I have an old Penn Jigmaster and a broomstick with reel seats either end. I wind my braid from the spool onto my grinder first in order to gauge how much will fit. I cut it off when the spool is looking a little overfilled then wind it all off the grinder and onto the Penn. I then wind back onto the grinder using the Penn's drag to create the necessary tension. With the braid under tension, the grinder usually comes out correctly filled... a mm or 2 below the lip.