How to center nozzles on printbed?

[René @3dnerd]

Dear all,

is there any way to center the nozzles on the printbed before printing?
I need to center it because I want to print an object with a length of 200mm.
Since ABS shrinks I entered a scaling of 102% so the legth wil become 204 mm.
This even fits onto the printbed. But if the nozzle is not centered then it does not fit anymore.

How can I center the nozzles in X and Y direction?

[Zach @darthviper107 My Robox is a Green Kickstarter Limited Edition]

I don’t think that’s a problem you need to worry about, you can position the print in the software and if it fits then it will print, there’s nothing about centering the nozzles that you need to do.

[René @3dnerd]

Hi Zach,

this is not quite true. Currently I need a test print to check where exactly the center of the printed is.
If an object has a size of 200mm x 100mm AM will position it at 100 x 50.
But if I print it then it is not in the center of the printed. If I enter 102 for the x axis and 48,5 then it is centered.
I just thought there is some centering algorithm that can avoid those test prints.

[Clicky @clicky]

Why would it be important for the model to be printed in exact middle of the bed? I do understand size constraint - but both AM and Robox do care where head movements are and I believe won’t let you try to print something outside of work area.

If you put your model in AM, up scale it by 2%, and if it is still inside of work area AM will let you print it. You can, of course, move it around (just a bit) if you want to, but you don’t need. AM is definitively making sure that no parts of printed object is outside of work area (in this case we refer it as ‘printing bed’).

So, all you need is to place your object in AM, scale it and… Print it!

Anyway - problem of finding exact centre is not a problem you might have at all, but ability to print on almost whole surface of the PEI bed. If it is even so slightly bent, you night have issues with filament sticking near extremes and being squashed in the middle… It is good idea to observe printer printing first couple of layers.

[René @3dnerd]

Hi Clicky,

as I mentioned in my 1st post here it is a question of big objects. If I want to print lets say 210 mm and just hit print then the objects is not 210 mm!
(I don’t consider the shrinkage here). The problem is even if AM place it at X-Axis 105 mm the real print is not in the middle of the print bed x axis.
It is shifted to the left for around 1mm. That means my object will get a size of only 209mm since the printhead cannot move any further to the left because there is the limit.
(the Robox inner housing left wall). So to get it printed in the center of x axis I have to change 105mm to 106mm on x axis position. Then it came out quite well.
The printhead does not exactly know where the center of the bed is. Therefor I asked for some calibration option inside AM which could do this task in some way instead of printing a large object just for manually calibrating the center.

BTW: Even if an object turns into red inside the AM virtual printbed it can be printed! The head just moves over the printbed and prints in the air!
This I tested yesterday!

 

[Clicky @clicky]

I think I understand what you mean: AM has weird way of presenting position. I expected that position is bottom left corner of the object - and it isn’t!

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