Pre-Printing Extrusion

[hiltonmw 0]

Hi Guys,

This may be a wayyyy newbie question... when I print files on my Ultimaker 2+, it heats the buildplate and the nozzle appropriately, and then it "pre-extrudes" quite a bit of filament. Is there a way to dial back how much "pre build" filament is extruded? It seems excessive on my printer, compared to what my previous Makerbot used to do.

[tommyph1208 55]

Have a look in Cura under the tab called "Start/End-Gcode"

If you click the start.gcode file, you will see some lines of code that always gets added to the top of your gcode after slicing (it eg. homes the printer, zeros some values, stops the fans etc.)

There should be a line saying something like:

G1 F200 E3              ;extrude 3mm of feed stock

The number after the E is the amount of filament (in mm.,) extruded before the print starts, play around with that value.

Don't turn it off completely, the hotend needs to be primed so that process is not happening during the printing of the first layer... Otherwise you will get terrible bottom quality and adhesion problems.

I always print with 3-5 lines of skirt, which performs kind of the same function (It starts the print by printing lines at a certain distance around the perimeter of your model), but also will let you do a bit of "on the fly" bed leveling before the actual print starts...

Edited April 6, 2016 by Guest

[IRobertI 521]

The start and end code tab isn't available if you're using an UM2/UM2+ machine unless you switch the "Gcode flavour" in the machine settings in cura. I wouldn't do that unless absolutely necessary.

The amount of priming is set in the firmware for the UM2 so you'll have to re-compile the firmware if you want to change it.

[tommyph1208 55]

The start and end code tab isn't available if you're using an UM2/UM2+ machine unless you switch the "Gcode flavour" in the machine settings in cura. I wouldn't do that unless absolutely necessary.

The amount of priming is set in the firmware for the UM2 so you'll have to re-compile the firmware if you want to change it.

 

Alrighty then, I did not know that... I have seen it in my firmware for the UMO as well when playing with that... So which one counts for the UMO? That set in Cura, or the one from firmware?

[IRobertI 521]

Should be the setting in cura AFAIK.

[yellowshark 153]

Lol using Repetier Host I extrude 30mm of filament before starting the print to make sure everything is looking good, that is 30mm of perfect flow. If I get a nasty during the process, maybe a bit thin, I start the 30mm again. So not sure that 3mm is bad, apart from being too little

[yellowshark 153]

Perhaps I should add that this is done whilst the bed is at the bottom of the printer