Getting Heavy Blade Burn

[James Evers]

I'm using a Bosch cs10 circular saw with a Forrest Woodworker 7 1/4".
I'm cutting 3/4" 13-ply BirchPly sheets for a subwoofer build.

My method of setup consists of me clamping a straight edge to 1 side of the cut and clamping that same side to the workmate I have.


The problem is one side of the cut is burning and the other side is completely clean.

It's a new blade, the cut's are still very smooth and the depth is set for 1 tooth width. So I can't figure out why it's having this issue. The cut's are very clean too.
Does clamping one side of a work piece cause it to rub against a cut line producing wood burning?
Could running along a straight edge cause that?

I've heard some people wax their blades would this help prevent burning.

[Paul Atkins]

Oh, I thought this was about shaving --- Actually I think your guide is not exactly parallel with your blade. If your saw base is not exactly lined up, you will be cutting at a skew. Even a hair off will cause burning on one side. Try a scrap freehand following a pencil line and see if the base is parallel. You might have to shim it a bit or hit it with a hammer to re-align it (!)

[James Evers]

Oh, I thought this was about shaving --- Actually I think your guide is not exactly parallel with your blade. If your saw base is not exactly lined up, you will be cutting at a skew. Even a hair off will cause burning on one side. Try a scrap freehand following a pencil line and see if the base is parallel. You might have to shim it a bit or hit it with a hammer to re-align it (!)

Ahh so the base of the saw is off from the blade or the blade is off from the base. :eek:

[Lee Schierer]

The saw blade is not parallel to your edge guide. Even a few thousandths of an inch out of exactly parallel will cause burning on one side of the blade.

[glenn bradley]

As Lee and Paul say, adjustable shoe plates on circ saws are few and far between even though it seems so basic. the makers must feel that most folks are doing "rough work" so "who cares"? Tsk, tsk.

I aligned an old C-man by driving out the roll pin that held one end of the shoe and inserting shim material till I was happy. Another solution is to create a zero clearance shoe out of thin hardboard and make the edge of this accurate (obviously extending past the offending shoe).

Here's a pretty cool one: http://woodworking.phruksawan.com/zctpForCircularSaw/index.html

[James Evers]

Could I use a good router bit to cut plywood? I've heard of folks using a jigsaw as well, but I'm thinking it's not likely to be any straighter.

[Charles Krieger]

I too have experienced problems with the base plate of my circular saw not being parallel to the blade. I am going to take my Porter Cable MAG in for repair to see if they can correct it. It is off by an amount equivalent to the blade kerf and that is not acceptable. Not only does it burn one edge but it is very difficult to guide along a straight edge and the cuts are very rough. Porter Cable needs to clean up their act. I could expect this type of problem from a HF saw but not PC.:(

[glenn bradley]

Could I use a good router bit to cut plywood?

Yes. Cutting near the line with a jig or circular saw and then using a straight edge clamped to the panel as a guide and a router to dress up the cut is a common method of doing this.

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I am going to take my Porter Cable MAG in for repair to see if they can correct it. It is off by an amount equivalent to the blade kerf and that is not acceptable.

I agree, that much of an error is quite unacceptable. I had my PC Mag go odd on me. I discovered a bit of spoil had gotten between the depth adjustment "slide" / locking lever and the housing. You'll notice if you release that lever that the shoe can be moved quite a bit out of true. Be sure nothing is stuck in there. Tightening the depth lever with some sawdust in there was what was throwing my saw off. It could save you a trip to the fixit shop.

[Myk Rian]

Could I use a good router bit to cut plywood? I've heard of folks using a jigsaw as well, but I'm thinking it's not likely to be any straighter.
Use a compression bit to do a FINAL cut on the ply. I wouldn't use it to make the whole cut.

[Charles Krieger]

Thanks Glenn, for the tip. I just went out to the shop and checked my PC MAG saw and I do not have the problem you describe. My base is out of parallel to the blade by at least 1/16" from the front of the blade to the base compared to the rear of the blade to the base. It appears the height adjustment support has the right angle bend in the wrong place. (Perhaps since it is a manufacturing error PC will fix it at no cost.) In any event I will either have to get this one fixed or get a new saw even though this saw has seen only a few cuts. I am considering the Festool even though the price is a bit high for an old retired guy.