Under exrusion

[Horia]

Hello, we have some problems with our FFCP.
It seems like there is no consistent extrusion at the layer start or after travel moves.

Here are some pictures:
https://drive.google.com/file/d/0B_j...ew?usp=sharing
https://drive.google.com/file/d/0B_j...ew?usp=sharing
https://drive.google.com/file/d/0B_j...ew?usp=sharing

As you can see, there are some layers that start ok and some that don't.
Any ideas what could be causing this?

[curious aardvark]

it's a very small area - could have been an inconsistency in the filament maybe.

[Horia]

It is happening with every filament and almost every print.

[uncle_bob]

Hi

Are you trying to print a completely solid wall? It's not real clear what the print really is ....If you are, that is a very difficult task for a slicer / printer.

Bob

[Horia]

No, it's not the slicer. The problem is that after travel moves there is no extrusion for a few moments. Not all the prints have this problem, but when I print multiple objects on the same plate this happens.

[uncle_bob]

Hi

Let's back up a bit:

The slicer generates the gcode. The code is sent to the printer. The firmware executes the gcode.

If something is not happening then:

1) The gcode told it to do what it is doing.

2) The gcode did not get sent to the printer.

3) The firmware is not executing the gcode.

If the extruder motor is not moving when it should, then it's got to be one of the above. If the extruder *is* moving and noting is coming out, that's a bum extruder.

Bob

[Horia]

The cause is almost sure mechanical. We will probably need to change some parts in the near future. We made a detour and set the layer start points at random points to minimize the effect. In the photos the start point is at the same point each layer.

[uncle_bob]

Hi

Ok, so:

What kind of printer is it?

What kind of extruder is it?

What hot end is it?

What filament are you using?

What temperatures are you running?

What extrusion speeds are you set to?

Is the extruder motor moving or not?

If not:

What kind of stepper drivers are you running ? ......

Lots of possibilities and very little information to go on.

Bob

[Horia]

I mentioned in the first post that it's a Flash Forge Creator Pro, 2015 model. It has printed almost 1000 meters and I guess that it needs some service.
I didn't write a lot of information because we tested all possible settings in Simplify3D. We also have custom PID and JKN values.
Was hoping that someone else with FFCP had printed something similar (hollow cylinder) with same point for layer change and was curious if this effect appeared.

[uncle_bob]

Hi

Since you already have the problem solved ( = you know you have a broken extruder and need to strip it down), it might have been useful to present that fact earlier.

Bob