Sharpen the drill
The drills gradually slow down due to use and lose their chipping properties, so they must be sharpened again. Continued use of the slow drill may lead to breaking or softening of the drill tip. The wrong method will have the same results. If the drill is badly burned. It is necessary to stone and remove the entire burned area. A noteworthy point about cooling the drill when sharpening is that the drills should not be immediately cooled in water while sharpening, when the drill has a high temperature, let it Cool the air then continue working because the shock caused by the rapid cooling of the drill may cause cracks in the drill.
Three important points when sharpening the drill
Free angle behind the cutting edge
To effectively separate the chip by the cutting edge, the surface behind the cutting edge must have a slight free angle. Without this free angle, chipping by the cutting edge is not possible. On the other hand, if the value of this angle is high, the cutting edge will be weak. Less free will also cause a part of the back of the drill to be rubbed against the surface of the workpiece and the advance of the drill into the hole will be slow.
This is important in Kindle sharpening tools by the free angle adjustment lever and its value is specified in degrees on BSG 20 and BSG 60 machines, so the operator can consider the value of this angle by considering the material of the workpiece. Adjust.
Angle of inclination and length of shear edge
The type of workpiece material determines the proper inclination angle of the drill bit. The angle of both shear edges relative to the drill axis axis should be equal (for most cases the angle of each shear edge with the longitudinal axis should be 59 degrees.
If the inclination angle of the cutting edges is not equal, only one cutting edge performs the chipping operation and widens the resulting hole.
If the angle of inclination of the cutting edges and the position of the drill bit are both sharpened by error, the drill may fail very soon.
In Kindle drilling machines, the operator can easily adjust the desired angle on the main support of the machine and tighten the screw. Then, after sharpening one side of the drill, remove the fixture inside which the drill is sharpened. Then, without touching the initial settings of the machine, sharpen the other side of the drill. The face will be exactly the same.