Prusa I3 Bad printing

[kapusta]

Hi guys, don't know if this is right place to post this, but here it goes:
I'm using Prusa I3, and I'm kid of new to 3D printing. I use to get ok-good prints on the start, but not any more. I use Cura, and this settings (pic bellow). So I realy don't have any idea what to do more. I try to calibrate it as much accurate as possible and tried different settings. Any advice or solution for this problem? (model pics bellow)
Layer hights 0.1-0.2
Printing temp 185-195
shell 0.8-1.2
Thanks!
p.s. I'm using chinese filament which I get with printer.I know that is a problem but not as big as my prints are bad. And I did get some good prints on the start.
IMG_1006.jpg IMG_1007.jpgIMG_1008.jpgIMG_1009.jpgIMG_1010.jpg

[kapusta]

IMG_1010.jpgIMG_1011.jpgIMG_1011.jpg756adc9f-8013-41c7-b5f4-b9ff0ffaef02.jpg3cb0a30a-2e06-498a-8fa9-818b2e2095b3.jpgIMG_1013.jpg

[Alibert]

It is hard to see, but it looks like small steam bubbles. This can happen when your filament absorbs too much moisture. Try some dry filament to see if it improves. You can take off a length of filament to have a go at drying yourself, or buy a new roll and try that.

PS: with a cheap usb microscope you can have a better look

[kapusta]

Thanks Alibert, I'm buying a new filament in monday and try that

[3dex ltd]

Yes I would say moisture issue too. If you want to avoid it:

1. Buy high quality filament that is less prone to absorbing moisture
2. Store your filament in an air tight container when not in use
3. Before printing dry your filament out in the oven at a heat of around 50-70deg.

These are just some methods of avoiding steam bubbles

[kapusta]

Thanks 3dex for advices, and how about this model, do you think moisture was also a problem?
IMG_9430.jpg

[Alibert]

Could be both over-extrusion or steam bubbles. If a lot of small steam bubbles are generated, the volume of the extruded plastic increases too. With an USB microscope you can better see what the problem is.

[kapusta]

Hi, i bought a new filament, black 1.75mm Devil design. That fixed bubbles, but now I have problem with over extrusion. How can I fix that?

[kapusta]

IMG_9441.jpg This is model printing right now

[Alibert]

Either over-extrusion or your z-steps (how many steps are needed to move the nozzle 1 mm vertically) is wrong in your firmware.

The first you can solve in the slicer (Cura). The latter needs to be corrected in the firmware settings.

A quick check for the latter is to move the nozzle to the front of the build plate and height z=0 (nearly touching the build plate). Then manually move the the nozzle 100mm vertically (z->100). Measure with calipers if the distance is indeed 100mm. The manual moves can be either from your PC (gcodes), or from the display controller (there should be a move or jog menu). If the distance is different (80mm for example), then you need to calculate and adjust the firmware z-steps setting.