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How To Make a Long Circular Saw Guide

A Must-Have Tool for Making Long, Straight Cuts on Plywood and MDF

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A long circular saw guide.

A circular saw guide ready for use.

Jeff Beneke

Homemade circular saw guides are easy to assemble, and they allow you to make straight, square cuts without needing a table saw. If you need to cut boards or other relatively short pieces of plywood or MDF, see these instructions for making a short saw guide. But when cutting the full 8-ft. length of wood-based sheet goods, a longer saw guide is required.

This circular saw guide is even easier to build than its shorter cousin, as it is composed of two, rather than three, pieces. Once assembled, the saw guide allows you to measure and mark for the cut, clamp on the guide and make a cut much straighter than you could make freehand—and much more safely than if using a table saw.

What you will need:

  • For the fence, an 8-ft.-long 1x4, which needs to have one very straight edge. Don’t be afraid to set some boards on the floor at your lumberyard or some other flat surface and see if any light shines through the bottom. If it does, look for a straighter edge
  • For the base, an 8-ft.-long by 12-in. (minimum) strip of 1/4-in. or 1/2-in. plywood or MDF
  • Wood glue
  • Small screws, nails or brads, shorter in length than the combined thickness of your base and fence

What to do:

  1. Position the 1x4 about 1 1/2 in. away from one edge of the plywood, making sure the edges of the two pieces are parallel. Fasten the plywood to the 1x4 using wood glue and nails, screws or brads driven every 8 to 10 in. Drive fasteners through the plywood first (it's usually best to nail through the thinner piece into the thicker piece).
  2. Set the saw on the base, with the side of the saw's shoe against the 1x4. Cut the excess plywood along its full length.

How to use it:

First, familiarize yourself with these tips on using a circular saw. Then, when you need to cut a long board or sheet, just measure and mark the piece to be cut on both ends. Now align your cut marks with the edge of the guide, clamp the guide on each end, as shown in the photograph, and cut.

Let the shoe (or base) of your circular saw slide along the edge of the fence. The blade will, in turn, cut right along the edge of the base of the saw guide. It's quick, safe and a whole lot cheaper than buying a table saw.

Related Video
Cut With a Circular Saw
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