WORD OF CAUTION: Please be aware some extra consideration should be taken on the depth of the holes to be drilled. For example the depth for a Gibson SG has to be figured from how high the bridge is going to be above the body. If the end user were to drill the full depth of the stud they would drill all the way through the body. The stud does not need to go in that deep on SG's or Les Paul's because the neck pitch keeps the bridge a good distance above the body. When a bridge is sunk into a body (with a preferred minimum body thickness of 13/4" thick) the drilling depths would be figured from the top of the recess route at the location the studs are going to be located and the zero action of the guitar. The end user has to use common sense and good judgment on hole depths to be drilled. This is not an operation for an amateur to attempt. If the user has never installed a Floyd from scratch, and does not have a natural ability for mechanical workings, they should pay someone qualified to do this operation.
Aside from those precautions the holes depth and diameters are as follows:
The depths are related to the top of the body for a flat top solid body type guitar with a zero action of .585" and a body thickness of at least an inch and a half (1.5"). The deep drill is .169" diameter (know as a # 18 drill or 4.3 mm drill). The depth to drill the hole from the tip of the drill to the top of the body reference point is 1.4" or 35.6 mm deep. The counter bored hole centered over the last hole described is .268” diameter (known as an "I" letter drill or 7.0 mm drill). The depth of the counter bore figured from the same reference point as the deep hole is .3" deep or 7.6 mm deep. These holes need to be drilled with a drill press or a mill. The holes have to be drilled in straight and precise. The studs need to be carefully installed when first threaded into the wood to go in as straight as possible. We also recommend putting some wax on the threads of the stud to aid in cutting the threads smoothly into the wood. This can also help prevent cracking the body in this area. We would recommend using brad point drills if using a drill press. When using brad point drills you would drill the counter bore first, then drill the deep hole after the counter bored hole.