The goal for this jig was to build a jig that was portable and accurate in making crosscuts with a circular saw, and at the same time, if it could prevent or somehow collect dust, that would be nice as well. All three were accomplished but the dust collection remains tenuous as a value, but I did reduce the volumes somewhat. What I really liked is just how portable and useful this jig is, it worked better than I expected, giving extremely accurate cuts, it's light to carry around and for anyone who is looking for very nice crosscut mechanism for their circular saw, this could be the one to try. Circular saws are not universal in their designs, so a jig or sled like this could well be different for different saws, the dimensions I am giving are only guidelines.

*** UPDATE *** Many thanks to Larry Chrisman for providing both a SketchUp file and PDF file found at the highlighted links, or by going to Plans on this site.

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I made mine from scrap woods I had around the workshop and even then, it didn't take much of that. I didn't have any plans to start with except the size of the circular saw blade and the dimensions of the saw it'self, and with that, I started and here is my methodology. 
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I started off by making the sliders for the circular saw base to slide on, I made the base of these from  1/9th plywood, 2 inches wide and 22 inches long. I glued the second piece made from 1/4 inch plywood and 1-1/4 " wide and the same length. You need to make these pieces first of all so that you can see how deep the remainder of your jig carcass needs to be. 

Circular Saw Cross Cut Sled

The next piece to make was the backer board that fits inside the jig and is an "L" shaped piece of wood. The dimensions of this are not critical as whatever you make yours, will help determine the size of the carcass of your finished jig. The bottom of mine is 1/2 " and the rest of the cutaway is 3/4" so there is ample support for the wood being cut. This piece is not cut to length until near assemble stage. 

After the sliders are dry you can do a saw mock-up by place the base of the saw against one slider and the base of the "L" back near the bottom of the blade to the point where the blade would just graze the wood. This will ensure that when you are cutting wood the blade will cut all the way through. This dimension should be around 2-1/4"

Now that you have those dimensions, you can go about making the rest of the carcass of your box. Drop you saw between the 2 sliders and that will give you the width of your box. Mine turned out to be 9-1/4"

The height of the carcass can now be determined, mine worked out to be 2-3/4" not including the base of the jig which I also used 1/8" plywood for.

The final dimension is how long to make the jig, and that really depends on what you think you might be cutting, my carcass is 15" long and the "L" backer is fastened 4" from the inside of the front the riser on the "L" backer (the place where wood will abut when cutting. 

Cross Cut Jig

For assembly I used glue, screws and my air nailer, but what I did first was to coat all the edge grain surfaces with glue and let them sit for 15 minuted, I then went back and did the final assembly by re-gluing all those pieces that had been pre-coated and all the other surfaces as well. I used my 18 gauge nailer and short pins to keep all the components together while they dried.

The top sliders were mounted with washer-type screws.

Testing and using this jig was a real joy, I fell in love with it instantly. I worked great, easy to use accurate ... and yes it even does collect about half the sawdust so even that was a modicum of success, an easy weekend build and a great way to make an accurate jig that can give our circular saw even more use in the future.

Copyright - Colin Knecht

Circular Saw Cross Cut Jig