Hi Mike
Yes it is good practice not to have too much of the blade above the table, It is also best if not imperative to have several teeth engaged with the material for the main length of the cut. This stops the job falling in to the gullet between the teeth. So for thin material a large number of teeth per inch are required.
Yes the support for the top guard is a sort of riving knife. In an ideal world the riving knife is matched to the kerf cut by the saw. This stops the blade being pinched by the material and is very often the case when ripping long boards which can kick back like a very bad tempered mule. The wood can twist as the tensions in the board are released with the cutting action. Yes the riving knife should be a close to the blade as practical. More often than not the sort of kick you have experienced will be due to the blade picking up on some feather or knot in the ply that you were cutting as well as the riving knife probably being too thin. The shape of the riving knife should match the blade diameter plus say 1/8 inch clearance to 1/4 inch gap.
Can I suggest you look at the types of circular saw blade that are available for your machine. The better makes of saw blade state quite clearly what they are intended to cut. For example ply will be a medium to fine TPI blade with probably three types of teeth - right cut - both sides - then left cut in rotation ans the blade goes round.. Even if you have to restrict yourself to the cheaper blades investing in those needed for the individual materials you want to cut is a good step towards safer cutting. However pick blades that have the same kerf and match the thickness of your riving knife. The blades should all be the same diameter or you will have to adjust the knife for every blade change.
Also the material can grab the blade if the riving knife and blade are not in line and both parallel to the fence. If you want to cut on the bias for a taper use a fixed support cut to the required taper and feed this through the saw parralel with the fence. You can also use a small block with a fence extension that is long enough to accomodate the work. Most accidents are due to a slip of attention and in my experience are most often when just cutting a bit to size rather than using a hand saw but it sounds as if you are well on the way to being a safe operator.
Hope I have answered the questions.
Regards
Pat  |