extrusion issues with rostock v2

[nU.metA]

Hello,

We are currently attempting to print a few test objects with our printer and are having some extrusion issues with our filament. Around smaller, more detailed areas the printer tends to leave globs, minor stringing, and even scorch marks. Around the larger areas and base areas it tends to be decent quality. We are printing with an extrude temp. of 218 C and a bed temp of 80 C.


Here is an example of what our prints are looking like. Keep in mind, this isn't the first thing we've printed, and have had varied results depending on the piece:

[Nylocke]

What material is that? Are you using Materslice or Slic3r+Repetier host? There are numerous tweaks you can try to resolve these issues, but what probably would help the most is slowing the print down.

http://forum.seemecnc.com/viewtopic.php?f=36&t=7361
Michaels guide is a good thing to check out in general.

[nU.metA]

It's ABS, sorry i forgot to mention that. We're using mattercontrol. we'll try slowing down the print as suggested. Any particular speeds we should be applying for the type of piece pictured?

[Nylocke]

What speeds are you using currently? I would advise doing a z-hop or z-lift of 1mm, that should help with the nozzle dragging on the print (that's where the burn marks are likely coming from). Also you might do well to increase the nozzle temp to 225-230, 218 is a bit on the low for ABS, I think slightly higher temps lead to less stringing with ABS (key word is think, I may be remembering wrong). My lowest temp I print ABS at is 230, though the SeeMe hotend has a bit more thermal mass so you can get away with lower temps to an extent.

[IMBoring25]

Cooling settings with a minimum layer time should help, but as small as some of those layers are you'll have to slow down dramatically. Another thing that can be done, rather than just slowing down the print to almost nothing, is to make more than one copy or make something else of equal or greater height at the same time.

[DanHall]

A couple of other settings you can play with are the retract and wipe. Both could play into the blobs and strings.

Funny Nylocke, I always associate stringing with higher temps... Maybe I need to play, I mean test, conduct serious scientific tests (it's my story and I'll tell it like I want to), with higher temps. We are usually printing a voronoi pattern so there are lots of open spaces for stringing. We don't get many but there is always room for improvement!

[Nylocke]

And I can confirm my above stated statement (redundant, yes) is true. From the KISSlicer subfourm, MHackney was talking about print temps and stringing/blobbing. PLA is the *only* (may change as we dive further into more materials) plastic that gives less stringing when printed cooler from his experience. I think JFettig has confirmed that higher temps on ABS result in much less stringing and blobbing. Also better layer adhesion and other things. I can't remember where Jon said the things about ABS but I can give you an exact post for the PLA bit if anyone is interested

[JFettig]

Usually when ABS strings, its because of extreme nozzle pressures, that has been my experience. You end up with a thick string at the start of the next path. Increase the temps and nozzle pressures go down. This is all dependent on print speed too - basically you need to get the material up to temp to extrude at the rate you're extruding, higher rates require higher temps to get the plastic to proper temp. I have some natural PETG that shows this very well, if the temps are not high enough for the speed, it extrudes it a gross white color.

I think PLA will behave the same, I never ran PLA under 200C for very long, it will definitely print at lower temps but probably not at high speeds.

Retraction distance is primarily to relieve nozzle pressure, at high speeds and low temps, you end up with high nozzle pressure, but if you retract enough, it shouldn't string. You could end up with 10mm retractions at the cold end but at the hot end it might only be retracting 2mm due to compressed filament.

[nU.metA]

Thank you all very much for the suggestions and input!

We're playing with temps right now, and after we have that worked out we'll play with Z-hop/lift.

We really appreciate the help.

[nU.metA]

We've played with the extruder temp., the z-lift, and the speeds for infill, perimeter etc. The print itself looks better on the outside faces, but on the inside we are still getting lots of artifacts. This has been the one constant the entire time. Why do we only get artifacts on the inside of the piece (during the end of a print move)?

[Nylocke]

You might have cooling issues like this person http://forum.seemecnc.com/viewtopic.php?f=37&t=8011. Try printing 2 of them at a time, with another object, or a bit slower. What speeds are you using for outside perimeters? It helps if they are quite a bit slower (1/2 or slower) than the rest. I've gotten some pretty nice looking things by doing this.