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DaHai8

Cura 2.1.1 Print Bed Size & Offset

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My printer's home position is at -40x and -40y mm from 0,0 on the platform.

I thought this parameter would allow me to set that:

machine_platform_offset

But it doesn't change anything about where the print starts printing.

Anyone know which json parameter to set for the nozzle home position relative to the 0,0 print bed home?

THanks!

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machine_platform_offset <- This is only a visual change. It defines how the 3d model of the platform needs to be moved.

There is no setting for the home position to the bed, as we had to make a cut somewhere who does what. We decided to let the printer decide what is on the platform and what isn't (eg; 0,0 must be on the platform).

The problem with having two parties being able to decide that is that it's hard to know what exactly happens (as all of the sudden both can define it and could define different values)

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machine_platform_offset <- This is only a visual change. It defines how the 3d model of the platform needs to be moved.

There is no setting for the home position to the bed, as we had to make a cut somewhere who does what. We decided to let the printer decide what is on the platform and what isn't (eg; 0,0 must be on the platform).

The problem with having two parties being able to decide that is that it's hard to know what exactly happens (as all of the sudden both can define it and could define different values)

 

So I guess that even with changin the G28 instruction it couldn't work.

The solution would be to try to change any value right on the printer ?

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It could. If you change all G28 commands to:

 

G28G0 X[offset_x] Y[offset_y] Z[offset_z]G92 X0 Y0 Z0

 

or

 

G28G92 X-[offset_x] Y-[offset_y] Z-[offset_z]

 

You'd have to check which of those works for you.

Edited by Guest

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It could. If you change all G28 commands to:

 

G28G0 X[offset_x] Y[offset_y] Z[offset_z]G92 X0 Y0 Z0

 

or

 

G28G92 X-[offset_x] Y-[offset_y] Z-[offset_z]

 

You'd have to check which of those works for you.

 

It's for @DaHai8 but I just wanted to check if my idea sounds good (:

Let's wait for his reply !

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Not sure I understand what you are proposing. But I do appreciate the help!

Sorry. I think my previous description was not very good.

When the print head is homed, it goes to X0 Y0 Z0. This is off the print bed by about 40mm to the left and 40mm in front.  The first printable position would therefore be at X40 Y40 Z0. The max print position on the print bed would be at X220 Y220 Z0. This makes the center position of the print bed at X130 Y130 Z0.

In other words, the print area is X40 Y40 Z0 to X220 Y220 Z0 and home is at X0 Y0 Z0.

So I need to be able to tell Cura that my print area starts at 40,40,0 and extends to 220,220,0 and that the center is at 130,130,0 so that 'center object' actually puts it in the middle of the print area and not the middle of the whole area starting at 0,0,0.

I think that's clearer. And looking at the G92 code, I think I'm getting what you are saying. In the start g-code, set:

 

G28 ; Goto 0,0,0G92 X-40 Y-40 Z0 ; Set this coordinate to -40,-40,0

 

Now when the printer is told to move to 0,0,0 (G1 X0 Y0 Z0)  it actually moves to X40, Y40, Z0 (which is the first printable position on the print bed.

I think I finally understand. That is SLICK!

I will try it and get back to you both!!!

Edited by Guest

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OK! It worked!

I first tried the second G92 suggestion using negative coordinates to get the Homed Position to -40,-32, 0. But my printer did like that too much. The next move command (like G1 Z15.0) caused it to want to move the print head to 0,0,15, which ran it into the bed leveling screws. It just would not keep the print head in a negative number area. Even putting the G92 after the G1 Z15.0 caused more wierdness: Moves were divided by 10, so 2cm move only went 2mm. Very strange.

The first idea, and more complex one, worked great:

 

G21        ;metric valuesG90        ;absolute positioningM82        ;set extruder to absolute modeM107       ;start with the fan offG28 X0 Y0  ;move X/Y to min endstopsG28 Z0     ;move Z to min endstopsG1 Z15.0 F{travel_speed} ;move the platform down 15mmG1 X40 Y32              ; Move to print originG92 X0 Y0 Z15.0         ; Set this coordinate to 0,0,15G92 E0                  ;zero the extruded lengthG1 F200 E3              ;extrude 3mm of feed stockG92 E0                  ;zero the extruded length againG1 F{travel_speed};Put printing message on LCD screenM117 Printing...

 

I moved the head up to avoid the bed leveling screws, then moved it in to 40,32 and then told it that was its new 0,0,15 position. Then setting the width and depth to 180mm, my prints printed right in the middle of the bed!!!

I'm SOOOOO HAPPY!!!

Thanks 00D00B and nallath!!!!!

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