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3D Printing >> 3D Printing and RepRap X2 Discussion >> Extruder-offset and homing out of bed
(Message started by: Ses4m. on Jul 8th, 2016, 11:49am)

Title: Extruder-offset and homing out of bed
Post by Ses4m. on Jul 8th, 2016, 11:49am
hi,
i have build a Dual-X-Carriage-Printer

after homing the distance between the nozzles is 280mm. i have to set the x-offset in Slic3r to 280?

x0-nozzle and x1-nozzle are not in a line they have a y-offset. I only have to set the y-offet in slic3r?

the homing-position of both nozzles are out of the printbed (35mm). How can i teach the printer that? it's not enouth to set the bed-shape in slic3r?!
my printbed is 210mm but the nozzle can move 245mm on X-Axis


Picture of my printer to better understand:
http://www.bmt.brothers-gaming.com/Sesam/bilder/dsc_0124.jpg

sorry for my english...

Title: Re: Extruder-offset and homing out of bed
Post by Denis Bakin on Jul 8th, 2016, 2:38pm
Nice machine.

If you are running Marlin X2 firmware, then the extruder offset is configured in the firmware itself.
No offsets need to be set in Slic3r.

Check the https://github.com/dob71/MarlinX2/blob/master/Marlin/Configuration.h around line 303.

For the X axis the firmware uses the extruder homing positions to assign each extruder the correct X coordinate.
This ("#define X0_MIN_POS -35") tells the firmware that extruder 0 (left one) homing position is 35mm left of the printing bed.
This ("#define X1_MAX_POS 252.45") tells firmware that the homing position of the extruder 1 (right one) is 42.45mm right of the printing bed.

For Y (since extruders can't move independently on this axis) firmware only needs to know the extruder offset (around line 352):
#define EXTRUDER_OFFSET_Y {0.0, -0.05} // (in mm) per extruder, offset of the extruder on the Y axis

You can also adjust the above values on the fly using M218 and M206 commands. Then save them in EEPROM using M500.

Title: Re: Extruder-offset and homing out of bed
Post by Ses4m. on Jul 8th, 2016, 3:16pm
oh... thx for you're fast answer ;D


on 07/08/16 at 14:38:02, Denis Bakin wrote:
Nice machine.
Thx, It's my third printer, designed and build by me, many many hours of work.^^




on 07/08/16 at 14:38:02, Denis Bakin wrote:
For the X axis the firmware uses the extruder homing positions to assign each extruder the correct X coordinate.
This ("#define X0_MIN_POS -35") tells the firmware that extruder 0 (left one) homing position is 35mm left of the printing bed.
This ("#define X1_MAX_POS 252.45") tells firmware that the homing position of the extruder 1 (right one) is 42.45mm right of the printing bed.
okay i think i understand... for my case:

Code:
#define X1_MIN_POS -35
#define X1_MAX_POS 210

#define X0_MIN_POS -35
#define X0_MAX_POS 210
is it right? possibly around line 335 is importent? MANUAL_HOME_POSITIONS




on 07/08/16 at 14:38:02, Denis Bakin wrote:
For Y (since extruders can't move independently on this axis) firmware only needs to know the extruder offset (around line 352):
#define EXTRUDER_OFFSET_Y {0.0, -0.05} // (in mm) per extruder, offset of the extruder on the Y axis
and the offset is the distance between the homed nozzels?
for my case:

Code:
#define EXTRUDER_OFFSET_X {0.0, 280.0}
#define EXTRUDER_OFFSET_Y {0.0, 5.5}

Title: Re: Extruder-offset and homing out of bed
Post by Denis Bakin on Jul 8th, 2016, 4:24pm
#define X1_MIN_POS -35
#define X0_MIN_POS -35
The above cannot be true unless your design allows both X-carriages to go all the way to the left having hotends pretty much sitting on top of each other. For my case the closes the hotends can get to each other is about 40mm, so for the extruder 1 the minimum X position it can reach is -35 + 40 = 10.

#define X1_MAX_POS 210
#define X0_MAX_POS 210
The same here. It does not look right unless your design allows both carriages to go all the way to the right so that hotends are exactly aligned on the X axis.

You do not need EXTRUDER_OFFSET_X (has to be zeroed) since for DUAL_X_DRIVE there is really no fixed extruder offset on the X axis. The firmware just moves the hotends independently. It uses X0_MIN_POS and X1_MAX_POS to determine where on X axis each extruder is positioned when homed and each extruder stays in that coordinate system after that. Your just need to set the numbers right, so that after homing if you move the extruder 0 to X==100 it would end up over exactly the same place (on X axis) where extruder 1 would end up if moved to X==100. If that is done right then X1_MAX_POS -  X0_MIN_POS == <distance_between_extruders_on_X_axis_when_homed>

You do not need to use MANUAL_HOME_POSITION defines.


Title: Re: Extruder-offset and homing out of bed
Post by Ses4m. on Jul 8th, 2016, 5:05pm

on 07/08/16 at 16:24:39, Denis Bakin wrote:
#define X1_MIN_POS -35
#define X0_MIN_POS -35
The above cannot be true unless your design allows both X-carriages to go all the way to the left having hotends pretty much sitting on top of each other. For my case the closes the hotends can get to each other is about 40mm, so for the extruder 1 the minimum X position it can reach is -35 + 40 = 10.

#define X1_MAX_POS 210
#define X0_MAX_POS 210
The same here. It does not look right unless your design allows both carriages to go all the way to the right so that hotends are exactly aligned on the X axis.

http://www.bmt.brothers-gaming.com/Sesam/bilder/dsc_0125.jpg
http://www.bmt.brothers-gaming.com/Sesam/bilder/dsc_0126.jpg
http://www.bmt.brothers-gaming.com/Sesam/bilder/dsc_0127.jpg (from 2 to 30)

each nozzle can move over the border of the opposite site of the bed 245mm (-35 to 210)

all values are rounded until now




on 07/08/16 at 16:24:39, Denis Bakin wrote:
You do not need EXTRUDER_OFFSET_X (has to be zeroed) since for DUAL_X_DRIVE there is really no fixed extruder offset on the X axis. The firmware just moves the hotends independently. It uses X0_MIN_POS and X1_MAX_POS to determine where on X axis each extruder is positioned when homed and each extruder stays in that coordinate system after that. Your just need to set the numbers right, so that after homing if you move the extruder 0 to X==100 it would end up over exactly the same place (on X axis) where extruder 1 would end up if moved to X==100. If that is done right then X1_MAX_POS - X0_MIN_POS == <distance_between_extruders_on_X_axis_when_homed>
ahh okay... i'm so fixed on the offset... its logic!

Title: Re: Extruder-offset and homing out of bed
Post by Ses4m. on Jul 8th, 2016, 5:45pm
omg!

x0-axis gives the values for both x-axis...
and x1-axis use the values from x0-axis...

i think until now x1 axis has own values, mirrored to the x0-axis...



#define X0_MIN_POS -35
#define X1_MIN_POS 0

#define X0_MAX_POS 210
#define X1_MAX_POS 245

http://www.bmt.brothers-gaming.com/Sesam/bilder/dsc_0125jjjj.jpg

now i'm right?

Title: Re: Extruder-offset and homing out of bed
Post by Denis Bakin on Jul 8th, 2016, 6:12pm
Yes, the numbers look right now.

Title: Re: Extruder-offset and homing out of bed
Post by Ses4m. on Jul 8th, 2016, 6:18pm

on 07/08/16 at 18:12:55, Denis Bakin wrote:
Yes, the numbers look right now.


thx a lot... my brain fucks up...  ;D ;D



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