UM3: G280 making a mess

[kfsone 5]

Not sure if it's just me or if Prime Blob behavior changed recently:

Instead of a little bullet/drop it produces a small base and a taller tower, and then the print head apparently tries to wipe the nozzle on the tower *and* prevent stringing by moving downwards and towards the print as it goes.

 

At lower temps and with extra adhesion, I can generally get away with this, but most of the time what happens is that this knocks the blob over, catches it on the base of the print head/silicone nozzle cover and then enters one of a number of not-good scenarios.

 

Mostly it just drags the blob into the print, other times it drags the string far enough to overlap some part of the print, or if the head moves slowly enough, it doesn't quite break the string before reaching the print and the print manages to yank the cooling prime out of the nozzle.

 

Here's an example where I got lucky, the blob just sticks to the bed, but the nozzle left a long string 1/3 of the way across the plate to the build.

http://www.kfs.org/oliver/images/um3-blob.mp4

 

Why do the wipe *towards* the print? Wouldn't it be better to do the wipe out to/past the edge of the bed and then come back? Why is the prime thinner at the top now?

 

[Matioupi 1]

Same behaviour here. The PLA blob usually stay in place, but for my dual extrusion prints, the PVA one is almost always carried toward the print area...