Printing on right extruder connected to the left extruder circuit on Mightyboard

[Laurent Chenet]

Hi folks,

First, best whishes for 2016!

I have a "not so mighty anymore" board with a few "burned" connectors:

1) The USB is fried, but I'll survive through SD cards

2) The right extruder heater connector is dead (it first made my MB unresponsive then I disconnected the thermistor and it went back to life but no more volts on these pins)

I managed to take hundreds of prints through that board so I'm not ready to throw it away yet. Call it "sentimental". Also, I do not have 125 bucks right now.

So, what I did is connect everything to the left (unused, I'm not doing any dual stuff) while keeping the extruder on the right (I have this half-stepper config and I would prefer not to re-print everypart mirrored just because I have a dead connector...).

It prints fine but ex-centered to the right for 35mm. Normal but problematic.

In simplify3d, I created a profile, something called "FF Creator Dual Right Struder Plugged on Left", and I tried to update the starting Gcode so it would know that the nozzle is not where he believe but 35mm further on X axis.

Dilema: I cannot just move 35mm left before starting, because the carriage is already at minimum possible X position... I tried adjusting G92 A0 B0 to G92 A0 B35 but that didn't work.

Of course, the best solution would probably be a custom firware where A and B extruders are switched, but I'm not so good at that.

Any idea?

Thanks!

Laurent

[ealing2469]

Being a total non computer code person I would just off set the stĺ

35 mm on the virtual build plate. 

Sent from Samsung tablet.

[Dan Newman]

> Dilema: I cannot just move 35mm left before starting, because the carriage
> is already at minimum possible X position... I tried adjusting G92 A0 B0 to
> G92 A0 B35 but that didn't work.

A and B are the filament positions, not the extruder carriage position. What you
want to do is to change the home positions stored in EEPROM. Namely change the X
home position.

HOWEVER, if you are among the unfortunate who use MakerWare/Desktop, then you
may be out of lucj as they recall the home positions and then ignore them overriding
them with a G92 command. In some versions of MakerWare, you can edit the machine
profile to assert a different G92 command. However, some people have reported that
in recent versions of Desktop, doing that is much more difficult.

But you've indicated that you use Simplify3D so you should be okay. I've mentioned
the MakerWare/Desktop issue for folks months later reading this thread.

Dan

[Laurent Chenet]

Well.... Indeed. Surely the most univesal solution so far :-) And with latest version of S3D, I can drag them objects all at once. Thanks! (I'll still look for gcode tricks though :-))

[Laurent Chenet]

Thank, Dan, for showing me my error with A and B :-)

Back on tracks thanks to you, I figured out how to fix starting gcode script in simplify3d so left instructions are operating my "right extruder plugged on left extruder circuit output". The trick was to wait for the wiping so i can move it backward without hiting the X-min.

First I tried just G92 X145, but somehow it was almost hiting X-max doing that, so I prefered to "materialize" the 35mm back movement.

here is the code, bold part was added:

; **** Replicator 1 dual start.gcode ****

M73 P0 ; Enable build progress

G162 X Y F3000 ; Home XY maximum

G161 Z F1200 ; Home Z minimum

G92 Z-5 ; Set Z to -5

G1 Z0 ; Move Z to 0

G161 Z F100 ; Home Z slowly

M132 X Y Z A B ; Recall home offsets

M135 T0 ; Load right extruder offsets

G1 X-120 Y-70 Z30 F9000 ; Move to wait position off table

G130 X20 Y20 Z20 A20 B20 ; Lower stepper Vrefs while heating

M126 S[fan_speed_pwm] ; Set fan speed

M140 S[bed0_temperature] T0 ; Heat buildplate

M134 T0 ; Stabilize bed temperature

M104 S[extruder1_temperature] T1 ; Heat left extruder

M133 T1 ; Stabilize left extruder temperature

G130 X127 Y127 Z40 A127 B127 ; Default stepper Vrefs

G92 A0 B0 ; Zero extruders

M135 T1 ; Load left extruder offsets

G1 X-100 Y-68 F9000 ; Move to front left corner of bed

G1 Z0.3 F6000 ; Move down to purge

G1 X90 Y-68 E24 F2000 ; Extrude a line of filament across the front edge of the bed

G1 X100 Y-68 F180 ; Wait for ooze

G1 X110 Y-68 F5000 ; Fast wipe

G1 Z1 F100 ; Lift

G92 A0 B0 ; Zero extruders

M73 P1 ;@body (notify GPX body has started)

; **** end of start.gcode ****

; RECTIFY X POSITION 35MM SHORTER SO RIGHT EXTRUDER IS OPERATED BY LEFT INSTRUCTIONS

; (BASED ON LAST ABSOLUTE POSITION FOR X: 110 (110-35 = 75)

G1 X75;

G92 X110;

I guess I'll go with that as long as my board is alive, cause, anyway, all considered, with a dead usb port, I don't see any firmware upgrade possible... 

Thanks again!