"Bulbs" on Print.

I’m not sure if this is the right terminology for what’s the in attached picture. So I’m having a bit of trouble determining the cause. I did recently switch from a Black PLA to this Grey PLA and generally had no such issues with the Black. From the research that I did do, I think this MAY be due to an issue with the Slicing Software (using Cura). That said, I’m also looking for a more technical understanding as to what is happening here?

About this print, I can print it great as a single continuous run. It’s only when the head “hops” from one section to another that it manifests. These “buttons” were printed at the same time on the same run, both look identical on the top and the bottom in terms of their output (which is why I took the picture as shown, so you can see both). Also, it should be noted that the “bulbing” doesn’t realy start until it his the incline.

Again, I’m looking for a greater understanding as to why this happens (in terms of what the hardware mechanism is that causes it). Second what would the recommendations be on solving this in terms of getting a better slice output (assuming that’s the issue).

I’m using the TAZ 5, 205C, PLA. Cura to slice.

Thanks much!

Looks like it might be over-extruding to me. Did you measure the diameter of the filament you’re using and input that into Cura?

Overextrusion looks like it could be a part for sure. Also you might be running into temperature issues. Lighter colored filament melts at a lower temperature (something to do with the dye additives and the chemical makeup) so the temperature that worked fine for black might be 5 degrees or so too warm for the gray stuff. Also, if you don’t have the cooling fan enabled or turned up high enough you can get a pattern like that. Definitly check and adjust the filament diameter first, but then play with the temperatures and fan settings and see if that helps any.

Thanks to you both for your assistance! I did do some temperature checking and I believe I’ve found the problem, but before I get there I can verify that I dropped the temp from 205C to 190C and was getting a much better laydown. That said it didn’t fix the problem! So I did a bit more research (also was not the filament diameter).

I found this from MatterHackers (http://www.matterhackers.com/articles/how-to-succeed-when-printing-in-pla)…

“The outside edges of my parts have lots of little bumps on them.”

Make sure your printer is getting enough data. If printing from a computer, ensure that the computer is not too busy to feed the printer commands. If the printer is pausing it is usually due to the printer being too busy.

Print from SD card. On some printers you can try and print from SD card. This often helps the printer have enough data to run more smoothly.

Source better PLA. We have found that the quality of your print material can have a big impact on the quality of your part. Getting better PLA can help you get better parts. However, don’t be too quick to assume the problem is in your PLA. With the right settings and patience hobbyists have succeeded in printing all sorts of materials many of which have very low viscosity and inconsistency. You should be able to get at least usable parts even with some lower quality filament.

The first one was it! I was having a background process interfering with communication and therefor stopping the printer at random locations… thus creating those little bulbs. Need to kill background processes for longer prints!

Thanks again, just wanted to share the “fix”.