Small repeating blob on inner perimiters

I’ve had a really fairly minor issue with my prints for a while now. Basically any time I print something that has an inner hole, the place where the nozzle starts and stops on that hole tends to have a tiny bit of extra material extruded. It doesn’t seem to do it so much on the outer perimiter. It generally does it every layer, at pretty much the exact same spots, one per hole usually, though occasionally for some reason I can’t explain, i’ll get two of them in some holes. The extruder itself is pretty much 100% dialed in, I extrude 100mm filliament, the filliament moves 100mm, the first layer height appears to be fairly good on average, and the correct thickness of the first layer does not seem to have an effect on the issue. A smaller hole is more likely to have the issue occur. Typically the little blobs will be stacked on top of eachother all the way up the hole in that same spot.

Any ideas what is going on or how to fix it? I’m thinking it has something to do with retraction on permiter start or stopIncreasing or decreasing the number of perimiters has no effect. Randomize starting points doesn’t seem to help, though typically it enters the inner perimiters in the same spot even with that on. Right now retraction is at 1mm, retract on layer change, and minimum travel after retraction 2mm. Wipe before retract is not enabled. I’m not even sure what that one does. Printing with a .5mm nozzle, standard .5mm settings from lulzbot, etc.

Am I on the right track, or is this something else entirely? potentially something related to the budaschnozzle 1.0 design itself that isn’t present in newer ones?

It’s a fairly minor issue and easy to clean up, but I’d like to get it working correctly if I can. Thanks!

Hello!
What Slic3r version are you using? You might want to try with the 1.0.0RC2 version that I just released (find it at http://slic3r.org). If you have been using 0.9.10b it could just be caused by an old bug in there.

If you’re using 1.0.0RC1 or 1.0.0RC2, I would then look at the G-code closely with a preview program like Pronterface. Is there anything visible in the inner holes where the printed object has the said blobs? If there is, it’s a toolpath issue and we could proceed troubleshooting together. If there isn’t, and the holes look round and smooth with no artifacts, it’s usually a matter of temperature and/or retraction speed and/or retraction length.

Let me know how it goes. :slight_smile:

Hi there!

I was indeed using the 0.9.10b variant, which was embedded into repetier. I’ll try upgrading to 1.0.0 RC2 and see if that fixes the issue. The toolpaths all looked correct from what I could tell. I’ll give the new slicer a shot and report back on my findings.

As a side note, Slicer is a wonderful program, keep up the good work!

That fixed it! Upgrading slicer seems to have resolved the issue entirely. I can still see where the inner perimiter starts and stop, but it’s bairly even a surface ripple now. That also seems to have generally sharpened up my overall prints, and it got rid of another minor issue relating to infill in a thin wall section that I was seeing but thought was just something off in my settings. Definitly a major improvement all around. Thank you very much for taking the time to help me out with that!