Over extrusion and under extrusion at the same time?

[th3o 0]

I have a problem with my UM2.

Looks like I have over extrusion and under extrusion at the same time.

At 200C there are layers with under extrusion and at the same time there are blobs like there is over extrusion.

Increasing the temperature makes the under extrusion layers disappear, but leaves me with the blobs.

Decreasing the temperature makes the blobs disappear, but leaves me with underextruded layers.

On the picture (printed at 210C) you can see the blobs, and in one of the middle layers you can already see some under extrusion.

I do have a picture of one printed at 200C but I have trouble uploading it.

On that one you can see heavy under extrusion and blobs at the same time.

Printing at (much) slower speeds makes no difference.

Bed temperature (50C) makes no difference.

Changing filament (Ultimaker or Colorfabb) makes no difference.

What can I do to solve this?

 

[gr5 2,189]

What print speeds are we talking about? You mentioned printing at "much slower" speeds. What was the faster speed and slower speed or what were all the speeds?

 

[th3o 0]

Fast = 100 mm/s

Slow = 25 mm/s

 

[th3o 0]

The bed leveling seems OK.

Reading this thread https://umforum.ultimaker.com/index.php?/topic/4586-can-your-um2-printer-achieve-10mm3s-test-it-here/page-25 I found out that the screws on the head where too thight.

Maybe this hasa something to do with it.

I will try to print it again and see if thing have been improved.