How many screws do you need? There are enough screws provided with each bundle or assortment kit to put a screw every 3". This is more than adequate. The only forces these screws must resist is the weight of all the glass, art, & backing when the frame is picked up, face up, by just the frame. Normally, the majority of the weight (the glass) is supported by the frame. If the backing or art is extremely heavy, use another method.
After each side has been drilled, remove the Rabbetspace and all the drilling dust, fill the frame, attach the Rabbetspace. Leave each screw slightly loose to prevent buckling due to changes in temperature.
