Core-1 under extruded if Core-2 is used in the same layer

[JD-Art 1]

From the statement that "not all cores are created equal '' I have made a swap of the AA. At this point I don't remember if I haven't already tried that, but okay here goes.

 

Surprise no changes!

 

 

I found a way to exclude the z-axis as the problem, I think.

 

If I only use "1" wall the alternating lines shows both in flow and speed analyses.

 

 

And if there's more it disappears "from Cura but is still on the prints, kinda"

 

When printing the towers, it starts from the right and gowes to the left no. 6, 5, 4, 3, 2 when looking at the towers the first one prints fine (t6) and the last has the layer alteration (t2, t1 is the Pva one) (since the defect waries in the same layer it can't be a z-axle problem. right?)

 

So the problem starts at the end of a layer cycle. That's properly why the prime tower doesn't help, and setting a layer time of 20sek made it worse!

 

 

 

 

[gr5 2,167]

Could you please provide the gcode for this 6 tower print so I can understand the order of things better?

 

You are saying it prints the right most tower first?

 

And the problem gets worse over time and then after printing the PVA it gets better again?

 

Doesn't that imply something to do with the fan?  I assume he fan is at 50% for the left most tower.  For the pva.  I'd like to see the gcode though.

 

- George

 

 

[JD-Art 1]

I don't know why I consistently forget to attach the code.

 

UMS5_6T.gcode

 

Why do the analyser move the PLA towers position (t1) ??

 

When looking at the gcode analyser, the last PLA tower (t2) is printed with 50% fan speed.

But I'm not sure the fan is the problem. Because again if this was the case. Then it should only be (t2) that was affected and not gradually get worse from the first (t6) to the last (t2) . I would say that t3 is almost as bad. and that is printed at 100% fan.

 

 

 

[gr5 2,167]

It does indeed do walls at T6 T5 T4 T3 T2 then it moves the bed down a little and goes back to T6 T5 T4 T3 T2 then it does two layers on with the other core and finally the bed comes back up to repeat starting at T6 again.

 

If it was a Z play issue I would expect them all to be the same or T6 to be the worst (not T2).

 

Well T2 has the most assymetric cooling where every other layer it gets much more cooling (cooling while printing T1 which takes longer to print).  The other towers have quite assymetric cooling but no actual fan blowing on them for such a long time as T1.  But you did an experiment where the two towers were far apart.  So I don't think it's the fan.

 

Maybe it's nozzle temperature?  Have you tried to go to the printer's web page and look at the temperature graph?

 

Make sure your printer is in "developer" mode.  It will then show it's IP address.  Put that address into a browser and you should be able to see the printer's web page.  There is a link there for temperature graph.

 

Enable only nozzle temp for both nozzles to keep the graph clean.  Show a few layers where it is doing the PVA.  I think it would be MUCH more informative if you did this with the 6 tower print you did above.

 

[gr5 2,167]

Just to clarify - higher temperatures means the filament is less viscous and it flows more easily with less pressure from the feeder.

 

When the nozzle is colder the nozzle pressure is much higher.  The feeder doesn't skip but it has a knurled wheel that makes pyramid-shaped holes in the filament and when the pressure is higher, these holes elongate.  In other words the filament is flowing at (for example) only 80% of requested amount when the pressure in the nozzle is much higher.

 

Hence underextrusion when the nozzle is cooler.

 

[JD-Art 1]

 

I'm not sure how to read the graphs! if its the correct one.

 

 

 

[gr5 2,167]

In the first graph we can see that the green temp oscillates a bit - that isn't great but that's the higher temp PVA which isn't the problem.  The 1st graph also shows the orange line which is the PLA temperature and that seems to get more and more stable.

 

Meanwhile in the 3rd graph - the flow - we can see that PLA is being printed for a while and then it is not (presumably the PVA is printing then).

 

I'm surprised to see that the inactive PLA left core is not told to cool down.  I guess cura knows that there just isn't time to cool down and reheat the PLA nozzle.

 

So if the first and 3rd graph are in the same time frame then that tells me the problem is not temperature.  The PLA temp is quite steady - a little oscillation at first but pretty soon it appears it is stable for many layers.

 

[JD-Art 1]

Ok. not sure what the conclusion is then. If it's not a mechanical problem (machine) nor a printcore or temperature problem.

Then we are back to Cura or firmware?

The oldest version of Cura i have is the 3.5 and that also does it, so dont know.

 

I can sent it in for a professional service, but not quit sure that will help much. (doesn't seem to be a mechanical problem) and if it is a dying printer its kinda wasted to throw more money at it.

 

[gr5 2,167]

I guess I'm giving up.  I really don't understand it.  And this is easy and fun for me (figuring out puzzles).  You're the one doing all the work.  But right now I don't have any theories.  Maybe I'll think about it again later.