Decide where you want to cut the bottle by loosening the screw and moving the cutting wheel forward for a shorter cut and backwards for a longer cut.
STEP 2: CUT A LINE 0N THE BOTTHER
This is exactly the same as making a score line when glass cutting. A light etch is all that is required. Apply only slight pressure on the bottle while rotating the bottle toward you with your hands. To assure an accurate cut, keep the bottle firmly against the backstop and keep it moving.
STEP 3: HEAT&COOL THE CUTTING LINE
Flush the etch with small hot water column and rotate the bottle at a faster pace to give a uniform temperature to the glass. Then put it into cold water and rotate. Repeat above steps for 2- 3 times or more than.Remember, don't use undue force, let the glass work itself free!
STEP 4: SMOOTH THE CUTTING LINE
To prevent chipping, rub the inside and outside edges lightly with a piece of the coarser polishing paper. Then use a small amount of powder on a flat, hard surface. Dip the edge of the glass in water and then place on the polishing surface.
-Helpful Hints & Cautions. -Brush some light machine oil on cutting wheel prior to cutting. -The lighter the etch, the better the separation. -Do not cut over labels. -The glass cutting wheel should always be at a right angle to the glass surface. -Always wear eye protection while working with glass and remove the bottle cap before cutting.