How to change initial starting purge (nozzle wipe?)

[Milestone85]

How would i go about changing how when a print starts the extruder purges (or pushes out) out so much filament. Now it is squirting a big line of filament just off the side of the bed, then the nozzle moves to the print table and cleans the filament off. Before it used to go to the corner of the print bed, push out a big blob, then quickly clean it off as it slid across the bed. Id like it to go back to this method, i find the current method where it extrudes a long bit of filament and then swipes over the bed to be troublesome, sometimes the filament will not fall off the tip, it get stuck to it then ends up on the print model at the starting layers.

[adamcooks]

Did you ever find which line of gcode was doing that? i have a larger then my heated bed glass plate and the purge is causing some difficulties.

[nxumdon]

Can you post your starting gcode...this will probably show the issue.

Thanks

[KC_703]

Could this be machine specific?

My Printrbot Simple Metal doesn't perform the starting purge/wipe. So I added a startup script to print a few lines of filament after the auto-level procedure.

I've read that this is a normal function of Ultimaker machines... so possible a recent firmware affected what you're experiencing?

[dsegel]

Could you share the code you use to print those first few lines? I'm running into the same problem myself (also with a Simple Metal) and was thinking of doing something similar.

[adamcooks]

theres a line in the start gcode that calls for priming

mine says "G4 P3500 ; purge nozzle" i just put a semi colon in front of it and it stopped that

[dsegel]

"G4 P3500" just makes it wait and do nothing for 3.5 seconds before continuing. It doesn't actually extrude or retract anything. I suppose if you had a large amount of ooze it would let it happen.

[KeyboardWarrior]

theres a line in the start gcode that calls for priming

mine says "G4 P3500 ; purge nozzle" i just put a semi colon in front of it and it stopped that

If you wanted to extrude 35 mm of plastic (which is a lot), it would be G1 E35 F225

I would recommend purging about 15 mm of plastic, G1 E15 F225

F225 is pretty slow, but I'm not extremely familiar with the PrintrBot's extrusion rates, so 225 is pretty safe.

[TenKOhms]

If you wanted to extrude 35 mm of plastic (which is a lot), it would be G1 E35 F225

I would recommend purging about 15 mm of plastic, G1 E15 F225

Like KeyboardWarrior said, the G1 E15 F225 will do an initial 15mm extrusion of filament if you put it in the starting G-Code. For PrintrBot Simple, or printers with an auto-bed leveling probe, I would suggest this for a starting G-Code Script to home, probe, and purge correctly:

Code: Select all

G28 X0 Y0 ; home X and Y axis
G29 ; initiate z-probing
G1 X0 Y0 Z.10 ; move to corner of bed
G92 E0
G1 E15 F225
G92 E0

[gelly]

how can i purge both extruders and not just one ? what is the code that selects the active extruder ? so i may be able to add that into the starting gcode script ?

thanks