To print a Skalp section as intended with sharp lines, its scale,set on the Skalp dialog, must match the Print Scale setting in SketchUp. Access and set the Sketchup Print Scale from the ‘File > Document Setup…’ panel. You may need to uncheck ‘Fit View to Page’.
Printing in SketchUp will print either your active screen view or what you have stored in your scene if you print a range of pages at once.
When a Print scale is set, zooming will influence the paper size needed to fit your content.