Cutting circles in half

How would you go about cutting this shape in half from top to bottom?
I made these using lightburn built in ellipse primitive. the size for X/Y was entered in shape properties -same values = perfect circle but when i came to slice it in half using nodes editor which i thought will guide a line and/or a box face from top to bottom but what you can see is that the nodes handles/points are not on the circle/ellipse upper and lower tangents.

what am i missing and how would you cut this shape?

What i did:

  • Added a tiny 0.2 x 0.2mm circle at the center of the shape
  • created a rectangle
  • converted to path
  • snapped one of its corners to the center
  • moved it up to include half of the shape
  • boolean the shape.

Quite cumbersome. Is there a quicker way?

I now see that i can hold the rectangle at its face center and it will snap to the center of the shape to be cut… not sure - maybe it snaps to grid instead

Draw any size box, a bit taller than your outer circle. Select the box, then your outer circle.

Click this:

Then make same width. (the 2nd last button shown above)

You should have something like this:

Now select just the rectangle, then click here: (so sizing will happen relative to that side)

Make sure the ‘Aspect Lock’ is not locked, then add /2 to the value in the ‘Width’ box and hit enter.


Honestly, drawing the box from the middle, then dragging it up and using the booleans is probably about the same.

Any time you use boolean tools, the shape has to be converted from its original form into small line segments for the boolean engine, and then arcs are recovered from the result. If you did any boolean operation to the original shapes, that’s likely why the points weren’t at ‘nice’ positions.

Nope, it will snap to the circle center point, or any object center if you see a X with a little hole in the middle.

Maybe with a complete circle it would but mine has these handles on both sides. it snaps but one can’t tell if it snaps to shape center or to the grid. when i move the rectangle it snaps to each next grid cross

So I did. that explains it.

So is there a simple way to draw a line vertical or horizontal off the centre of the circle? I want to make a pie chart so I just need one line to pattern around using the circle. It needs to be from the centre otherwise once patterned they dont meet in the middle? Is the method above basically the only way? I was hoping there was a hot key to make the end of the line snap to the centre of the circle and also a hotkey to ensure when you draw the line from the centre it is vertical and doesnt snap to the nearest grid. What grid snap distance do people use? Is big like 10mm or 0.5mm better? Thanks

I am guessing the snip tool when added will do exactly this


Oz, now when i export my work as either DXF or SVG the exported file looks to be messed up.
i imported my project as either dxf or svg to deepnest and got the attached outcome. so i re-imported the exported files from LB back to LB and i see the same mess. why is that?

Lightburn exported project as either SVG or DXF

On the left is my work <<<<<<<<<<<<>>>>>>>>>>On the right is the exported file imported back to LB

I am guessing this is the same old ellipses issue… what are my options now? is there a workaround for this with current 0.9.11?

Import back into InkScape and save it again.

Any tool, including the line tool, will show you the center-snap cursor when you are at the center of a shape.




Lightburn Oz yep I see the light now… Thankyou. I was not seeing the cursor changes…

I like this type of conversation, they are interesting and rewarding. I would like to have them gathered somewhere where everyone can easily find the items again. Maybe in tips and tricks with an appropriate headline?

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I’m already doing this:

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