Changing Z-Axis position for dump point?!

Hi everybody.

I just finished my Mendel and I am currently doing the first tests. Extruder works already and I can move all axis as desired.

My mendel has a heated PCB bed. It is quadratic and has no dump-cutout. Therefore I would like to set the X-Axis position to +30mm before do a pruge/dump before printing.
How can it be done? I would like to use the reprap host software - I knowit is possible with Skeinforge but I don't want to use this yet.

Anybody had a similar problem and knows a solution?

Thanx for your Help!!

Quote
Obi wan Kenobi
Luke, use the source!

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

I personally don't like that cutout since you lose build space. Skeinforge with the skirt or outline option turned on is the best way to make sure that the extruder is "primed" before starting the object.

Here's one way to do what you want with the reprap host. You can edit the g-code to insert a z-move upwards:

G1 F60.0
G1 Z30.0

and then home the z after the dump:

G28 Z0

Of course you have to be ready with your tweezer to remove the filament before it homes the z.

Edited 1 time(s). Last edit at 03/31/2011 10:12AM by brnrd.

Hi brnrd,

Thank you for your tip - just to be sure I do the right thing:

1. Generate G-Code out of desired STL-File
2. Open the G-Code file with editor
3. Insert the mentioned code "G1..." into my code like this:

; GCode generated by RepRap Java Host Software
; Created: 2011-03-31:00-34-22
;#!RECTANGLE: 
M110 ; Reset the line numbers
G21 ;metric is good!
G90 ;absolute positioning
M140 S115.0 ;set bed temperature and return
T0; select new extruder
M113; set extruder to use pot for PWM
G92 E0 ;zero the extruded length
G28 X0 ;set x 0
G28 Y0 ;set y 0
G1 F0.016; feed for start of next move
G1 X3.7 F3000.0 ;horizontal move
G1 X126.3 ;horizontal move
G1 X130.0 F0.0 ;horizontal move
G28 Z0 ;set z 0  <-- Here the Z-Axis is set to the 0 Position - can I move it there?
--> Else I would insert the first mentioned code-segment  here...right?
M109 S225.0 ;set temperature and wait
G1 F3000.0; feed for start of next move
G1 E1000.0; extruder dwell <-- this is the pruge process, right?
--> This is where I would insert the second code segment...?
G1 F0.016; feed for start of next move
G1 F18000.0; feed for start of next move
G1 E960.0; extruder retraction
G1 F0.016; feed for start of next move
G92 E0 ;zero the extruded length

is this correct?
(this is actually the file I generated yesterday...)

Thank you for your help!

Personally, I would write a batch file and use AWK, Perl, Python or Ruby (or any other script language that you may be familiar with) to do this automagically...

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

well... this might be the major problem...
I'm not too familiar with any of these languages.. I am happy that I even have some poor english knowledge

Why can't this just be added to the host software same as the X and Y-Axis setup? There you have the possibility to choose the point in the preferences.. would be nice to have the same for the Z-Axis... I think many people have the similar problem...

EDIT:

PS: But is it right the way I mentioned above?

Edited 1 time(s). Last edit at 03/31/2011 05:18PM by Elk.

Move the second g-code segment t(G28 Z0) o the end of the code that you posted after G92 E0. The stuff that happens before that is the extruder retraction to eliminate ooze. You want that before you bring the extruder back to z=0 or you'll lose more filament with the tip gets to the bed.

brnrd,
Thank you so much! I understand, will try this!
I think I will start the first trial priint tonight. I'll let you now if it worked like that!

Thanks alot!