-off nozzles and the original E3D V6 nozzles are $9 each on Amazon. PETG was resistant to almost every solvent I tried–acetone, toluene, etc I could find. Some people use a blowtorch on them but it seemed a bit extreme. The solution I finally found was simple and effective–sulfuric battery acid, available at any auto parts store. Leave the nozzles overnight in a few centimeters of the battery acid. The next day, the plastic has turned to putty and is easy to poke out with a needle. The brass is totally unaffected. Hope this helps somebody and saves some money.

  18. a quick question is it true ABS and PETG are toxic we have to print in well ventilated area ? not like PLA

  19. This is really helpful, I was about to buy a PETG spool but didn’t know about the whole don’t print on glass thing. What’s nice is that my second option actually comes with a removable print surface and now I know why

  20. You should have a video where u actually print petg on prusa where u show what the issues actually look like.

  21. I don't know why I didn't notice this before, I was probably only listening at the time but IT'S OVER 9000!!!! 3:11

  22. thank you so much for making this video. I took your advice to modify settings- and after making PETG spaghetti for serveral prints before your video… Now my prints are pristine after watching your video!

  23. Hi, this is Echo from Hello3D, a manufacturer for 3D Printer Filaments for years. Now we just sell on Amazon US market, could you help to show our filaments on YouTube, please? We can send you free filaments to test and talk about the cooperation, thanks.

  24. I have had limited success printing small parts with petg but, when i try to print anything of size i have a blobbing issue that i have yet to master in marlin . This stuff loves to glob up on my nozzle and if left to continue will grow until it covers my heater block. This blob does an excellent job of destroying the build structure of my model. Any suggestions?

  25. I cant get petg to stick on the first layer, nozzle distance to bed is perfect, bedtemp is fine, bed is cleaned and dust free.
    while extruding it catches on the nozzle, gets dragged along and looks aweful, any suggestions?

  26. the only downside of PETG I have is it´s glassy and a bit transparent look … ABS looks much better "matt" 🙂

  27. making printer move as fast as it can handle sounds like a recipe to wear it out faster or break something…….. NO THANK YOU… I'll stick with PLA 🙂

  28. PETG is my absolute favorite. Straight up beast of a material!

    I've used it ever since I bought my first role of PETG–which was my second roll of filament ever.

  29. Also, the glycol (G) in PET-G makes it a hydrophobic material; essentially making water repel off of its surface without becoming absorbed.

  30. I'm getting started with it after getting familiar with PLA. I like how my usual PLA profiles (60/200) do work on this material but the fact it refuses outright to stick to my print bed (aluminium) is kind of annoying. To be fair I was expecting this as some of my PLA filaments also don't stick none too well to it.

  31. Okay i am making adjustments to try to print PETG as good as i can print PLA…it has been a challenge… using 4 tower test model i get zero issues… same setting with PETG had 4 fails… not stringing..just petg gets on nozzle than ends up breaking off tower… i printed at 240,245 and 250…same fails… i even slowed down print speed 40% ..still fail… On my ender 5 lcd screen my fan speed says 255…. not sure why…this 255 is for all my printing… in cura i set fan speed for 100%…confused about this… anyone understand what fan speed should say in tuning on printer monitor? I will also add 2 mm retraction and change the other settings he talks about here and test… thax

  32. I only print abs for the smoothing. If there is some thing els that prints easyer and more reliable and still good for vapour smoothing i would like to try.
    Almost all my prints get cast in metal. Most of them. So i dont need long life ore strength. In casting the factors that count is surface finish. Dimentional consistance. Surface finish. And burnout abillety ie not leaving ash… Little as posibal. Oooh did i mention surface finish.

  33. As someone who does a lot of finishing work after printing, how easy is PETG to sand? ABS sands a lot easier than PLA i've noticed, but is a pain to print as my printer is in my home office so I either have to move it or hook up the HEPA/charcoal filters. Trying to find a good alternative to ABS that's easier than PLA to sand and finish for prop making but still remains strong.

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