1. Grinding the drill bit is the beginning
Before drilling, the corresponding drill bit should be selected for sharpening. In addition to maintaining the correct top angle, relief angle, and chisel edge bevel, the sharpening drill bit is equal, the length of the two main cutting edges is flat and symmetrical with the center line of the drill, and the two main flanks are smooth, in order to facilitate the centering and reduce the roughness of the small hole wall, the chisel edge and the main cutting edge should be properly repaired (it is best to rough the grinding machine first, and then on the oil stone).
2. Accurate marking is the basis
Accurate marking with a height ruler should first keep the standard and accurate. When marking, the angle between the marking needle angle and the workpiece scribing plane constitutes an angle of 40~60 degrees, so that the drawn lines are clear and uniform. To pay attention to the selection of the marking reference surface, the reference surface to be processed accurately, to ensure its own flatness and verticality with adjacent surfaces. After the hole position crosshairs are drawn, in order to ensure that it is easy to find alignment when drilling, use the center punch on the cross line to rush out the center point (the punch point is required to be small and the orientation must be accurate).
3. Correct clamping is the key
Under normal circumstances, for holes with a diameter of less than 6mm or less, if the accuracy is not high, you can use hand pliers to clamp the workpiece for drilling. Regarding the hole of 6 ~ 10mm, if the workpiece is smooth, it can be clamped with flat pliers, but should make the workpiece surface and drilling machine spindle vertical. When drilling a hole with a large diameter, the flat pliers must be fixed with a bolt pressure plate; For larger workpieces and the diameter of more than 10mm, the use of the pressure plate clamping method for drilling.
4. Accurate search is the key
At the end of the workpiece clamping, do not rush to drill, should be the first to find the right. There is static and dynamic positive finding. The so-called static correction refers to the correction before the drilling machine is initiated, so that the center line of the drilling machine spindle and the intersection of the workpiece crosshairs are aligned. This method is safe and convenient for beginners and is easier to grasp, however, the drilling accuracy is low because of uncertain elements such as the swing of the drilling machine spindle, the drilling accuracy is low. Dynamic search is to find the right after the drilling machine is initiated. Together, some uncertain elements are taken into account, and the accuracy is relatively high.
5. Careful testing is not less
The detection can accurately and timely find the accuracy of the hole, so that the necessary measures can be used to compensate. For holes with high drilling accuracy, drilling, reaming, and reaming are generally used. After drilling small holes in the first step, use calipers to detect the fault offset from the center of the base hole to the reference surface, and calculate the position of the bottom hole and the ambition center by measurement. If the amount of fault is not more than 0.10mm, can be in the reaming, appropriate increase the top angle of the drill bit, weaken the role of automatic centering, to properly promote the workpiece by the positive direction, and gradually increase the diameter of the drill tip to compensate. If the fault amount is greater than 0.10mm, you can use the assorted round file to trim the two sides of the bottom hole, and the trimming part should be connected with the bottom hole arc smooth transition.
