Print Bed Area different from Machine Size

[tryptamine 3]

Dear Community,

 

When trying to max out my print bed, i realized that my printer can print next to the bed.

 

In my machine, the traves area is much larger than the bed area. 

 

In 'printer settings', i can only set the Printer size, defining the maximum travel area. 

How i can limit this to only the print bed area? I do not want to use M206, because some of my Macros (e.g. Change of Filament) require the printhead to be next to the printing bed.

I just want to add forbidden zones in Cura Slicer.

[Dustin 143]

Sounds like you have Negative Travel on your printer?

Example you can travel 10mm to the left of your bed or something like that?
It means the following
Assuming your bed was 200mm on X and the endstop is 10mm to the left of that.
It means your home position is actually X-10 not X0.

This would be a firmware setting that needs fixed, not a slicer setting/configuration.

 

[gr5 2,189]

I tend to agree with Dustin.  Can you use negative values for your macros?  Will your printer handle those okay?

 

If not you can add M92 commands to your macro.  In the above example where you want to print only X>=10 you could add:

G0 X10

M92 X0

 

M92 tells the printer where it is.  It says "I know you think you are at x=10 but really this is X=0 now".  Then on the tool change you can do something like:

G0 X0

M92 X10

 

The above says - okay were are reversing what we said before.

 

To answer your question, yes you can define forbidden zones.  I don't know how to do it exactly.  It's done for example for the UM series printers to say where the bed clips are.  The areas are described in a text file that I think is either javascript ".js" or json  ".json"?  Something like that.  They are somewhere among the thousands of files installed when you install cura.  If you edit one, then restart cura to have cura reload all of those.  There is discussion on how to set this kind of thing up for custom printer settings around this forum.  Maybe use google to search something like "customizing print area for my printer".

[GregValiant 1,287]

Hi folks.

I'm not seeing why @tryptamine can't use M206.  It's a better solution as it's essentially permanent and probably needs to be done anyway or the midpoint of the printer won't match the midpoint of the Cura build plate.

Tryptamine - can you alter your macro to tell the printer to go to something like X -10 instead of X0?

 

I use M206 when I have to mirror a gcode file or to set the printer up as an Origin at Center printer because that is how the particular gcode was sliced.  Either way there are a lot of negative X and/or Y locations.

 

Those methods both work so there isn't anything actually keeping the printer from moving to negative numbers other than than maybe convention.

@Dustin and @gr5 will need to address the UM printers as I don't know them but for those "other" printers like my Ender - M206 should be the solution provided of course that the macro can be altered to a negative location.

Edited January 3, 2023 by GregValiant

[tryptamine 3]

So as a summary, the 0 point should not be the point where all axis are at the endstop (the minimum position every axis can reach in my case) BUT at the corner of the heated bed?

[GregValiant 1,287]

Yes.  The "Auto-Home" location is just where the switches happen to be located.  It is only used by the printer so the printer knows where the print head actually is in space.  The printer sets the "Stepper Locations" of the X, Y, and Z to 0 when you Auto-Home.

 

The "Home Offset" 0,0,0 is the actual Origin point of the printer.  It is where the printer will put the "Origin" of a gcode file.  There is of course a relation between the "Home Offset" position and the "Auto-Home" location, but it is the "Home Offset" location that is important for actually positioning a gcode file on your printer's build plate.

 

I'll use my Ender 3 Pro as an example.

My glass build plate physically measures 235 x 235.  It has a 1mm beveled edge all around the periphery that can't be printed on.  My preference is to put another 1.5mm safety area all around the periphery.  So my total "non-printable" area is a 2.5mm border all the way around the glass.  That leaves me with a "Printable Area" 230 x 230 and that is what I enter into Cura as my build plate size.

After Auto-Homing the printer - my nozzle happens to be aligned with the left edge of the glass and is 2.5mm in front of the front edge of the glass.  That is a non-printable location.  I move the nozzle so it is 2.5mm in from the left edge, and 2.5mm in from the front edge, and at a Z=0 and then I use the LCD control to set the Home Offset location at that point in space and then use the LCD "Save Settings" command.  That is the normal situation.

If I then tell the printer to move to X=115 and Y=115 the nozzle will be smack dab at the mid-point of the glass.  That will align it perfectly with the Cura build plate.

 

For specialty situations the Home Offset location can be altered using an M206 command in the gcode.  G92 could also be used to change where the printer "thinks" the nozzle is.

 

Edited January 3, 2023 by GregValiant