Cross section quarter round
or quarter round?
The classical bits are halfend. In the
last years however a lot of users began demanding quarter rount bits.
Better chip removal due to the "more open" shape. Better
cutting results as the chips cannot be pressed against the material by
the back of the tool. This leads to better surfaces especially when
cutting aluminium or acrylic.
Rotation spees and feed rate can be raised by 20 - 30%, especially
within plastic material.
Less out-of-balance forces and thus less vibration caused by the tool as
the excentric mass is reduced and the center of gravity moves closer to
the axis of the tool.
The tip of the tool becomes weaker and breaks more easily. This however
should affect only tools with small width (b <= 0.20 mm)
or tools used with machines with little rotation accuracy or little
Yes. The advantages of coating apply
also for engraving bits. When it comes to regrinding the most important part
of the tool, the halfening flat, stays unground, so that the coating remains