Oddness / sequential prints

[morgandc]

I am trying to figure out why I can print one perfect object in the middle of the bed, but when I do sequential duplicates of 2-4 there is almost always something wrong with a them. One layer line that is shifted, a wall that is mucked up for several layers, etc.

I am able to lay down a even first layer and the motion appears smooth going around the calibration ring edges. The only thing I can think of is the spool is causing an issue, or some motion issue. Most of the object is fine, but an inch up or so you may have a layer or few that is not up to par. In watching the Octoprint 7 point calibration script the motion doesn't seem as smooth as it should between points, but when laying down the calibration ring everything looks great.

-Dwight

[Qdeathstar]

if you print an object that is the same physical size as 4of the objects you are printing, does it have similar issues? If so, coulld be calibration problems. Errors for delta printers get larger the further you are from center.


But what it mostly likely sounds like to me is issues with retraction (resulting in jamming (under extrusion) and back pressure (over extruding) during your print. When you print multiple objects you do a lot more retraction, since you jump from part to part and retract each time.

I'd lower my retraction distance and speed and see if the results improve.

[morgandc]

I am printing sequentially, so it finishes one part, then starts another. Really, the same as printing one part in a different part of the bed to avoid stringing.
I did lower the speed significantly with not much of a noticeable difference.
I was trying to think of a calibration issue that would make one maybe two layers off in the middle of a sidewall curve. I would think that a calibration issue would ease in and out, or be consistent on the whole section of the print?

[morgandc]

Hmmm, still looking for ideas.

[Qdeathstar]

Yeah, I'm sorry. I missed the bit about sequential.... I kinda still feel like it might be a issue with calibration.


However, you also noted that it starts once you are a ways away from the bed. Well, your bed is heated (right?) and your print head moves further away from the heated bed, into cooler air, and now the hotend has to work harder to prevent temperature swings.... maybe keep track of your temps during the print....

I'm surprised McHackney hasn't posted yet. I'm sure He knows the Answer.

[morgandc]

I think I tried it enclosed, which would completely change the temp. Also, I would think that any temp issues would effect printing in the center as well?

[Qdeathstar]

The center of the bed is more insulated from the outside world than the edge of the bed...

[morgandc]

Well, this appears to be mostly a speed related issue. If I do the perimeters at 15 mm/s the quality is that of the center of the bed. The clue was it happened once in the center of the bed during testing. Not happy, this PLA material is more sensitive than the ABS I was using before...

Not sure what issue speed is exacerbating as 98% of the part is fine...