Another common type of hole is a stepped or stepped and chamfered hole. Typical applications are components with screws or bolts where the head needs to be ”hidden”.
Step/chamfer holes in one pass
Tailor Made and Specials to your request
Solid carbide drills – Available with steps and chamfers.
CoroDrill 880 – Steps and chamfers to your request.
Stepped holes by drilling two holes
Solid carbide drills or CoroDrill 880 – Choose drills by hole sizes and depths.
Stepped holes by drilling and boring
Solid carbide drills or CoroDrill 880 plus CoroBore 820 or DuoBore – Choose drill and boring tool by hole size and depth.
Stepped holes by helical interpolation
CoroDrill 880 or CoroMill cutters – The step diameter hole can be 2 x DC. Helical interpolation with CoroDrill 880 is a slow operation and should not be used for deep steps. Choose CoroMill cutter by hole size.
Non-rotating drill
Choose a standard CoroDrill 880 drill and programme the tool path.
How to apply
Step/chamfer holes in one pass
The challenge, when using a multidiameter tool, is to achieve good chip breaking from all edges in the cut. In long-chipping materials, like low carbon steels and stainless steels, the initial tests should be made in steps:
- First, check chip formation from the drill
- Check chip formation from the step insert
- Check chip formation from chamfer insert
Stepped holes by drilling two holes
First larger diameter, then smaller.
Always start drilling the large diameter to assure centering of drill point and avoid chipping of cutting edges.
When drilling the small diameter with a CoroDrill Delta-C or a Coromant Delta drill, make sure that the drill point angle is equal or smaller than the large drill to ensure that the point hits the workpiece first.
Stepped holes by drilling and boring
Start with drilling then boring.
Stepped holes by helical interpolation
See Milling to learn more about hole making with milling cutters.