Originally Posted by kkm
To enlarge a standard grommet hole if it's not a tieoff and I want to tie off on it, or to enlarge a grommet hole to avoid it being blocked, I use an awl.
But for shared holes it's not really necessary to enlarge them since they're already large enough to accommodate two strings, and it would be difficult to enlarge them anyway unless one had a very large awl.
The scrap string is to keep a specific (upper or lower) section/channel of a shared hole open, so a string can be run from the top of one shared hole to the top of the next shared hole, or the bottom of one shared hole to the bottom of the next shared hole, and not the top of one shared hole to the bottom of the next shared hole, or the bottom of one shared hole to the top of the next shared hole, which would eventually result in a crossover, since once a string going through a shared hole is tensioned, it is virtually impossible to shift its position within the shared hole without going back and undoing at least some of the work you've done.
virgin grommets can be tight and depending on the gauge of string, i've had to use an awl to stretch the opening just enough to accomodate 2 strings before. with some stiff poly string, it might not be necessary because i can cut the string an angle making the end a needle point.