Use the standard drill bits listed in the table to drill holes to a depth greater than or equal to the combination screw mounting depth; be careful not to taper the holes and allow chips not to fall in. After drilling, the countersinking hole should not exceed 0.4 pitch depth, because the oversized countersinking hole is not conducive to the screw-in of the combination screw.2. Tapping
Use the special tap for the combination screw marked with the specified thread specification. The length of the tapping must exceed the length of the combination screw. For the through hole, all tapping is required; the accuracy of the tapping determines the tolerance zone of the final standard internal screw hole, the user needs to Proper selection of the tapping method and lubrication, and appropriate force for blind hole tapping to prevent the tap from breaking. After tapping, the threaded holes should be cleaned, usually with a compressed air spray gun, and a long spray gun with radial holes should be used to clean the blind holes from bottom to top, or the threaded holes can be cleaned by cleaning. When the threaded hole accuracy is high, use a special combination screw bottom hole plug gauge for inspection.3. Installation
In general, the hole should be left with 0.25-0.75 turns of empty thread from the surface. When installing a small amount of combination screws and when installing a combination screw with a coarse thread of M14×2 or more, it can be installed with a "T"-shaped slot or a simple tool with a threaded head, and be careful not to apply a large axial force on the combination screw mounting handle to prevent "" clutter”. After the combination screw is installed, in order to check the accuracy level of the standard internal thread hole formed, the corresponding level plug gauge can be used for inspection.4. Remove the handle
For a combination screw with a broken groove, the mounting handle should be removed after screwing into the screw hole, and a handle removal tool is required. In the case of through holes, the mounting handle of the combination screw should be broken. Generally, use a punch to align the mounting handle, and then use a hammer of about 200g to remove it. The fine-tooth combination screw can be broken by bending the mounting handle up and down with needle-nose pliers, and then remove the broken mounting handle from the screw hole.