X, Y, Co-ordinate problems

Hello :-)

I'm having some problems with work and extruder positions on the print bed - also a possible related Z probe position issue that may be related but I'll try and get the initial positions sorted first!

Usable print bed area is 850mm (X) by 600mm (Y).

Two extruder setup, second extruder is 134mm behind the first on the X plane.

The extruder offset is set in the firmware and set to zero in sli3cr. Printing a part with either extruder results and the same printing position so the offset would seem to be working ok.

The first issue is that when extruder 2 is selected the gantry moves forward after homing 134mm to place extruder 2 in the same position as number 1 correctly applying the offset. However it is still possible to command a full 850mm X positive move resulting in a X axis end crash.

The second issue is positioning the work on the bed prior to slicing. Using the "center object" command results in the object printing correctly in the center of the bed using either extruder but according to the host seems to be at a completely random location in regards to the X,Y distance - see screen shot.

Centre of the bed should be, X = 425mm, Y = 300mm. However in the host the center shows as, X = 130mm, Y = 337mm.

I'd be grateful if anyone can show me where I've set this up wrong!

image

     


Comments

  • Posts: 19

    Further to the above - it seems the post didn't like my screen shot!

    Printer settings in Repetier Host are as follows:

    X min: 0, X max: 850, Bed left:0,

    Y min: 0, Y max: 500, Bed front -15

    Print area,

    Width: 850

    Depth:600


  • Your real width it 850-134mm. Only that area can be touched by both extruders without reaching right end!

    With host position, there is a fat dot on the bed marking 0,0. Apart from this I can not see the error from your values, and without the pictures I seem to miss the error.
  • Posts: 19
    Thank you for the reply. I'll reduce the bed size down to reflect the area usable for both extruded and see what effect that has.

    The positioning error seems to be in the host in that if I place an object on the bed using the center command on the tool bar it prints correctly in the center of the bed and the start position coordinates are correct on the LCD display but the position according to the host prior to slicing has no resemblance to actual print coordinates.

    Problem arises as the print area is formed of multiple heated beds and ideally when printing a small part I would like to place it in the middle of a single heat pad and disable the rest.

    I'll let you know if setting the new "two extruder" bed size fixes the problem,

    Thanks again
  • What you see are coordinates send to firmware. Not sure how you select the bed part and how that influences positions. Might there be a relation?
  • Posts: 19

    Hi Repetier,

    Thanks for your replies above. Its taken a little longer than anticipated to sort out a few other bits!

    I've adjusted the print area to reflect that available to both extruders and machine is working perfectly remaining within the print area with both extruders.

    My problem seems to still exist in the Host with positioning the work within the print area. I've imported 7 different objects (separately) and centred them using the host "centre object" command under the object placement tab. Each one once centred, though correct visually when looking plan view has vastly differing "X,Y (and often Z) co-ordinates. Some times the centred co-ordinates of the object are actually out side of the print area.

    Once sliced and under the "print preview" tab there is also a shift from the middle of the bed to the actual print position.

    The print bed of my printer is physically mapped out in X and Y and I'm looking to set the actual print position rather than always being where the host decides.

    I hope this describes the problem ok - will try and add some screen shots below this post to truly illustrate.

    Cheers,

          

  • Posts: 19

    Sorry it doesn't seem possible to paste the screenshot so will try and list out what I'm seeing below.

    Host Settings:

    X min 0 X Max 700

    Y min 0 Y Max 500

    Print Width 700

    Print Depth 500

    Print Height 257


    Slic3r Settings: X = 700, Y= 500.

    When centred in the Host the object shows correctly in the centre of the bed however the position given by its co-ordinates are: X = 855.25, Y = 406.25, Z = 9.00001 (this is outside the print area!)

    Once sliced the object moves across the bed towards the X positive end. The first print co-ordinate in the generated g-code is X318.622, Y219.487 

    Whilst this isn't too far off the centre of the print area, it bears no resemblance to the initial placement co-ordinates or the print preview!


    Also is it possible to upload a screenshot on the forum?

         



  • Posts: 0
    To upload screenshots they must be on some other server and you the only post the link.

    Do you have set extruder offsets in host and slicer to 0 since firmware does handle this? If not it might change display/position by that offset.
  • Posts: 19

    Removing the offsets has helped. The print is now in the same position as the slicing which is a great start!

    My issue is still remaining with the positioning co-ordinates. In the host once an object is imported clicking on the "move object" icon, brings up the objects position with its co-ordinates. It is these that differ each time I import and centre an object sometimes with the values being outside the print area (X max = 700 when centred objects X position = 2593.42).  

  • Posts: 0
    These coordinates can fool you. It is the origin of the imported stl i your coordinate system. So this depends on how and where the designer has drawn the object. It has no direct relation to the position the stl has on bed except that changing it by 1mm moves it 1mm.
  • Posts: 19

    Thanks Repetier, yes it seems that's the problem. Just been back and modelled tests with an origin of zero, zero in the CAD drawing and the co-ordinates are indeed carried over to Repetier Host when importing.

    Is there anyway around this? It seems slightly perverse to carry the position data over when it has no resemblance to the Host.

    I'm looking to position objects on the print bed using co-ordinates rather than just always using the centre.    

  • Posts: 0
    It is quite essential to keep this origin stored if you have multi-colored objects so the offsets get not destroyed on import. So no, there is no real way around, also if you hit the gear next to filename you see size and minimum/maximum coordinate on bed. From this you could compute the delta, but honestly - you normally just do position by sight hitting right mouse button and drag the object. I mean you must hit the bed everything else is not that important.
  • Posts: 19
    Ok thanks again :-)
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