ETA, reading around found the name, "round plough", here's a better description and much better drawings than mine, I was going from several years old memory.
Old post below:
A wood plane won't work, the cutting angle's very wrong.
There is a knife specifically for trimming pages, and yes it is rather heavy, because the blade is mounted on what's really a scaled down vise. The blade is circular with an asymmetric edge which makes it able to cut flush with it's outside surface.
My father has one, so I'll post a picture once I get a chance, in the meanwhile, here's a hastily drawn Henrikdoodle of it.
Upper left is the vise, with the tiny ledge like thingie drawn in. Upper right is the knife, lower left is a schematic of the knife in action.
In practice it's used by putting the vise in your lap, book between the legs, take the opened knife and lay it on top of the vise so the part without the knife is up against the small ledge-like thingie on the vise. That way you have a perfectly repeatable parallel action back and forth, with the cutting edge of the blade flush with the surface of the vise.
The cutting is done in multiple passes, with each pull tightening the knife a bit and cutting along length of the book so a couple of pages are cut.
The point to the knife is that the cutting action itself is done by a sharp blade pulled at a very shallow angle so there's no tearing (like there would be if you tried with a plane), and that it's held fixed so controlled parallel cuts are easy.
Last edited by HenrikOlsen; 2011-Mar-20 at 05:21 PM.
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