Under extrusion in odd place

[king-carl 0]

 

Ive had this problem a few times. Sometimes when printing the model look under extruded in odd places but looks good everywere else.

In the pictures above the boat is underextruder on the left side but not in the right. The same thing happens inside of the model too, so its not only edge related.

/Carl

 

[ian 32]

very very strange that your getting under extrusion on one side and not the other....

what speed and temp are you printing with ?

I have also had problems with under extrusion and the only combat iv found against it is.. to bring up the nozzle temp to 250... and lower the speed to 50... then the filament comes out warm and steady..

about the underexstruction.. i have to think about that one....

Ian

just.. thinking.. could it be that your print bed is not level ? and the nozzle is being pushed tighter aginst some sides than other.. then the flow would be different and might even help stop the flow or show up as underexstrusion on some sides ?

 

[Dim3nsioneer 557]

If you rotate the object by 180 degree, does the underextrusion then happen on the other side?

 

[king-carl 0]

Ive tried changing temp but it didnt make any difference. And I tried changing flow but that didnt make it better either.

I havent tried to rotate the object, but in other prints, with the same problem, it seems to end up at the same spot (almost like the filament gets pinched at a specific position).

 

[ian 32]

did you check your extruder and bowden that there is no loose pieces of pla blocking up the flow ?

sometimes thin strings of pla can get left in the bowden and extruder and can cause problems...

 

[Dim3nsioneer 557]

If the diameter of your filament is close to 3mm, I may check if there is more friction in the Bowden tube when the print head is at the 'underextrusion site'.

 

[Dim3nsioneer 557]

Sorry, I didn't see Ian's post when I wrote mine...

[gr5 2,173]

UM1 or UM2? The UM1 has fan only on left side and the nozzle on the UM2 is closer to the left fan. This causes assymetric cooling of the nozzle (you don't want *any* cooling of the nozzle of course) and can mess with the nozzle temperature for a few seconds causing underextrusion on one side. I would expect it worse as the nozzle is more to the right side because the flat surface of the part is under the fan bouncing the air across to the nozzle.

The PID adjusts within 30 seconds (which might be too slow) and then it overshoots in temp a bit.

The solution is to print 10C hotter. 240C is a safe printing temp. 250C is dangerous. Never leave the machine just sitting there with the temp at 250C or it will cook to a black gunky mess.

 

[king-carl 0]

Its an UM1.

The settings that Ive found usually works for me with PLA has been 210C, but when this happened I tried changing to 230C, but it didnt work. It is possible that its the fan, but the problem area wasnt on the right or left side, but rather towards the back/middle of the model.

I have a suspicion that it could have something to do with the nozzle, Ill get new ones tomorrow, so Ill try that. And also Ive heard that sewing machine oil in the filament tube could help.