I don't use any hair stacker. After I get the amount of hair on the jig, try to spread it around even and wrap it enough so it stays where I want it. Start your wraps at the eye end, and make several wraps to the hook side. I get a box of straight razors at the store and use to trim the edge in question. Don't get stingey with the blades, when they get dull, get another one out. If powder coated/baked right, damage to the jig should not happen, and even if it would, I push the wrapped hair towards the cut area anyway seeing that it is firmly wrapped, but not tight wrapped yet. If you would go crossed eyed and cut the thread, don't panic, that is why you started at the eye and worked you way to the hook end. Just cut the threads you damaged with the blade and continue on wrapping thread until covered. I use magnifying glasses I get at the dollar store, my eyes are bad lol.
It really is easier than I explained, wish I could do the video thing, but I am a guy that isn't into the high tech stuff, and still uses a "dumb" phone lol.