PDF editing in Affinity Designer

[JWalt]

I am trying to edit a PDF of a topographical map that I downloaded from the USGS web site. I then want to use the edited PDF in a Laser cutting software, (Lightburn) to then engrave the  the image. I need to crop the map down to the area that I want to use in my laser software. The PDF is a very large multi layered document that I have to go through and delete the layers that I do no want. I then do a vector crop and then change my document size to equal the new cropped PDF size. I then export the new PDF for importing into my laser software. 
My issue is the cropped PDF when imported into the laser software still has the entire PDF size and all of the vector lines that I do not want. Is there a way to remove all of the unwanted vector lines permanently so the the new resized PDF has only the vector lines that I want. I am asking if there is a workflow that I can use to get this result. I am new to Designer (CAD/CAM) guy so I don’t know my way around Designer very well.

 

Thanks !

[Paul Mc]

Are the extraneous curves from the deleted layers, outside the crop area or both?

[JWalt]

Yes the extraneous curves are not being cropped. The deleted layers are not a problem they are gone . but anything that is on an active layer is not being cropped. The objects (vector lines and text)are still being exported outside of the cropped area along with the area that I want.

 

Thanks  !

[Paul Mc]

Sorry, @JWalt but the Vector Crop Tool is misnamed (IMHO) it isn't a crop tool. It should probably be called a mask tool. The initial mask is the bounding rectangle of the curve. As you have probably found you can move the sides by dragging the handles but if you move them back the original curve is revealed. The only way to apply the crop of the mask is to Rasterise it and then you lose the curve and end up with a pixel layer. Clearly, this would be no use for your laser cutting requirement.

I've had a recent job where this was needed. I'm not sure if there is a better way but here's how I did it. Create four guides for the sides of the bounding rectangle, then with the node tool hover over the intersection points of any curve that crosses a guide until you see a small dot at the intersection of the curve and the guide, then left-click to create a new node on the curve. Once all the intersection points were created, go around the rectangle holding control/cmd down while hovering over the curves outside the box until the red X appears and then left clicking to delete each of the unwanted curve segments. It was a tedious job but gave me a result I could work with.

[Old Bruce]

22 hours ago, Paul Mc said:

It was a tedious job but gave me a result I could work with.

I don't know why we cannot just have a Cookie Cutter / Die Cut tool or method that would automate this. Slice through the curves at the intersection of the shape you draw or choose to use as a cookie cutter.

Hell, even a Knife tool or Scissors tool would be great for this sort of work.

[Paul Mc]

@Old Bruce the fact that I can do it manually by creating a new node at the intersections which preserves the tangents on the curves means this could be automated. I guess it is competing with other features that are on the to-do list and not considered urgent.