Custom Start G-Code - Prime/wipe pattern

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Custom Start G-Code - Prime/wipe pattern

Postby KC_703 » 2014-Sep-Mon-17-Sep

Hello,

I'd like to create a custom start which prints a simple pattern to prime and "wipe" the hotend. The following code performs the basic home XY&Z, auto-level then starts my 3 line pattern. I'd like to make sure I understand the E (filament extruded in mm) and F variable settings with E being the filament to be extruded, and F as the feedrate.

G1 Z.19; move to first layer height
G1 X140 Y2 F1500.000; move to front right corner of bed X140 & Y2 adjust feedrate to 1500mm/min
G1 X140 Y30 E15 F1500.000; Line 1 - Extrude (15mm) down Y-axis 30mm
G1 X142 Y30 E2 F1500.000; Shift 1 - Extrude (2mm) across X-axis 142mm
G1 X142 Y2 E15 F1500.000; Line 2 - Extrude (15mm) down Y-axis 30mm
G1 X141 Y2 E2 F1500.000; Shift 2 - Extrude (2mm) across X-axis to 141mm
G1 X141 Y60 E30 F1500.000; Line 3 - Extrude (30mm) line down Y-axis 60mm

Maybe, I've oversimplified this process in trying to generate the g-code. I guess I should create a STL, slice and copy the g-code...
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Custom Start G-Code - Prime/wipe pattern

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Re: Custom Start G-Code - Prime/wipe pattern

Postby RetireeJay » 2014-Sep-Mon-19-Sep

How did you calculate your E moves? They are far too large.

What you should do is first calculate the volume of the trace you want to leave behind.
For example, your first printing move is 28mm long. If you have a 0.4mm nozzle and want to leave a trace 0.4mm wide, that's the second dimension. Then if your layer height is 0.19mm, that's the third dimension of a very long and thin "brick". So the volume of your "brick" is 28 X 0.4 X 0.19 = 2.128 mm^3.

Now if your filament is 1.70mm diameter, its area is Pi * r^2 which is 3.1415 * (0.85)^2 = 2.270 mm^2. So in order to extrude a volume of 2.128mm^3 you would specify an extrusion of (2.128 / 2.270) = 0.9806mm.
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Re: Custom Start G-Code - Prime/wipe pattern

Postby mechanizedmedic » 2014-Sep-Tue-04-Sep

Make the shape you want in an stl then slice it and copy whatever Gcode you want into the start code. Then you only have to make up the wipe portion.
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Re: Custom Start G-Code - Prime/wipe pattern

Postby KC_703 » 2014-Sep-Tue-21-Sep

Thanks! I've since done a few prints and adjusted the E... they were way too high and instead of a line, I was getting a nice thick extrusion. I'll digest the formula above.

As for making the shape and copying a layer of code, that was definitely my next step.

So far though, the pattern is working for the most part... but definitley needs tuning.


Again, I appreciate the input!
Ken
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