The Cold Saw's rotating blade is a hazard. The Blade Guard is necessary to protect others from the blade, especially during rotation.
Conventionally, the blade guard is comprised of 2 thin semi-circular discs that are attached by a thin flat bar that spans about half the circumference of the blade. This is the design selected for its ease of manufacturing (torch a thin sheet of metal using a circle cutter, then torch the circle in half; tack weld the half-circles to a long thin flat bar then fully weld them together).
What holds the blade guard to the Cold Saw: 2 bent flat bars welded to the blade guard and fastened to the Cold Saw.
The blade guard itself should be made of thin metal for lightweight holding to the Cold Saw, between 1 and 2mm thick.
The flat bar that spans some of the blade's circumference is here named the "Guard Flat". For a 350mm diameter blade, let's use a guard diameter of 400mm. Half the length of the guard circumference is:
Diameter * pi * Amount of Circumference = Length of Guard Flat
400mm * pi * 0.5 = 630mm (approx)
The half-circle pieces that cover the blade on either side are here named the "Guard Side". The Guard Side has an outer diameter of 400mm to match the guard diameter, and an inner diameter of 150mm for ease of access to the rotation assembly.
The Guard Side is 70mm wide to accommodate ease of replacing the blade.
The blade guard support should be made of thicker metal for rigidly holding the actual blade guard to the Cold Saw.
The blade guard support is made of 2 flat bars of 25.4mm width that are each bent twice and mounted to the same fasteners used to mount the hydraulic motor.
The blade guard support flat bars are here named the "Guard Support". Thickness for rigidity while allowing ease of bending is 3mm.
Each Guard Support has 2 mounting holes of 12mm diameter (to fit M12x1.75 screws) starting 20mm from the end of the flat bar and spaced 40mm apart (same as 1 mounting dimension of the hydraulic motor).
In reference to the same end datum edge, Each Guard Support has the first bend at 80mm, the second bend at 130mm (leaving 20mm space away from the closest blade face), ending at 240mm.
The Guard Supports are welded to the Guard Sides, and the Guard Sides are welded to the Guard Flat.