- Double Margin
- Pilot Diameter
- Precision Ground
- Manufactured to Order
Performance Double Margin Step Drills from Boneham are precision flute ground using the latest in 5 axis CNC grinding technology. Double margin drills use a second margin behind the first to finish a hole with more accuracy and truer finish. The finish gains generated by the use of a double margin drill can frequently remove the need for a reaming operation. Double margin drills can come in two variants, raised land or backed off land. The use of the double margin profile is also known to increase tool wear significantly. When used with Boneham drill bushings, double margin drills become incredibly accurate due to the increased drill margin contact with the bushing wall.
Double margin step drills or piloted double margin drills have two diameters for a primary and secondary operation in one drill bit.
Can be manufactured to National Aerospace Standards NAS