machining with ball end mills

[Quickmike]

Does anybody have some "rules of thumb when using ball end mills for roughing or finishing? I have heard 10% stepover and 10% depth of cut.(10% meaning 10% of cutter diameter. Any suggestions would be greatly appreciated. Thanks in advance.

[Greg Williams]

Quickmike,

It really depends on what Diameter your talking about and how rigid your machine tool, Collet chuck and setup are. 10% is the rule of thumb for depth. As for stepover it depends on the required surface finish, I have used anything from 1mm to 0.002mm. Hope this helps a little.

[P_Scott]

Quickmike,

 

Whether roughing or finishing with a ball end mill you must keep more than the depth and stepover percentage in mind. A ball end mill has NO flute at the tip of the tool. This means there is no cutting going on at the tip. You can actually argue that the very tip of the ball does not spin at all. The best place to machine with a ball end mill is on the side of the radius, between the tangent point of the radius with the straight side of the tool, and the tip. For this reason, one should always consider programming with a ball end mill from open areas of stock, or previously machined areas, coming in from the side to the area that needs to be machined. A lot of male parts are typically machined from the bottom up, or outside to inside, with ball end mills. There are many parameters to consider. One cannot make a base judgement on Depth and Stepover alone. Stepover will determine the size of the scallop but if your surface is more wavy than straight, you will have to consider how the tool will Follow the direction of surface with direction of cut. There is training available from your Mastercam dealer, or other schools. Someone who is experienced in this type of work will tell you that every job has it's own challenges to overcome. Sorry for the long post. HTH

[cadcam]

quote:

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Someone who is experienced in this type of work will tell you that every job has it's own challenges to overcome.

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This is really how I feel.

The shapes all was tell me becuase they always change.