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Episode 34 – Cutting and Sawing Part 3

This episode talks about fixtures and setups to do highly accurate cuts with a portable circuilar saw.   The same information as contained on this blog is also available in a pdf fileCutting and Sawing Part 3 Notes.

The first thing discussed is the necessity to try to support the piece of wood being cut. This must be done because once only a thin piece of wood is left ahead of the saw kerf, the weight of the piece being cut will cause the wood to split and create tear in the work piece. Normally this is accomplished using a helper to hold the piece being cut off. However, I usually have to work alone, so I want some kind of support.

I use a picnic table to support the work piece. That creates a problem because I don’t want to cut into the table. The fix for that is to use 4 pieces of 2X4 as spacers and supports. I use 2 to support the remaining piece of wood and 2 to support the piece being cut-off. This means I have about 1 ½ inch of space from the work piece to the top of the table. Depth adjustment is very important to keep from cutting into the table top.

Next I discuss the use of the rip fence on the saw. The first thing to notice is that the blade side of the shoe on the saw is not lined up with the blade. This space has to be accounted for while using the shoe edge as a reference. I have to make a correction to the audio. This particular saw has marking on the rip fence scale in 1/8” increments, much better than what I thought. This rip fence can also be moved to below the saw shoe so zero does not have to reference the shoe. This particular saw is much better than the ones I have used in the past!

Picture 1: Blade to shoe distance.

Picture 2: The rip fence attachment.

Once the rip fence is set-up, The saw is held against the material and the cut will be uniform to the edge of the material. As always, test the adjustment on scrap material before making the cut on the actual board.

The next picture shows the problem with using the motor side of the shoe. If the saw is set to cut a deep depth cut, the saw motor is so close to the shoe there is very little space to use any kind of guide or clamps for the guide.

Picture 3. Clearance between the work piece and the saw motor with a deep cut setting.

The one tool that can be used on the motor side is a speed square held by hand. This will permit the ability to produce fast cuts that are square across the board. The position of the saw is set by sight by aligning the blade with the line marked on the board. The speed square is simply used to make sure the cut is square.

Picture 4: A speed square. – Note an adjustable combination square would also work.

The next fixture is useful to make accurate cuts across or along a 4X8 ft piece of plywood or other sheet material. Many years ago I built something using this principle by simply cutting off a section some of the sheet material and using the factory cut edge as my straight edge. However, about 3 or 4 years ago I purchased the guide shown in the following pictures. It is very handy because it breaks into 2 pieces, each of which is a little over 4 ft long. However it also has a very snug splice plate that joins the two pieces to create an 8 ft straight edge. It is thin so it is easy to clamp to the work piece.

Picture 5: The straight edge tool for making highly accurate cuts with a circular saw.

Picture 6: A close-up of the splice plate for the straight-edge fixture.

The straight edge is used as a guide to the saw on the blade side of the saw shoe. It is necessary to compensate for the blade to saw shoe distance and this is most easily done by cutting a spacer of exactly that distance. The cutting of this spacer is done by using a scrap piece of material and butting both it and the saw up against the same straight edge. Then the cutting edge guide can be clamped to the work piece after setting placing the spacer on the mark made when measuring the work piece and then placing the cutting guide next to this spacer.

Picture 7: Setting up the guide by using a spacer as described above. Note this is being done on the back side of cut, the side where the cut will be finished.

The final picture shows a partial cut using the guide. Please note the accurate piece is the piece to the right of this picture. The spacer we used did not compensate for the saw kerf.

Picture 8: The saw was stopped mid-cut to show the actual guide in use and the saw kerf.

In the audio I describe how spacers can be used so the final picture shows a partial cut using the guide. Please note the accurate piece is the piece to the right of this picture. The spacer we used did not compensate for the saw kerf.he final picture shows a partial cut using the guide. Please note the accurate piece is the piece to the right of this picture. The spacer we used did not compensate for the saw kerf.cutting guide can be made to bridge over the material. Once that is done the cutting guide can be clamped to the table and a stop also clamped to the table and repeating cuts can be made to cut several pieces of material all at exactly the same size.


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