Things You'll Need
Circular saw or table saw
Carbide-tipped 80-tooth blade
Billy shelves have a veneered edge on the front, but not on the sides or back. If you rip the shelf to make it narrower, make sure the off-cut is from the back of the shelf so you can preserve the veneered edge. If you prefer, you can purchase edge beading and apply it to all the edges after you're finished cutting.
Wear safety glasses when cutting the shelf to protect your eyes from flying shards of wood and plastic.
The Ikea Billy, a freestanding bookcase, comes in white, brown, black and birch veneer and in two standard heights. The top, bottom, sides and shelves are constructed of particleboard covered with wood veneer or plastic. The shelves are designed to fit the bookshelf, but because they are made from particleboard, it's possible to cut them if you need adapt them for another purpose. You can do this with a circular saw, table saw or jigsaw, but you need to use a special blade and cutting procedure if you want to avoid chipping the veneer or plastic coating.
Equip your circular saw with a carbide-tipped blade that has 80 or more teeth to make a crosscut or rip cut. You can also make these cuts with a table saw after first installing a similar blade. To make curved cuts, use a jigsaw with a metal-cutting blade.
Mark the cut line on the back of the shelf -- the side that will be least visible -- when cutting with a circular saw. Cut from that side of the shelf. When cutting with a table saw, push the shelf through with its best side facing up. These strategies minimize chipping on the good side of the shelf.
Support the shelf on a workbench with the off-cut hanging over the edge to cut it with a circular saw. Hold it firmly -- clamping it to the bench, if necessary. Set the cutting depth of the saw to 1/4 inch and make a preliminary cut. When this is complete, set the depth to cut all the way through and make a second cut. When you're finished, bot sides of the shelf should be chip-free.
Employ a similar technique when cutting with a table saw. Set the blade height to 1/4 inch and make the first pass, then set the blade height to about 1/2 inch more than the thickness of the shelf and make the second cut.
Minimize chipping when cutting curves by laying masking tape on the shelf and drawing the cut line on the tape with a pencil. Cut through the tape with a jigsaw. Don't turn the shelf over and cut from the back when cutting curves; that makes taking measurements and drawing lines more difficult.
Chris Deziel is a contractor, builder and general fix-it pro who has been active in the construction trades for 40 years. He has degrees in science and humanities and years of teaching experience. An avid craftsman and musician, Deziel began writing on home improvement topics in 2010. He worked as an expert consultant with eHow Now and Pro Referral -- a Home Depot site. A DIYer by nature, Deziel regularly shares tips and tricks for a better home and garden at Hunker.com.