And I just did a print, with two raft layers. the second extruder always hits the material and raised the nozzle level for both extruder. this made everything worse, because the extruded material can not stick properly to the bed, and made the thread thinner than normal width, so the threads can not bond together. I have also included the photo.

Has anyone experienced this before? I am thinking maybe the two extruders are not leveled.

Thank you for your help!!

Thank you so much guys!

My current setting for hot end is 220, and 100 for print bed. I think I need to calibrate the Extruder, I found out yesterday that the step motor is not extruding the right length. instead of extruding 100mm, it extruded 128mm, So I have to make changes to the firmwares first, and then try a few tests.

Based on the video for Extruder Calibration,  I need to update the firmware.  Or I can simply change the Extrusion Multiplier, In my case, I will have to change to 0.78. But I am wondering which way is more efficient for future replacement of filament?

Both Nozzles seems like in the same level, the problem is, not only the second nozzle contacts the printed material, the main Nozzle also drag through the printed material (which is cooled down and created rough surface). So I am thinking maybe I over extrude too much, or the over lap is too much so the material was squeezed up after extrusion. But if I don't extrude this amount, the filament can not stick to the printbed, and it is another problem.

If you have to overextrude to stick to the bed then your bed is not properly calibrated. Ideally the gap between your bed an nozzle should be at the maximum of half your layer height. To ball park it you should be able to place a piece of paper between the bed and nozzle and just feel the paper slightly drag between them. Even better, use a .15 or .10 feeler gauge.

https://solidoodletips.wordpress.com/20 … libration/

and

https://solidoodletips.wordpress.com/20 … flow-rate/