PET settings?

I've just taken delivery of some clear PET filament, and I haven't quite worked out the settings yet.

Here's what I've done so far:

Nozzle temp 225C, heatbed temp 60C, print cooling fan, no brim - results not too bad, but the test cube was starting to curl on the corners and hardly stuck on the glass.
Nozzle temp 230C, heatbed temp 100C, no print cooling fan, brim - gave up part-way through as it was clear that the deposited plastic wasn't solidifying and was picking up as the nozzle went over. Print was very soft when I cleaned up the glass.
Nozzle temp 230C heatbed temp 60C, print cooling fan, brim - Initially not too bad, but also started to pick up.

Now most people know the starting points for PLA and ABS, but I don't have the same for PET; the suppliers only gave the recommended hotend setting of 210C - 230C. They also used the terms PET and PETG randomly in their advert, so I'm not entirely sure what I've got (an email has been sent, but no reply yet).

So - for the time being - can anyone give me some basic parameters? For example:

• Hot-end temps
• Bed temps
• brim or no brim
• print cooling fan, or not

Thanks,
David

I have only done a little printing with PETG, but 70C bed and 225C hot end has worked for me so far. The bed surface is PEI. Using clear PETG from Rigidink.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Those are the sort of settings I was working towards... do you use the print cooling fan, and/or a brim?

I use a bed temperature of 70 and a nozzle temperature of 235 to 245 depending on the filament. I am using eSun PET-G. Not show how much difference in print settings there are between PET and PET-G. The other thing I read when starting with PET-G, is you need to slow down the printing speed.

I've been trying PETG too, but not doing too well. I get poor layer adhesion until I bring the temperature way up, and then struggle with the infill getting melty. I'm running 250/85 and using lots of cooling fan. Hex fill seems to work better than line. The current settings work fine for shapes without too much detail though, such as this lamp shade, printed at 30 mm/s.

Quote
JamesK
I've been trying PETG too, but not doing too well. I get poor layer adhesion until I bring the temperature way up, and then struggle with the infill getting melty. I'm running 250/85 and using lots of cooling fan. Hex fill seems to work better than line. The current settings work fine for shapes without too much detail though, such as this lamp shade, printed at 30 mm/s.

What brand filament are you using? Is it a name brand or the cheapest stuff you find on eBay?

Here is a print I have running right now using eSun Red PET-G. Nozzle is at 245 (probably a bit hotter than it needs to be - lots of stringing), bed at 70. 45mm/s perimeters and 60mm/s infill.

It's filaments.ca house brand. All of their other filaments I've used have been great, so I suspect it's more likely user error than any issue with the filament quality. Yes, I get plenty of stringing too. I read one comment that suggested if PETG wasn't stringing it probably wasn't hot enough to give good layer bonding.

Well, I've taken up some of your suggestions, and the results are quite pleasing:



The cube on the left was the first one I made - temp 225C, bed 60C, printing at the speed I normally use on my CoreXY printer (quite fast). Its surface is quite ragged and rough to the touch, and the clarity of the plastic is poor. It's quite strong, but one corner was curling up by the end of the print.

The cube on the right I made just now: temp 225C, bed 70C, printing at half-speed, with slight print cooling fan (if I have the fan too high it knocks down the nozzle temp - the fans are too efficient!). Although it looks rough in the picture, the surface is very smooth - the stripes you can see are a result of the 33% infill showing through the perimeter.

So - decent progress, but more fiddling is required before I can be truly happy with the results. I'm not sure that PET will take over 100% from PLA and/or ABS in my printing, but I think it will have a place.

Thanks for all the input.

Looking good! Did the infill form cleanly? Here's an interesting test - if you print a hollow test cube with two perimeters, no top, no bottom, do the two perimeters bond together well? Even when I've got the vertical layers well bonded, I find that I can easily split apart the two perimeter layers with petg, but not with pla, abs or nylon.

Edited 1 time(s). Last edit at 01/08/2016 06:28AM by JamesK.

I just tried to print something else a bit larger, and infill was a problem - it seemed to miss small areas. I found that increasing the fan speed slightly allowed the extrusion to bridge any gaps and cover over the missed bits.

So far I've had to reduce the extrusion rate to 80%, slow the print speed right down, fiddle with the fan speed, and hover around the printer with tweezers to catch the occasional large string that would randomly appear. So - not as trouble-free as PLA or ABS!

I could also see people having extruder problems with PET - in 1.75mm it is quite soft and flexible, and the hobbed gear was cutting quite deeply into the filament. I was OK even though I have a bowden extruder, but maybe I was lucky.

Edited 1 time(s). Last edit at 01/08/2016 07:16AM by David J.

I noticed print quality with PETG getting a lot better with fans. If that is a problem for your hotend maybe cover it
[www.thingiverse.com]
[www.thingiverse.com]

---

[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

It's not a real problem - I designed some fans to go on my CoreXY printer - Thingiverse link - and they can be too effective!

All I've done is reduce the fan speed range in the slicer, and it seems to be working OK now.

I print PetG at 245 degrees with bed temp of 70. Retraction of 2 and no brim, Hair spray on blue tape with no warping. Speed at 30 with no stringing.
No fan either.

Edited 1 time(s). Last edit at 01/08/2016 12:52PM by Putzer.

Here's what works for me, and works wonderfully well. Quoting from the other thread.

Quote

Settings on my i3v Prusa 10" were very similar to ABS: J-head 0.5mm at 225 degrees, bed at 80 degrees (i.e. lower than ABS). Same print speeds: 30mm/s perimeter, 60mm/s infill. I used 3mm clear PETG filament from user "leox-life" on ebay.

The bed for above is clean, plain glass. Retraction 1, no brim, hotend fan on full speed.

Edited 2 time(s). Last edit at 01/10/2016 12:12PM by stamasd.

I usually print PetG at 245 with a 80degree Bed on PEI, I also use a 6mm Retraction (Direct)

Edited 1 time(s). Last edit at 01/11/2016 12:58PM by makerparts.

---

Makerparts.ca
Your Canadian source for V-Slot Extrusion, CNC and 3D Printing Parts and Accessories.
we are proud to be an official Openbuilds distributor.

Quote
makerparts
I usually print PetG at 245 with a 80degree Bed on PEI, I also use a 6mm Retraction (Direct)

That is a lot of retraction for a direct drive. What hotend are you using?

Using a E3D v6 (3mm) and a Bondtech V2 Extruder with PetG I need to go to 6mm to reduce stringing / oozing

---

Makerparts.ca
Your Canadian source for V-Slot Extrusion, CNC and 3D Printing Parts and Accessories.
we are proud to be an official Openbuilds distributor.

We @ www.3d-seed.com love the new Motedis PETG..!!

So much we're back printing our extruders (www.Bondtech.se) in it..!!

And it's 16 euros per kg including IVA..!!!

www.motedis.es

I print PETG with 245° nozzle and the bed at 100° thermistor setting (about 85° on the top of the glass.)
A print cooling fan is not needed. I get excellent adhesion on clean glass without any tape/glue.
I have used 3 brands of PETG:
[www.ecoreprap.com] supply PETG to order, any specified colour in 5kg quantity.
[reprapworld.com] REAL PETG
eSUN
I have had no problems with the first 2.
The eSun PETG gives poorer first layer adhesion whereas the first 2 are perfect. The eSun filament also gives slight stringing.
I found lower bed temperatures gave poor adhesion. At 100° it is perfect on glass. The print holds firmly to the glass until the bed cools.
Large prints adhere very strongly to the bed even after cooling but come off easily if I remove the glass from the printer and run cold water over it for 5 seconds.
I don't see any reason to use PLA or ABS again except to use up my stock.
Some suppliers seem confused about the difference between PET, PETG and PETT.
I tried PETT but had adhesion problems and it is very expensive.
I also tried some clear PET which has quite different characteristics and is closer to PLA than it is to PETG. A print cooling fan was needed to prevent warping.