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

[Jester, Jr.]

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