Prints always in the corner

Noob question: How can I make sure my prints are always centered on the hotbed? I'm using Repetier, Mendel90. Is it one of the calibration steps I am missing?

On most repraps, 0,0 is in a corner of the printbed. Most slicers, by default, center the model on 0,0. The fix depends on the slicer you use, in skeinforge you can use the multiply module to generate a 1*1 array of models centered on a given point.

In my experience Slic3r uses the center of the print bed, not 0,0. Skeinforge defaults to 0,0

In my case, Repetier is using Slic3r for slicing, and the plater shows X-0, Y=0 while the image seems to be at the center of the grid. Does that mean my generated gcode assumes 0,0 as the center? How do I confirm that?

This setting seems like it could help?

Looks like it. Set it to 100,100 and give it a go.

I prefer to fiddle with firmware and place the centre of my bed at (0,0) - it just seems like a much nicer way of doing it! It allows you to print in specific locations (to avoid damaged tape or print where your pva/sugar water coating is still nice) very easily. Just put the head where you want to print send G92 X0 Y0 and print.

a quick comment for skein forge "Skeinforge defaults to 0,0 "

it actually will center if you use multiply plug in and set number in x to 1 and number in y to 1

I just DL'd slicer and did my first test
I am testing on a CNC machine using Mach3
I will be building a dedicated 3D printer but for now, I just bolted my extruder to my CNC head

The first thing I noticed when doing the first test was that the Gcode start point was X+ 100mm and Y+ 100mm from where I had zero'd out my extruder head in Mach3
I had set my extruder right in the center of my 200 x 200 bed and zero'd it.
That's how it's done in the CNC world so I went with what I normally do when I cut material

I finally figured out that I had to set slic3r so that the center of the bed was 0,0, not 100,100

Then the Gcode and print started right where I had zero'd out Mach3 at 100,100, center of mt bed

That sounds like 2 diff solutions: 1) fixing the firmware; 2) changing the printer's behavior just before printing

I like the idea of fixing the x-y position (even Z?) and then starting your prints

Can you share more details of how you do that? I hope I don't have to fiddle with the g-code for this each time

konwiddak Wrote:
-------------------------------------------------------
> I prefer to fiddle with firmware and place the
> centre ofat (0,0) - it just seems like a
> much nicer way of doing it! It allows you to print
> in specific locations (to avoid damaged tape or
> print where your pva/sugar water coating is still
> nice) very easily. Just put the head where you
> want to print send G92 X0 Y0 and print.

In my case, I am using Mach3 on a CNC machine, so it's totally different than how you might do it on other hardware.

In Mach3 - CNC type work you always place the tool at zero position on the workspace and then zero out X Y and Z
So your Gcode should also start right at that Zero point

You don't want the Gcode to start printing 100mm,100mm away from your zero point

Just look at the Gcode file and see where the first X and Y moves start

To me it makes the most sense to leave the corner of your bed as 0,0,0 and adjust your slicing software to lay things out at the center of your bed.

Just seems more "standard" to do it that way. "-" positions are not really found in g-code unless your slicer is set up to do that.

My bed center is 100mm x 96mm for example.

Edited 2 time(s). Last edit at 03/02/2013 11:31AM by xclusive585.

I had slic3r set for center at 100mm,100mm
The first Gcode lines for X and Y were 101mm, 101mm and so my gantry left my zero spot and tried to start way far away

So when I told slic3r that my zero point was 0,0, the gode started right where I had zero'd out the extruder in Mach 3

seekerky Wrote:
-------------------------------------------------------
> That sounds like 2 diff solutions: 1) fixing the
> firmware; 2) changing the printer's behavior just
> before printing
>
> I like the idea of fixing the x-y position (even
> Z?) and then starting your prints
>
> Can you share more details of how you do that? I
> hope I don't have to fiddle with the g-code for
> this each time
>

You must change the following in firmware:

Centre point = 0,0
Xmax = Half extruder travel +ve
Xmin = Half extruder travel -ve
Ymax = Half bed travel +ve
Ymin = Half bed travel -ve
X end stop location = Half extruder travel -ve
Y end stop location = Half extruder travel -ve

Then set your slicer program so that (0,0) is your centre and put "G92 X0 Y0 Z0 E0" as a header on all gcode files so you don't have to manually do this yourself each time.

Put your nozzle wherever you want to start printing, zero z and press go!

Just be wary that movement limits are enforced relative to where you zero - if you try to print a large model in the top corner of your bed and the head moves too far it will run out of travel. This is unlikely to actually damage anything but makes a horrible noise!