CNC Machined Parts

Design Feature	Guideline	Comments
Interior Corner Fillet	R Depth / R Edge <4 R Edge = 1.3 X R Tool	The larger the radii, the lower the cost
Floor Fillet	Less than wall radii	Allows use of standard ball nose mills
Hole Diameter to Depth Ratio	Less than 1:10	A ratio of 1:4 is optimal
Thread Depth	Length < 2 X Diameter	Use inserts for plastics
Additional Hole Depth	Add an unthreaded depth equal to 50% the hole diameter after threads or inserts	Allows room for tool leads and chip evacuation
Cavity Width to Depth Ratio	Depth < 4 X Width	Use corner reliefs where tight assembly fits are needed
Wall Thickness	Metals > 0.76 mm Plastics > 1.52 mm	Avoid designing walls at minimum thickness. Thicker is always better.
Machined Text	20 pt Sans-Serif	Use engraved text
Edge Chamfer	45 degrees	Use chamfers instead of fillets for edge breaks to lower cost