[scottsss]

I need to cut a concave surface into some 316 ss. My speed is 4150 with a feed of 8.3 step over is .012 inches with a .75 inch end mill. Depth of cut is a maximum of .030. But I'm still getting noticeable lines...Any help would be great.

[djm77]

You need a much small step over and depth of cut. I usually leave around 0.3mm (0.012") to be removed on the finish pass and use a step over of between 0.05-0.1mm (0.002"-0.004").


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[awerby]

The milling strategy is important too. How are you cutting this concavity? "Waterline" toolpaths are good for steep areas, but tend to leave unwanted contour lines when it gets shallow. Parallel toolpaths are better for shallow areas, but they will leave lines as the concavity gets steeper. Sometimes you need to use both strategies in the same part to avoid leaving tell-tale marks on your parts. Of course, there are other strategies as well - what CAM software are you using?

[scottsss]

The part is 94 mm diameter with 85 mm having a radius of just under 6 ft. I don't have the print infront of me to give the radius exactly. I'm going down .018 inches to .019 inches..

I'm using sprutcam and a planar finish. I'm climb milling only.


QUOTE=awerby;1866304]The milling strategy is important too. How are you cutting this concavity? "Waterline" toolpaths are good for steep areas, but tend to leave unwanted contour lines when it gets shallow. Parallel toolpaths are better for shallow areas, but they will leave lines as the concavity gets steeper. Sometimes you need to use both strategies in the same part to avoid leaving tell-tale marks on your parts. Of course, there are other strategies as well - what CAM software are you using?[/QUOTE]

[awerby]

Since it's not a planar surface you're trying to cut, I'm wondering why you chose a planar finish strategy. Doesn't Sprutcam have a spiral toolpath option? You are using a ball-end tool, right?