Bridges and blobs in a print

[luiss]

Hi.

Attached is a picture of a common part (Thingiverse part "8mm_0.92_thumb_screw") printed twice.

The left part (black) is printed with another printer, displayed for reference, and the right one (gray) is printed with my Prusa i3.
Although there are other problems, int the printing, I want you to look at the strings and blobs between teeth.

I have tried everything from reducing extruding factor (up and down, from 0.9 to 1.1), to change speeds (down to 20mm/s), ...

My printer is a Prusa i3 (steel version) with Budas-like extruder. I am using ABS 1.75mm. I have measured it and the actual diameter is 1.68 to 1.71, so I have set it to 1.70mm. I print at 235 C. I use a heated bed at 80 C, although I have tried it also to lower temp (down to 30 C), using hairspray to hold the part in place.

I am using Slic3r version 1.0.0.RC2. On the printer there is a Marlin v09.

Would anyone tell which setting might I use to try improve or perhaps remove that specific problem ?

Luiss.

print1.jpg

[RobH2]

Just saw this. Did you ever figure out your problem?

[richardphat]

Can be lot of problems, such as overextruding, the nozzle itself is leaking and melted plastics get in contact with your print, most of the time even if you calibrate it well, it will be a slicer problems.

Because that would be the zone where the movement start its cycle .

[luiss]

I reduced the speed to half. Although still there are blobs and string here and there, it has improved a lot.

[Davo]

Have you tried lowering your print temperature at all? Slower print speed should allow for a slightly lower temperature, and your material should be less... flowy.

Also, have you tried increasing the cooling? Should have the same effect.

[RobH2]

'luiss', do you have any more photos, maybe some new photos and a few different angles? It always helps to see exactly what is going on. You are getting some good comments but a few photos might help zero in on the culprit.

[3dkarma]

One of the causes of blobs and strings is oozing from the print head when changing layers or moving from one part of the print to another. You can get rid of them by tuning your retraction length.

Printing at too high a temperature can also can also cause problems with small objects as individual layers don't get enough time to cool properly. Try printing two of the same object at once.

[RAMTechRob]

Download the new version of Slic3r. It helped me tremendously with blobs and extra stuff.