Ⅰ. Installation position.

A.It is not necessary for handles installed at the middle position of the door. The correct position for handles installed should be 1.2M from ground to middle of handle which caccurated by DSM according to the average stature of Chinese, the person won't feel confertable when lift hands too high or put down hands too low to pull the door. It is humorous sometimes we see the handles in the street installed higher than head of people's position.
B. If door without frame, the length from the position of drilled hole for handles to edge of door should be 50mm-10mm, if a lock need to be installed for door with double screen, the hole for installtion of handles can be widened a little.

Ⅱ. Size of the hole

A.If hole drilled on wooden door or metal door, the diameter of it only need to be wider than screw with 2mm, eg screw of 8mm then the hole drilled with diameter of 10mm.
B.It need to be take care when drill hole on glass door, first is center distance of handles need to be correct, second is hole R should be suitable. For the protection of glass, a plastic tube around screw installed for handles, so the hole can not be smaller. There is a wrong point in the industry, they think hole can not be drilled wider smaller is better becasue in their opinion if too small can be adjusted to be wider, the fact is the glass Tempered can not be drilled anymore. Eg screw of M8 installed, lost of people request to drill 12mm which difficult to install, DSM suggest builder to drill hole of 14mm. If srew with M6, DSM suggest to drill hole with 12mm.
 

Article supplied by DSM