I have a few marking tools from Incra and Woodpeckers that have precision holes for use when marking with their mechanical pencils.
I have both the woodpecker and Incra mechanical pencils, but the lead in these seems so fragile.
If I get enough lead exposed that it will contact the wood, through the square or ruler, the lead is so fragile it just breaks.
If I just support the pencil, with no downward pressure, as I try to mark, I either break the lead or it doesn't leave a pencil mark.
What am I doing wrong or if there a better lead or pencil.