which better to cut interlock floors . jigsaw or circular saw?
jigsaw face up with a down-cutting blade is the safest of the two
Circular saw with a laminate cutting blade or a plywood cutting blade. It has lots of very small and very sharp teeth.
I've used both, just make sure the teeth of the saw is coming into the finished edge. If you use a circular saw a paneling blade may work best, but I had good luck with a 40 tooth carbide tipped blade.
You can use either as long as you use a blade with the proper amount of teeth. The more teeth, the finer the cut. A jigsaw blade will always be finer than any circular saw available. The jigsaw is lighter and more maneuverable but the heavier circular saw has more cutting power and the larger blade will cut through the laminate much quicker than the jigsaw. I recommend you use a cutting guage so your cuts will be straight. In either case, make sure you place the laminate with the back side up when cutting it since the blades on both machines cut on the up-stroke and the exit side of the cut will have splinters and you want this to be on the bottom of the laminate. I personally prefer a circular saw to a jigsaw for anything other than cutting curves or circles but it does require more control.
I'd strongly recommend you beg/borrow/rent a power miter saw (aka a chop saw). You can get an acceptable quality of cut with either a circular saw or a jigsaw, using the right blade. But you'll spend 4 times as long ensuring your cut is lined up and square, as compared to using a miter saw. If you do use the jigsaw or circular saw, use a fine or plywood blade. If you use a circular saw, make yourself a cutting jig. Use a 2'x2' piece of MDF or plywood to make a table top. Attach two strips of plywood across the table top, slightly wider than your flooring planks, creating a trough for the plank to sit in. About 5 in from one end, attach additional scraps of plywood on either side of the trough to create a deck to run the saw across. Finally, attach another strip of plywood across the trough to create a cutting guide for the saw. It's important that this guide be square to the trough - use a framing square if you have one to align the guide -- if you don't have a square, the factory corner on a sheet of plywood will be pretty close to square. This jig will allow you to accurate cuts fairly quickly using your circular saw. A circular saw blade spins such that the teeth are cutting up from the bottom of the board, which can leave a ragged, chipped edge when cutting laminate. If you find your laminate is chipping a lot, cut the boards face down. For cutouts around corners, doorways, etc, the jigsaw will be your best tool. Finally, have spare blades on hand. Laminate flooring (as well as most pre-finished wood floorings) have aluminum oxide in the top coat for wear resistance. Aluminum oxide is a tough abrasive that will quickly dull a saw blade.
