<p>I got a roll of Hatchbox PETG and the prints are fantastic. Small test prints don't break along the layers even at higher fan speeds. The problem was the Polymax PETG. I took a look at the TDS for it and the impact strength on standing samples was only 29% of the standing ones. I believe the Polymax PETG just has inherent layer adhesion problems.</p>
<hr />
<p><em>Please note that Polymax PETG isn't PETG, it's PCTG. I may try doing some firmware changes and printing it at 270 °C later on.</em></p>

CC BY-SA 4.0
2021-07-07T05:27:20.677Z
2021-07-07T08:33:22.353Z
2021-07-07T08:33:22.353Z
TreeBarkEater
<p>I had this problem with my Ender 3 until I changed to a different extruder and now PETG never has adhesion problems. Even 100 % fan is fine at 245 °C. I think the stock hobbed gear just slips on PETG really badly, giving underextrusion. Go slow, increase the flow to compensate, and possibly increase temperature slightly more. Or buy a decent extruder.</p>

CC BY-SA 4.0
2021-06-12T04:31:52.193Z
Why would it under extrude if the esteps are calibrated?
TreeBarkEater
CC BY-SA 4.0
2021-06-12T04:57:21.140Z
@TreeBarkEater: Calibrated under what extrusion rate? Actually pushing material thru hotend at print speed, or just moving it in the bowden? My best understanding of what I experienced was that there was just a lot of slipping under backpressure, and this is really bad for PETG if you're using linear advance since it needs a fairly high spring constant that increases the pressure (and thereby slippage) even more. Also, if you're not using linear advance, that will give rather inconsistent extrusion that also makes the layers adhere poorly.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2021-06-12T04:58:40.890Z
One more thing: combing is bad for PETG. Because it's so sticky, moving over already-printed material without retracting tends to drag it, making a poor surface for the next layer to adhere to. Try turning combing off (or leaving it on but setting max comb distance without retract to < 1mm).
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2021-06-12T06:16:17.730Z
The OP is already printing pretty slow, the max recommend speed of the PETG I'm using (printed about 20 kg of 2.85 mm filament) is 55 mm/s, so I wouldn't call the OP's speed fast. I fully agree on using a decent extruder.
0scar
CC BY-SA 4.0
2021-06-12T13:29:30.963Z
@0scar: it's not fast, but maybe fast relative to Creality's extruder.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2021-06-12T16:40:03.773Z
I would think it is being over extruded because when I calibrate the e steps it's extruding faster than when printing.
TreeBarkEater
CC BY-SA 4.0
2021-06-12T17:19:20.180Z
@TreeBarkEater: I don't follow what you mean by that. If you mean you're doing the calibration with actual extrusion taking place (pushing material out the nozzle not just thru the bowden) that's good, but keep in mind that actual printing is performed by pressing the extruded material against a surface, not extruding into thin air. The backpressure is completely different.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2021-06-12T17:23:25.230Z
To test this with any certainty, you need to either mark the whole intended extrusion length for a print on the filament, and see that it matches after printing a nontrivial size print, or weigh a print with scale that's sufficiently precise an compare to the theoretical extruded mass.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2021-06-12T04:20:42.150Z
2021-06-12T06:09:54.870Z
2021-06-12T06:09:54.870Z
R.. GitHub STOP HELPING ICE
<p>The layer adhesion with Polymax PETG at 260 °C was great so I didn't go any higher.</p>

CC BY-SA 4.0
2021-07-17T01:02:05.170Z
2021-07-17T02:41:30.163Z
2021-07-17T02:41:30.163Z
TreeBarkEater
<p>I have recently started printing with Polymaker's PolyMax PETG on my Ender 3 v2. I have not been able to get the layer adhesion anywhere near as strong as it should be. I would guess it is around 20-25 % of the strength in the XY direction. The parts snap easily along the layer lines under loads that PLA and nylon hold up to just fine.</p>
<p>Print settings:</p>
<ul>
<li>0.15 mm layers @ 35-20 mm/s</li>
<li>Hotend temp 245 °C</li>
<li>4 mm retraction @ 40 mm/s</li>
<li>combing on</li>
<li>jerk control on</li>
<li>no cooling</li>
</ul>
<p>I made sure to use a nickel-plated brass 0.4 mm nozzle. I have calibrated my E-steps and tried printing in an enclosure, but nothing seems to help with layer adhesion. I have made sure there is no debris getting on the filament as it comes out of the drybox and even tried taping around the heater block so there is absolutely no part cooling.</p>
<p>Any ideas as to what I could be doing wrong?</p>

CC BY-SA 4.0
2021-06-12T06:19:09.017Z
Have you already tried a thicker layer height to see if that makes a difference?  E.g. 0.2 mm?
0scar
CC BY-SA 4.0
2021-06-12T16:41:33.290Z
Yes, and it makes no difference. A wider line width just leaves lots of blobs on the print. I think it is over extruding slightly.
TreeBarkEater
CC BY-SA 4.0
2021-06-12T22:49:11.343Z
Maybe you misinterpreted the comment, I wasn't talking about line width; I commented on layer height. PETG prints better when layer height is not too small, I've mainly used 0.2 mm and printed kilometers of 2.85 mm without major  problems.
0scar
<creality-ender-3><adhesion><petg><print-strength>
PETG layer adhesion problems
TreeBarkEater
# PETG layer adhesion problems

(Asked by: username_0 on 2021-06-11)

I have recently started printing with Polymaker's PolyMax PETG on my Ender 3 v2. I have not been able to get the layer adhesion anywhere near as strong as it should be. I would guess it is around 20-25 % of the strength in the XY direction. The parts snap easily along the layer lines under loads that PLA and nylon hold up to just fine.

Print settings:

* 0.15 mm layers @ 35-20 mm/s
* Hotend temp 245 °C
* 4 mm retraction @ 40 mm/s
* combing on
* jerk control on
* no cooling

I made sure to use a nickel-plated brass 0.4 mm nozzle. I have calibrated my E-steps and tried printing in an enclosure, but nothing seems to help with layer adhesion. I have made sure there is no debris getting on the filament as it comes out of the drybox and even tried taping around the heater block so there is absolutely no part cooling.

Any ideas as to what I could be doing wrong?

**Tags:** creality-ender-3, adhesion, petg, print-strength

> **Comments:**
> **username_1**: Have you already tried a thicker layer height to see if that makes a difference?  E.g. 0.2 mm?  
> **username_0**: Yes, and it makes no difference. A wider line width just leaves lots of blobs on the print. I think it is over extruding slightly.  
> **username_1**: Maybe you misinterpreted the comment, I wasn't talking about line width; I commented on layer height. PETG prints better when layer height is not too small, I've mainly used 0.2 mm and printed kilometers of 2.85 mm without major  problems.  

---

## 3 answers

### Answer by username_0 on 2021-07-07. Score: 1 | Accepted answer

I got a roll of Hatchbox PETG and the prints are fantastic. Small test prints don't break along the layers even at higher fan speeds. The problem was the Polymax PETG. I took a look at the TDS for it and the impact strength on standing samples was only 29% of the standing ones. I believe the Polymax PETG just has inherent layer adhesion problems.

---

*Please note that Polymax PETG isn't PETG, it's PCTG. I may try doing some firmware changes and printing it at 270 °C later on.*


---

### Answer by username_2 on 2021-06-12. Score: 2

I had this problem with my Ender 3 until I changed to a different extruder and now PETG never has adhesion problems. Even 100 % fan is fine at 245 °C. I think the stock hobbed gear just slips on PETG really badly, giving underextrusion. Go slow, increase the flow to compensate, and possibly increase temperature slightly more. Or buy a decent extruder.

> **Comments:**
> **username_0**: Why would it under extrude if the esteps are calibrated?  
> **username_2**: @username_0: Calibrated under what extrusion rate? Actually pushing material thru hotend at print speed, or just moving it in the bowden? My best understanding of what I experienced was that there was just a lot of slipping under backpressure, and this is really bad for PETG if you're using linear advance since it needs a fairly high spring constant that increases the pressure (and thereby slippage) even more. Also, if you're not using linear advance, that will give rather inconsistent extrusion that also makes the layers adhere poorly.  
> **username_2**: One more thing: combing is bad for PETG. Because it's so sticky, moving over already-printed material without retracting tends to drag it, making a poor surface for the next layer to adhere to. Try turning combing off (or leaving it on but setting max comb distance without retract to < 1mm).  
> **username_1**: The OP is already printing pretty slow, the max recommend speed of the PETG I'm using (printed about 20 kg of 2.85 mm filament) is 55 mm/s, so I wouldn't call the OP's speed fast. I fully agree on using a decent extruder.  
> **username_2**: @username_1: it's not fast, but maybe fast relative to Creality's extruder.  
> **username_0**: I would think it is being over extruded because when I calibrate the e steps it's extruding faster than when printing.  
> **username_2**: @username_0: I don't follow what you mean by that. If you mean you're doing the calibration with actual extrusion taking place (pushing material out the nozzle not just thru the bowden) that's good, but keep in mind that actual printing is performed by pressing the extruded material against a surface, not extruding into thin air. The backpressure is completely different.  
> **username_2**: To test this with any certainty, you need to either mark the whole intended extrusion length for a print on the filament, and see that it matches after printing a nontrivial size print, or weigh a print with scale that's sufficiently precise an compare to the theoretical extruded mass.  

---

### Answer by username_0 on 2021-07-17. Score: 0

The layer adhesion with Polymax PETG at 260 °C was great so I didn't go any higher.


---

