Top surface with PETg

[zappa79]

Hi everyone,
I have this problem when I print with PETg that my top surface looks blobby (please see picture.)

My infill settings are:
Internal fill pattern: Grid
External fill pattern: Rectilinear
Interior fill percentage: 50%

And I have 5 solid top layers.

Please help me, not sure what else to do?

[JSField]

Could be pillowing. Air in the pockets in the grid is expanding. Might need to print slower, maybe use a little bit of cooling fan. Try a lower infill %, the less plastic you have, the less heat you will have.

[zappa79]

Could be pillowing. Air in the pockets in the grid is expanding. Might need to print slower, maybe use a little bit of cooling fan. Try a lower infill %, the less plastic you have, the less heat you will have.

I am printing this at 35mm/s So not sure if slower would do any good?
I was reading somewhere that PETg needs at least 30-40% infill for a smooth surface, thats why I tries 50%, but you may be right, I will try 35% and see what happens, although I would like to be able to print stronger parts.

[zappa79]

Could be pillowing. Air in the pockets in the grid is expanding. Might need to print slower, maybe use a little bit of cooling fan. Try a lower infill %, the less plastic you have, the less heat you will have.

I just tried with fan on 30% and I got this mess...

[zappa79]

Could be pillowing. Air in the pockets in the grid is expanding. Might need to print slower, maybe use a little bit of cooling fan. Try a lower infill %, the less plastic you have, the less heat you will have.

Okay, since I don't seem to be able to use cooling fan, I disabled it again and tried to lower the infill down to 35%, you can see the result bellow.

It is even worse now, since it has holes in it, I am still using 5 solid top layers.

Is there a possibility to use cooling fan on just the top layers? To see if that will make any difference.

[dkightley]

Is there a possibility to use cooling fan on just the top layers?

You have full control over the cooling fan using the controls on the Cooling tab of the process.

Work out the layer number from the preview and enter a new line in the Fan Control table.

[zappa79]

Is there a possibility to use cooling fan on just the top layers?

You have full control over the cooling fan using the controls on the Cooling tab of the process.

Work out the layer number from the preview and enter a new line in the Fan Control table.

Could you please tell me exactly how to do that? Been looking in the preview but I dont see any numbers?
If I hit play it doesnt show anything counting, it just shows an animation, but I cant count the layers from there, it goes too fast for that.. I know I can slow it down, but that would take too long, so I am almost sure there is an easier way, but I am a complete newbie on simplify 3D.

[wirlybird]

It is pillowing and PETG is very prone to this. Increase the infill to at least 40% and add top layers.

[zappa79]

It is pillowing and PETG is very prone to this. Increase the infill to at least 40% and add top layers.

I started off with 50% infill and 5 top layers but it didnt help.. I only lowered the infill as per someones recommendation above.

Do you think cooling fan on the top layers will help? If not what are my options, increase the infill even more?
And more top layers?

[wirlybird]

Cooling fan is optional. With the fan you will get better looking surfaces but without you will get better bonding of the layers.

Go back to where you started and add some more layers. The infill type will also dictate how the layers respond. So 50% with 7-8 layers and see how it goes.

What are your temps and speeds?