Bubbling on top of projects?

[jeffmorris]

I have PowerSpec Ultra 3D (Flashforge Dreamer clone), Simplify3D, and PETG filament. There is bubbling on top of projects. The problem is worst on projects having large top surfaces. The extruder temperature is 240 degrees C. This forum doesn't allow me to insert screenshots. How can I fix the problem?

[IMG][/IMG]

[jeffmorris]

Please help me fix the problem.

[andysutils]

Hi Jeff.

I know its not the same filament I was using. But I had exactly the same issue. Please see my thread a few below yours and see if it helps

[djprinter]

It looks like the plastic is having a problem not spanning the gap in the infill.

There are three things to try:

1) lower temperature and/or added cooling
2) denser infill (so the gaps are smaller)
3) more top layers, to cover up the defects on the initial top layers

[jeffmorris]

I fixed the problem by lowering the extruder temperature, adding cooling, and using denser infill. Now, I have another problem: one nozzle got clogged and I couldn't clear it. I tried to use guitar string to clear the nozzle but I couldn't do it. I tried to force the filament through the extruder but I couldn't do it. I had to use the other extruder for now. A few months ago, I upgraded the original hot head to all-metal hot head. How can I fix the problem?

[jeffmorris]

I thought that I fixed the problem but this happened as shown in this image:



Is it possible to fix this using 3D printing pen instead of printing the whole thing again?

[uncle_bob]

The first thing to do is to stop printing important stuff and figure out what the problem is:

1) Have you switched filament? (it could be the material)

2) Have you cleaned out the hot end? (it could be full of crud)

3) Have you checked *all* the connections on the hot end? (is the thermistor loose?)

4) Have you checked the assembly of the hot end and extruder? (Is something loose / slipping / wobbling?)

5) Have you tried drying out the filament in a (warm not hot) oven?

6) Have you printed this filament successfully with this setup before? (Will it handle the material?)

7) Does a test print of a cube come out ok?

After checking all that, watch what the machine is doing. It probably is messing up at some point and then the problem is compounding as the print goes on. It's a lot easier to figure out what it wrong right a the start than all the way at the end. That is part of why test prints of simple objects help in diagnosing problems. They have very few features. When something goes wrong it's easy to spot ....

[curious aardvark]

but this happened as shown in this image:

Yeah, it really isn't shown in the image, that's so blurry it looks like a meringue as seen through 8 layers of net curtain, while squinting.

To take in focus close up pics. Stand further away, so that the camera can actually focus. and then crop the image down to the bit you actually want. Modern cameras take images with such a high pixel density that you'll generally get a much clearer, sharper and more detailed picture like that, than by having the camera too close to the object like you've done.

[ralphzoontjens]

It may be inherent to the filament so it is worth creating a small test geometry and printing it with every new filament you own before committing to serious work.
Otherwise try printing at an even lower temperature, and adding more cooling. With Cura, you can set the fan intensity based on height. Sometimes I add an external fan for critical areas.

Nozzle cleaning methods:
1. The Atomic method https://ultimaker.com/en/resources/1...-atomic-method
2. 0.3mm micro drill bits http://www.gearbest.com/3d-printer-parts/pp_273988.html
3. If that fails soak the nozzle for a few hours in MEK harder for PLA or Acetone for ABS.

[curious aardvark]

I would strongly recommend against drill bits for nozzle cleaning.
They are just too fragile and will inevitably snap in the nozzle. Yes I speak from experience :-)

Go for something flexible like a guitar string or piano wire.