Reply To: Is bleed required in all cases

Indeed Jongware. I was just illustrating that the paper goes through a process of being mechanically fed into machines. The registration is usually spot on, but then the paper is stacked again on the opposite end of the print machine. It's then moved, usually my a hand truck (pallette truck) to the guillotine operator who hand stacks them onto the guillotine.

And of course as you point out that the paper can slide as the knife cuts through. Which is very rare. Theres a massive clamp that holds the paper in position.

But some pages can slip and slide. And of course you can have the item trimmed on a stitching machine like a Muller.

First picture is the guillotine and second is the muller

This would be typical as you can imagine if one sheet in that stack slips by 1 mm you would get a sliver of white showing – if they didn't use bleeds

I'm not sure if this particular machine trims – I imagine it does, but this is the basic Saddle Stitching machine, where it's stapled and edges can be trimmed.