Underextrusion in the upper right corner of the print

[jeroendewijs 0]

It is a often seen problem underextrusion. However, in this case most of the print is OK, but ust in the right upper corner, starting about half way the build plate, it starts to underextrude. Especially with a second print session on this printer. I already have set the flow to 150% in the first layer only, but it kept on happening that this corner was bad.

What is the difference of this area with respect to the other area? 

I came up with a simple trick.

 

The bowden tube is following the printhead in any direction. The curve of the tube differs with the position of the print head. 

But about half way the build plate, the bowden tube does not free follow the print head, it is a little blocked by the enclosure of the printer. This causes the tube to make a more stretched curve with the result that the filament flow is reduced a little by the space the filament gets inside the tube. This will cause underextrusion when the bowden tube hits the enclosure and the print head is moving away to the close right corner. 

 

What you want to achieve is a solid and steady filament flow controlled by the stepper motor of the printer, regardless the position of the printhead! 

The bowden tube is curving anyway but you want to have it the same in any circumstance. The blocking enclosure moment can be avoided to have the bowden tube ALWAYS fixed against the enclosure up to the top of the enclosure. So the bowden tube dus not start bending just above the stepper motor, no, it starts to bend just at the top of the printer enclosure. 

You can have it fixed with some kind of clamp, tape or whatever. It solved my problem,