Recurring Blob Pattern

[wbailey]

I'm getting an odd repeated pattern of blobs that only seems to occur on certain surfaces, usually curved ones.



It's hard to tell, but I think I have seen the extruder moving in odd ways on maybe 1 layer out of 30, seemingly as often as the blobs occur. It seems to jerk in a different direction from the smooth curve it is tracing.
This pattern stays exactly the same across the 5 prints I did while under the mistaken impression that it was layer ends causing the bumps, and always is in the same area and only present on one surface.
The pattern stays the same even with infill at 0% and random outline starts on or off, which is what lead me to believe it was not outline start/ends.
I will see if I can catch the odd movement on a preview.

Model pictured: The first 10mm of http://www.thingiverse.com/thing:59918 fist only model.

Edit:
I played around with the preview and found this:


notice the bumps where there should be a smooth curve. Is this a defect in the model itself? Or is it a secret message in braille?

[wbailey]

I tried another model and got bumps there too:

http://www.thingiverse.com/thing:77952 scaled 10x

I just checked and these spikes are present with and without radial arc compensation

[sir-mike]

Uncheck arc detection in your g-code tab. That should do it

[chuck12]

I've been fighting the same problem for quite a while when printing round or curved objects sliced with Slic3r 9.8 or Creator, I'm glad you posted this
because Creator allows me see it is not hardware or firmware issue. If I turn off random line starts I find line starts and stops (are not) the only cause
of the bumps, I could actually watch prints sliced by Slic3r randomly placing tiny blobs on perimeters, perhaps for bonding inner and outer shells.
I've been wondering if these are actually artifacts generated by some CAD conversions to STL. files because prints I've done modeled with true
solid 3d software seems to have fewer problems altogether.

[wbailey]

Uncheck arc detection in your g-code tab. That should do it

I tried another model and got bumps there too:
-snip-
I just checked and these spikes are present with and without radial arc compensation

I just double checked, this does not eliminate the blobs/spikes.

I've been fighting the same problem for quite a while when printing round or curved objects sliced with Slic3r 9.8 or Creator, I'm glad you posted this
because Creator allows me see it is not hardware or firmware issue. If I turn off random line starts I find line starts and stops (are not) the only cause
of the bumps, I could actually watch prints sliced by Slic3r randomly placing tiny blobs on perimeters, perhaps for bonding inner and outer shells.
I've been wondering if these are actually artifacts generated by some CAD conversions to STL. files because prints I've done modeled with true
solid 3d software seems to have fewer problems altogether.

Perhaps you could make a test cylinder for us to try with whatever program you're finding less problems with?

Also, here is yet another test:
http://i.imgur.com/VAC8s2c.png
The model: http://www.thingiverse.com/thing:46287
And the profile used to slice it:

spikes.fff

(2.38 KiB) Downloaded 602 times

[wbailey]

Here is something interesting:
http://www.youtube.com/watch?v=AFdcTiJqNus

I turned G2/G3 on just to see what effect it would have on the blobs even though I can't yet print with these commands. It seems the layers with blobs are not detected and replaced by arc detection.

[chuck12]

I have to correct my earlier post about less problems with solid modeling software, I was printing with semi-transparent blue pla and blobs were nearly
invisible with dark shiny pla they are there.

[crank]

I am having the same problem on my M2. However, I have a hypothesis that it is related to .STL generation and what software/settings that are used to generate that .STL . I have downloaded a couple of models, circular in nature, from Thingiverse and they print completely fine. However, any of my own models that are circular in nature, done with SolidWorks 2013, have the same recurring blob pattern(RBP syndrome) no matter what. Anything that is NOT circular in nature, prints just fine even when I model it in SolidWorks 2013.

Try printing http://www.thingiverse.com/thing:32203 and see what you get. I used it on calibrating my Lay Woo-3d filament prints and I am now using it to tackle RBP syndrome using PLA. I had no recurring blob patterns when printing that thing in either PLA or Lay Woo-3d.

[wbailey]

I am having the same problem on my M2. However, I have a hypothesis that it is related to .STL generation and what software/settings that are used to generate that .STL . I have downloaded a couple of models, circular in nature, from Thingiverse and they print completely fine. However, any of my own models that are circular in nature, done with SolidWorks 2013, have the same recurring blob pattern(RBP syndrome) no matter what. Anything that is NOT circular in nature, prints just fine even when I model it in SolidWorks 2013.

Try printing http://www.thingiverse.com/thing:32203 and see what you get. I used it on calibrating my Lay Woo-3d filament prints and I am now using it to tackle RBP syndrome using PLA. I had no recurring blob patterns when printing that thing in either PLA or Lay Woo-3d.

I just test sliced this and the blobs/spikes are still present in the preview, they were probably just less evident on your print for whatever reason. I've yet to have a single curved surface slice without the blobs appearing in the gcode.

[cdub]

I am having this exact problem as well. It seems to only occur on circular profiles. I am printing PLA.

I changed my settings from the default "medium" quality to the "high quality" and also unchecked the box for detect and modify circular segments and the problem went away.

However, I have a new problem that the ends of my parts are not "capped".