Cura 2.4 Z Seam Alignment - how does it work?

[Nicolinux 288]

Trying to figure out what kind of coordinates Cura expects for this feature. Started with x: 0, y: 0 and the z-seam seems to be bottom left:

The question is how does Cura interpret these values? Is x: 0, y:0 bottom left of the bounding box of the model or in relation to the build plate?

Tried different values but the z-seam position does not change:

However if I take a crazy high value, it switches to top left:

WTF!? How? Why? This does not make sense

[DaHai8 74]

Your build area is 215x215

Your cube size is 24.3x24.3

Assuming your cube is centered on the build area, then the bottom left point of the cube would be at 95.35x, 95.35y

Specifying X=0 and Y=100 puts that coordinate just 4.65mm north (Y) of the bottom left corner of your cube, but on the X axis.

I believe Cura is favoring corners for Z-Seam alignments to minimize visibility, so the lower left corner of your cube is closest.

Did you try 0x, 215y for the upper left corner? This would be the top left corner of your build area. That should put the z-seam at the top-left corner of your cube.

Also try: 95x, 120y That will place your z-seam coordinate right next to the cubes upper-left corner.

You cube is define as (from lower-left corner going clockwise):

(95.35,95.35), (95.35,119.65),(119.65,119.65),(119.65,95.35)

For more accurate z-seam placements, try these corrdinates:

95x, 95y = lower left corner.

95x, 120y = upper left corner

120x, 120y = upper right corner

120x, 95y = lower right corner

Distance = sqrt((x2-x1)^2 * (y2-y1)^2))

Cura is finding the closet point (distance) to your specified z-seam location and if your points are way far away, it can give (seemingly) inconsistent results.

Edited March 6, 2017 by Guest

[Nicolinux 288]

Thank you for the insight. I tried on round/curved objects but it is not consistent. There are no edges so maybe Cura's algorithm behaves differently. I would expected it just regards the bounding box.

[DaHai8 74]

Thank you for the insight. I tried on round/curved objects but it is not consistent. There are no edges so maybe Cura's algorithm behaves differently. I would expected it just regards the bounding box.

 

Hey, I'm just making this stuff up as I go.

That's just how I'd write it/understand it.

[changedsoul 2]

It appears there is a bug maybe in how it is implemented.

Even though the object placed on the table shows as having coordinates as XYZ (0), The Z Seam XY pos seems to be referenced from the XY(0) of the table from the lower left corner.

SO an object placed in the center of the table, if I wanted a z-seam on the Y(-) side of the part, and my table was X(250mm) Y(200mm), I need to give the mid way coordinate of my X or 125mm, and a Y coordinate of 0mm.

That way it picks a spot on the part that is closest to X125Y0, it will always be on the Y(-) side of the part.

Want it on the X(-) side? Use X0Y100

Want it on the Y(+) Side? Use X125Y200

Its not perfect on where it places it on them coordinates, but its pretty close to being straight up the side

Its based on the size of the table you have specified in your printer setup. Different size tables will need different values.

[DaHai8 74]

It appears there is a bug maybe in how it is implemented.

Nope, you've got it exactly right on how to set z-seam locations.

However, the center of the board is not XY(0,0) (unless you have a Delta Machine.

The lower left corner is 0,0 and the center of the board is X125, Y100 in your example.

The confusion is Local Coordinates v. Printer Coordinates.

Your object sits in the center of the board, which is locally (0,0), however, the Printer Coordinates put it at (125,100)

Hope this helps.

Edited May 23, 2017 by Guest

[changedsoul 2]

Your object sits in the center of the board, which is locally (0,0), however, the Printer Coordinates put it at (125,100)

Thats my point, it doesnt make sense in my head to show the object placement as XY(0) when at the center of the software table if you have to specify Printer coordinates to adjust z seam.

It would be mor logical to to have it one way or the other. Being that the software makes you use Printer coordinates, it would make more sense to show the object location in reference to the printer coordinates.

This is just me, and its my opinion, and opinions are like farts, everyones got some.