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Hey guys been struggling with my Rostock after replacing the hotend. I'm getting a ton of stringing mostly on the supports. I tried adjusting the temp down to 185 from 190 and it started underextruding so I don't think its a temp issue.

parts turn out good but the stringing only started after replacing the hot end any ideas?

I'm using simplify 3d

190 degrees

default 2000 print speed

x/y movement speed 9000.0

[img]http://i11.photobucket.com/albums/a182/deadpool2099/stringy_zps58dpq4mu.png[/img]

Seems like you will need to adjust your retraction distance (I would increase it by 0.5mm until it goes away). Also, using the "coast at end" option in Simplify 3D helps a lot with stringing too. I have mine set to 0.2mm as the coasting distance.

Strings are usually retraction, and the tree branches that are growing off of some of your supports are generally attributed to the extrusion temp being a tad too high. Print a few of these to get things dialed in just right for that particular filament. http://www.thingiverse.com/thing:607968

I almost wonder if the thermistor is off as these temps and retraction settings were fine with the old hotend before it broke.

Once my current print finish Ill run some calibration prints.

Any suggestions on the trail coming off of the top? It goes al the way up to the hot-end, and it happens for every print I do. HE at 230C and Bed at 90C
[img]http://i.imgur.com/AK1QWt3.jpg[/img]

Anyone care to share their simplify 3d settings with me?

Ok, I think I have the stringing nearly figured out.
However, I have a new issue that has me a bit stumped.

[img]http://i.imgur.com/B62Yx9p.jpg[/img]

What might be causing the voids?

Info
Matterhackers PLA White
HE 199°C Bed 60°C PEI
Retraction 6.5mm
Extra Length -.1mm
Z-lift .5mm
Wipe On

That's a retraction issue, most likely you have too much or it's too fast.
If you retract too much, you can end up where filament takes time to get back to the nazzle because of the backpressure combined with he hysteresis in the bowden tube.
If the retraction is too fast, you can loose steps on the prime portion because of the increased pressure resulting in a small void.
The wrong way to fix this is to add extra filament on the prime, which I've seen people recommend, the problem with fixing it this way is you added additional volume to the extruder which is going to have to show up somewhere on the print.
I don't have a HE280 si I can't recommend settings, but I would start with short slow retractions by which I mean <2mm @ <20mm/s, unless you end up needing a lot more retraction than that, I wouldn't touch the speed.
KissSlicer lets you set independent retract and prime speeds, but I don't think any other slicer exposes this.

A negative extra length on restart is definitely not going to help with voids.

Min. layer time to perhaps 10 may help on the smoke stack.