Prime blob problem

[tmcolby 2]

My UM3 started doing this weird issue after it prime blobs extruder 1. I've been using the same settings profile, and now for some reason it leaves a long streak of material all the way across the bed. I am printing on a raft. Any ideas? 

 

After the blob, it does a very slow move to back corner extrudding the whole way.

[tmcolby 2]

ok, after a bunch of testing.. the problem manifests when i use "max comb distance with no retract"

 

my stock settings profile works as it used to.

if i plug in a value of 10mm into "max comb distance with no retract" the problem shows up.

 

whats up with that?  does anyone else use that feature with success.  i swore i had it working before and i really liked it because i like to print my parts on a raft of breakaway material to get a consistent surface texture.  this feature would leave the raft pristine so i dont get any strands in my surface layer of my print.

[michelide 4]

Is this a dual extruder print?

[tmcolby 2]

yes, it is.  

 

i did determine that i was applying the setting to extruder 1, when i should have been applying it to extruder 2.  

 

none the less, it seems like a bug.

[michelide 4]

If there is no retraction the material will continue to heat in the extruder and melt out. If the retraction is too short an amount of material will still heat up and drip out. It seems that reducing the temperature slightly  and retracting by an exact amount is necessary to keep the material of the not in use extruder from dripping all over the place. Do you think the red line could be because the material is slowly melting out of the extruder? The strange thing is that the red material seems like a somewhat even extrusion.