Gcode help

[Isaac Thompson]

upgraded my TAM 2013 to a hexagon hot end, with GREAT results. however, the way i have it set up now, the fan only blows on the hotend barrel and not downward at all (usually this isn't a problem, as the ambient room temp is only about 60 degrees)
however for very small parts, there just isn't enough cooling time, and setting the layer time to be greater isn't a good solution because the hotend still conducts heat down into the part. my idea is to add some gcode on the N layers tab, and set N layers to 1.

it should go something like:

 retract the filament (to prevent ooze) 

bring the nozzle up a few mm,

 come forward to the front of the bed,

 sweep back and forth in the x direction a few times, (this will direct some airflow back over the part)

return to the previous X,Y coordinate

return Z to where it left off

prime filament

continue printing

i think i know how to send the head to absolute coordinates, but i'm not sure about relative coordinates

[funBart]

I have done something like that in the past to make a Ooze wiper working, but first, what isn't clear to me: is your printer working with absolute or relative E normally?

BTW: although you have to do a Z lift when cooling, do you want small extruder fan do the blowing, as I simply attached a ordinary 12cm computer fan to my printer: that way the PLA is cooled hurricane style the whole time.

Bart

[Isaac Thompson]

Firmware type: 5D Absolute E

i want to use the small extruder fan, because i don't normally print things with very small volume anyway, so an extra fan would just get in the way most of the time. i think really all it needs to do is just Z-lift, and then move directly forward in Y, without having to sweep back and forth. and then delay perhaps 5 seconds, and then move back and resume printing. 

thanks for your help!

[funBart]

I suppose something like this: of course: change the position of the front of the buildplate according to your printer, depending of the size and where the centre of the zero point is positioned). Same for the value you use for extra prime and suck at layer change (now set as 1 and 1.1mm.) Also, set the speeds normally used. The F value is in mm per minute, so 50 mm/s is F3000

G1 Z<Z+3> F600 (lift the head 3mm)

G92 E0 (reset the E value)

G1 E-1 F600 (do an extra 1mm retraction)

G1 X0 Y-75 F2400 (go to the front of the buildplate 40mm/s)

G1 X100 Y-75 (go to the right)

G1 X-100 Y-75 (go to the left)

G1 X100 Y-75 (repeat go to the right)

G1 X-100 Y-75 (repeat go to the left as much as needed)

G1 E1.1 F600 (prime the nozzle again)

G92 E0 (reset the E value again)

G1 X<NEXTX> Y<NEXTY> F2400 (go above the next to print place)

G1 Z<Z-3>  F600 (lower the head again?)

I don't know if that last line is necessary, as the next G1 command probably will contain the (new) Z value.

You can repeat the sweep movement depending how much time you need.

When not seeping at all you can use the G4 command (dwell) followed by how long (ms) you want to wait.

G4 P3000 is wait 3 seconds. Or in seconds: G4 S3.

Check if your firmware actually is using all that (common) commands.

Check the Gcode output first in Repetier Host, as the travels are visible there as well, to check if some command is sending your extruder crashing into a wall....

When using relative coordinates you have to use the G91 command, after that you can do whatever relative moves, but you have to do the math so that when ending all that relative commands the position of the head is exact the same as before the G91 command.

To go into absolute coordinate, use the G90 command.

Hope this gives a start.

Bart