Use a specialized blade used with the saw such as mikita hardiblade or dewalts filber cement blade.
Cutting cement board siding.
I recommend the turboshear tsf1a fiber cement pnuematic if you re looking to buy a pneumatic siding shear.
To keep dust to a minimum use a circular saw that s equipped with either a dust collection bag or electric fan that.
When cutting fiber cement siding with circular saw use a blade that has only four or six teeth.
The cleanest way to cut fiber cement siding is by using siding shears.
For a slow but virtually dustless way to cut siding use power.
Typically siding shears use air pressure to power them and they shear or cut the siding like a pair of scissors.
If any cutting needs to be done to allow for the added flashing than it can be done on the workbench with a pair of siding shears zero dust.
You have to make the cuts very slowly.
Use your eyeware and ear protection.