Auto tip cleaning and priming?

[anon4321 16]

My prints always start a little ragged due to failure to prime the hotend and/or because the hotend has some gunk stuck to it or picks up gunk because the lack of priming underextrudes the outlines printed first.

Anyone good with GCODE? Could you spin some up to implement this:

 

Note I'm not talking about the out of level compensation! However, that is pretty cool and I believe already in Marlin.

 

[jameshs 42]

Which UM do you have?

On the UM1 I always wipe the hot nozzle and then spin the extruder wheel to purge the nozzle until it hits temperature when I whip away the extrudate before it homes into it

Not sure you can do this on a UM2

James

 

[anon4321 16]

I have the UM1 and I do the same. Even then, it seems to have difficulty starting the lines as if the tip is empty. Plus I keep burning myself on the hotend because it's well hot! ;-)

 

[skint 62]

One of the 3D printers we have in our company, a HP printer, has a small wire brush located at the back of the build plate. In the software settings you can program the nozzle to be dragged through the wire brush before the start of a print and also at any time during the print.

 

[illuminarti 18]

In the UM1 start gcode, change the line that pre-extrudes 3mm to extrude 6mm instead, and reduce the speed a bit (say F60).

Then add a G4 P2000 line after that to make it pause a moment. Then it's really easy to use needle-nosed tweezers to grab the extruded filament and move it out of the way. Finally, remember to use at least 3 passes of skirt around the print, to make sure that the filament is flowing nicely before the print proper starts.

 

[aviphysics 9]

Note: You wouldn't want to do what he does unless you have a glass bed. The plastic bed will get a divot in it if the hot end just sits around like that.

 

[illuminarti 18]

What who does?

[skint 62]

I think he refers to the video in the OP link illuminarti, the hot end resting on the build plate for a while.

 

[anon4321 16]

Yes, I have a glass bed.