PETG Part Warping/Bowing

[Kyle608 0]

I recently printed a fairly large part that took around 30 hours of print time. I've only printed this part once so I don't have too much data to give but I wanted to see if anyone had any tips before printing another part and getting the same result.  I printed the part using Ultimaker PETG material on an Ultimaker S7. The part overall looks good and seems to have printed well. Hole locations are pretty spot on aside from the holes being undersized about .015". However, the part seems to have warped along the Z axis during the print. As you can see in the pictures attached, the model and Cura do not reflect any sort of curvature in the Z direction, however the part does. I wanted to see if anyone has seen this before and has a possible solution. I was maybe going to print with ABS or PC next to see if that helps anything. 

 

I used the Normal Engineering 0.15mm print profile with 20% triangular infill. Printing temp was 240°C, build plate was 85°C, and cooling fan speed was at 20%. I did not use any support and I did not use Adaptive Layers.

 

Thanks in advance for the help!

[GregValiant 1,258]

It needs elephant ears on the build plate, up high you will need a windscreen or something.  (My bad...I just noticed it's an Ultimaker).

 

I print mostly PETG.  A couple of us here fooled around with some non-scientific testing.

 

This model is a shark fin for mounting on the roof of our car.  It's an "old folks" aid for parking lots.

 

You will note that it has large break-away elephant ears to try to hold it down to the bed.  You can see below that they were barely adequate.  It was pulling hard.  This was with hair spray as an adhesion promoter.

 

 

You also are getting warpage up high.  That one I haven't been plagued with.  If you get a draft from an air vent (when the air-condo or furnace cycle on) you can get something like that.  The fact that it is "directional" is a clue.  One side shrank faster than the other side did.

 

Here is the fancy shark fins for Sundays.  I have to take them off at the car wash.

Edited September 28, 2023 by GregValiant

[Kyle608 0]

Hey Greg, thanks for the quick response. I am running another part over the weekend. Changes I made:

 

• Added a draft shield
• Using a raft at 19mm offset instead of a brim (do not have an elephant ear option)
• Reduced print speed from 30 mm/s to 25mm/s
• Turned print cooling off

Will report back next week on the results from the print.

[GregValiant 1,258]

When printing materials that are prone to warping (PETG, ABS for example) the question that you often have to answer in regards to layer cooling is "how much" and "when".  Cura can turn the fan on, but then it leaves it on.  That isn't usually optimal.

So I wrote this post processor.  You can turn the fan on for certain features (or for certain layers) then turn it off again.  I find it comes in handy for cooling Support Interfaces, the first skin layer over Infill, feather edges that want to warp up and get hit by the nozzle, etc..

Unzip the file below and put it into your "Configuration" folder in the "scripts" sub-folder (use "Help | Show Configuration Folder" to locate it.)

The post will be available with the others under "Extensions | Post Process | Modify Gcode" and then "Add a script".

It's in line for consideration by the Cura team but it won't make it into 5.5.

(The "By Feature" option is better for large prints and the "By Layer" option is better for smaller prints.)

 

AddCoolingProfile.zip