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  1. #1

    PETG Tips from What I've learned over the last few weeks.

    Ok so i'm a machinist and I build stuff and I just got into 3D printing about a month ago. Crap!! Addicted, already bought the new MK3 Prusa, CR-10S and a smoking deal on a new Monorpice Maker Select Plus. The Cr-10s has been here about 2 1/2 weeks and literally has been running 24/7 for actual functional parts. The Maker Select just arrived and the Prusa is of course on order and is due to ship in the next few days.

    Since I'm making a lot of functional parts I needed strong material. I tried ABS, hated it. Returned the spool when I couldn't get it going right. I didn't want to mess with it as it was so temperamental. All the stuff I've read say PLA is great, but not good for heat and the like. Then I found some posts where people have been using it on machinery for years and no problem. So I started with that; as you should cause it's dam easy to print. I'm actually using PLA Plus+ from Monoprice and after trying some other popular brands I think it's a really, really good filament. I just wish the PLA Plus came in bigger spools. Only Black and White are 2Kg. The White PLA Plus from Monoprice is worthless. I couldn't get it to print anything good. I didn't try hard other than adjusting temp and that didn't do it.

    I got PETG early on and couldn't get it work correctly, from a mechanical point of view. I used some cheap filament in the beginning and it was pure junk. Once I got a spool of Hatchbox I could make great looking prints right off the bat, but they weren't strong like you would see in videos. In videos you see people wrenching on a part and it won't fail. Mine were breaking along the layer lines. As I said I didn't have the problems other people do like stringing and so forth, just no layer bonding.

    So I contacted Hatchbox and they tried to help, but to no avail. I mean they're still working on it, but I think I got it figured out.

    First off Simplify3D didn't work well for me. I find their settings to be a bit convoluted. And one of the parts I was making with a overhang, the supports never worked out correctly. The part on top of the support would warp. I like Cura a lot, but you have to know how to use it properly as I just learned.

    So with Cura when you first start you'll start to notice what settings change and which do not. You need to expand the settings to show everything then you can start hiding ones that are not of any concern, which is most. My problem was I was changing fan settings and get no different results, because the setting I changed didn't affect all of the fan settings. SO expand all the settings so you can see what changes.

    I'm using a CR-10S. PTEG, I'm sure, sticks better to other things, but this is what I'm using and it works, for now. I'm using the glass that came with the printer. You have to use some sort of sticky stuff. I'm using washable white glue stick from Elmers. I originally was using the Purple washable glue stick that turns clear when dry, but ran out. The purple stuff sticks a little better than the non-purple washable glue stick. The non-purple is easier to apply; smoother. The purple is a little more gloopy.

    Here's the most important thing aside from Cura Settings. KEEP THE NOZZLE CLEAN on the outside. All my prints that failed were ones I didn't pay attention to the first layer. Always use a skirt to clear the nozzle. Then you HAVE to watch the nozzle and physically clear the outside with your putty knife as it's laying down the skirt. This is the most important thing. If you get build up on the outside of the nozzle your print will fail or look terrible.

    I'm using a stock CR-10S mind you. SO the following may not be an issue for people with upgraded nozzles and/or extruders.

    So once you get that first layer cleanly laid down with no build up the setting make a difference.

    I didn't adjust my bed lower for PETG as some people say. I use .3 Layer height for the first layer then .2 After that. Here's the rest of my settings and how the print came out. If you don't see a setting listed then it's stock from Cura > PETG > Draft Setting.

    .2 Layer Height
    .3 Initial Layer Height
    1.2 Wall Thickness
    Lines - Top/Bottom Pattern
    30% Infill
    Temp 242-250C See below for test pieces.
    80C Bed Temp
    6.2 Retraction
    Speed 15-25mm/s See below for test pieces.
    Travel Speeds 100
    Print Cooling Depends See Below
    4 Lines of Skirt

    I printed a test piece I found on Thingiverse, it's a small round thing. See pic.

    Here's the samples I printed from experimenting earlier.

    242C, 15mm/s for all speeds, 20% Fan - Great Looking Print Strong, not super strong. Kind of breaks at the weakest point, kind of along layer lines.
    242C, 15mm/s for all speeds, 10% Fan - Great Looking Print- VERY Strong doesn't break along layer lines. Clearly strong.
    242C, 15mm/s for all speeds, No Fan - Great Looking Print- VERY Strong doesn't break along layer lines. Clearly strong.

    Then I went to a little higher speed as 15mm/s is painfully slow especially when moving onto bigger parts.
    250C, 30mm/s for all speeds, 20% Fan I printed this twice. Couple of missing small areas. I'm assuming from not being able to extrude fast enough. One came out missing the small areas and one came out great. Very strong.
    250C, 30mm/s for all speeds, 40% Fan Oddly enough came out very strong and great looking. I say oddly as the last one below was weak as can be.
    250C, 30mm/s for all speeds, 40% Fan less retraction as I read one post where they didn't use as much retraction. Looks alright, but weak.

    I think the extruder couldn't keep up all the time or I needed higher temp, but with a stock machine I'm not going higher than 250C so the last one I'm printing right now that's 250C, 25mm/s and No Fan.

    Funny cause lots of people say when you use no fan you lose quality. If the print didn't skip in places all the tests I tried came out looking great. Now this was for a small part. Print time from 20-55 minutes.

    So I'm going to test the original part I was trying to make and see how strong that gets and if it looks alright.

    Oh, one last thing for my stock fan to work at 10% I had to let it finish it's first layer then when the fan was supposed to turn on it didn't until I spun it by hand to get it going.Test Piece.JPG
    Last edited by Jester, Jr.; 04-21-2018 at 05:56 PM.

  2. #2
    Follow up. I just finished the last test. 250C 25mm/s No Fan. Prints great and strong, but not nearly as strong as the slower less hot ones. I think I'll go with 242C 15mm/s No Fan. Here a pic of the finished part and break line. It's not breaking at the layer line.
    IMG_0907.jpgIMG_0908.jpg

  3. #3
    Further follow up. Just tried printing some small parts for a belt tensioner for my Maker Select Plus, https://www.thingiverse.com/thing:1784375, took 3 tries to get the small parts to stick to the bed. So I redid it with a brim instead of skirt. Still had trouble in one area. So I guess I'll move to a more PETG sticky friendly surface.

  4. #4
    have a look at printbite - works great for pet-g.

    If filament is building up on the outside of your nozzle, then there's something wrong. It shouldn't.

    And as far as pla goes - don't listen to the vast majority of the interweb. They're still stuck 5 years ago.
    Modern filaments are way better.
    Also a lot more choice now than there used to be.
    The newer filaments are pretty pricey, but a couple I can definitely recommend are ninjateks armadillo - a rigid polyurethane.
    Innofill's pro 1.
    And taulman nylon 645. That's the only one that doesn't like printbite. But it prints incredibly well for a nylon. Probably the best to print with I#ve yet tried.

    Also have a look at: https://globalfsd.com/
    Great source for trying out different types of filament.

    One thing to bear in mind. The settings you have work for you, in your workshop with your specific printer.
    They probably won't work for me.
    Also have alook at deltas. I3's are fine (I think that's all you have). But very slow and a lot of movement and vibration that effects a lot of printing aspects.

    Pet-g is interesting stuff and it does depend a lot of make. At the end of the day you need to print it slow and not that hot.
    For most things I still find pla superior.
    That said, If I could afford it I'd probably switch to pro 1 or armadillo for everyday prints. The armadillo
    in particular, is awesome stuff.

  5. #5
    Thanks very much for the suggestions. I'll check those out. I did buy some Taulman Tech-G as I know their filaments are supposed to be great.

    As for the setting I understand what will work for me might not work for someone else, but by posting the journey and how I got there and what I needed to pay attention to might help someone else.

    You said if I get build up on the outside of the nozzle then something is wrong. What do you mean exactly. Maybe I should explain further. I only get build up on the outside of the nozzle when it's trying to lay down it's first layer and is not successful. That filament has to go somewhere and for me it sticks to the nozzle in a ball.

  6. #6
    your nozzle is too close to the bed.
    There should always be sufficient room below the nozzle for the filament to extrude. Even if the filament is 'smooshed' it should all go on the bed.
    It sounds counter intuitive, but often you will get a much better layer by raising the nozzle slightly.

    And yep, first layer is the most important.

    So basically if the filament is being scraped up and sticking to the nozzle. Increase the nozzle gap and slow the first layer print speed down.

    It's not unknown for particularly problematical filaments for me to go down as low as 1 or 2 % set print speed for the first layer.
    Some prints the first layer can account for 50% of the overall print time. If the print is succesful - then who cares :-)

    The only filaments where this doesn't apply tend to be flexible ones. Those I pretty much always run the first layer at 100%. Basically they have zero warp and are much stickier. Usually my first layer speed is 5 or 10 % of set maximum print speed.

    Seems weird that anyone would prefer cura to simplify3d. But I guess we are all different.
    I find that all the crucial settings are logical and easy to use in s3d and almost impossible to find in current cura.
    The older versions of cura were much easier to use.

  7. #7
    lol - tried to print a pet-g clip last night to attach camera to shotgun barrel.
    Been a while but I don't remember it being such a bastard.
    can't seem to get it to stick to printbite for more than half the print and getting a lot of stringing. Which is weird as there's no point during the print where the print head leaves the model. no crossing or travel points. So how on earth is it creating so much string ???

    Unfortunately without splitting the model and adding a nut and bolt and going back to pla - pet-g is the best suited material for a simple clip.

    haven't gone up as high as 80c on the bed yet. I'll try that next.

    Just don't remember it being so temperamental :-)

  8. #8
    That's funny. I tried to make a print in PETG last night as well. SAME DAM thing couldn't get it to stick to the bed for the life of me. I tried 6 times with different height and speed settings. Couldn't get past the first layer. Nothing would stick. Tried hairspray, glue stick..nothing!!

  9. #9
    HI Guys,
    Just starting out with PETG from MG chemicals (White) and having some issues. I am wondering if moisture in filament is a huge problem.
    My sad story goes like this.
    Working with a large sized 2mm thick walled item.
    Prints in PLA good, but environmental concerns (Higher temperature application) forced me to try something else. Can't have the smell of ABS. So tried PETG. First item printed fine( lots of stringing) was printing at 228C. Vendors says 210-240C.
    Then could not get a print to go past raft and first couple of layers. Blobs and bumps.
    Finally gave up and tried to print with PLA.
    Nozzle was plugged but finally got it cleaned out and is happily printing PLA.

    So what changed between print?. Its an 18 hour print so the one thing was filament went from sealed package to room humidity.
    Its the wet season in BC so our humidity is high, 50-90 % the last few days.

    Suggestions welcome.
    Dave

  10. #10
    It's very well possible. You can dry filament out. Just put it in an oven for 2 hours at 120 Fahrenheit, not sure what Celsius is, but do the conversion and you'll be good.


    @ Curious, I just put down blue tape and wiped it down with alcohol and the PETG seems to be sticking. I knew this, but figures glue stick or hair spray should work as well, but I guess not. I'm also using a raft because the first layer of the part I'm making has some fine detail so I need the first layers to be good.

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