# How to make a long shallow cut on a narrow piece of wood with a circular saw

I am using 5.5 inch wide cedar fence board as lapboard style siding on a chicken coop. The roof is a ~22 degrees shed style roof. I'm having trouble making the long cuts which touch the roof. The one cut I made in the picture below was much more difficult than I wanted it to be. I do not own a table saw or a sliding miter saw. I do have available a circular saw (which I used for this one cut) and a miter saw with a 10 inch blade.

What is the best strategy for making such a long cut?

You need a guide board. Figure out the distance from the edge of the circular saw blade to the edge of the plate, preferably not the side that the motor hangs over, or your board will have to be very thin to fit underneath it. Clamp the board (make sure it's a straight one!) to the work piece parallel to the cut line, at the distance you measured on your circular saw. Run the plate of the saw along the guide board as you cut, and your cut will follow your cut line exactly. I did this for a long time back before I got a table saw, and still do it when cutting large stock like plywood sheets that can't easily be cut on the table saw.

• Typically I know that I need to place my guide board 1-3/8 inches from the cut line for it to be accurate. I guess I need to do the math to figure out how far that is when stretched by the 22 degree angle. I was having a hard time just sort of "lining it up". I'll try this.
Commented Mar 19, 2015 at 14:56
• Thinking about it now too, I should probably make this diagonal cut, hoping to get the angle right, then make the 90 degree cut to make the length right because cutting the length first means I can have 0 error on the more difficult cut.
Commented Mar 19, 2015 at 14:58
• That sounds like a great idea! The 90 will be much easier to make perfect. Commented Mar 20, 2015 at 13:51

As Drew said you can use a guide board.

However, when using a circular saw myself, I just draw the straight line I need to cut and then make sure the piece that needs to be cut is secured (often a partner holding it down but a simple clamp or two can work too). Of course the board will be flat (like a piece of plywood sitting on saw horses) to the ground. Cutting along the line is pretty easy, there is a mark on the front guide that shows you where the blade cuts, keep it on the line. Just don't push the saw faster than it wants to cut.

A bonus, when you are getting short boards like that, you can get 2 pieces with one cut! the second board just need to be cut to length square!

Don't bother measuring distance between edge of saw plate and blade. Make your own guide rail instead.

Get a piece of something flat (plywood, hardboard (i have used a 5mm sheet of plastic and second time a piece of diy floor board)) and glue/screw something straight on to it. Place your saw against the Straight edge and saw away. Now the Flat will be cut exactly where the blade is. Finally clamp your home made guide rail to the board you want to cut and saw away.

• This is what I do for cutting those long straight cuts, but the home made saw guide isn't as easy to use for making mitered cuts unless you make a custom one for the particular angle you're cutting. Commented Jul 21, 2015 at 20:10