Surfacing help!

[Thorpydo]

Hey,

I'm making a two part mold with some surfacing. It's the most complicated part I've made so far and am a bit over my head.

First the background:

I've setup a rough surfacing feature and a fine surfacing feature in mastercam for a 3/8" carbide ball end mill. I will follow with a fine surfacing feature with a 1/8" ball end mill. The surfacing path that I'm using is parallel. The rough feature leave .1" to the surface, the 3/8" fine leaves .02" and the 1/8" fine takes off that last bit. The machine is the X3, a small benchtop mill.

The problem I'm facing is this:
During the 3/8" fine cut, it's taking off .08 down, but also .08 at the edges, and these edges can be a half inch deep. The machine doesn't like that and I have to slow the feed rate way way way down to make it even manageable.

If I was doing this over, I probably would have 3/8" roughed to .03, then 3/8" fine to .015, then 1/8" fine to the surface.

But I'd like to hear from you guys, what would you recommend? I've looked at the contour surfacing path in hopes that if it starts from the top, then I'm only ever taking a little bit off. . . but that doesn't look to be the case and the path is pretty funky.

Would you guys recommend roughing with a flat endmill instead? The ball doesn't seem to cut as well (my guess would be because towards the center doesn't rotate as fast as the outside)

Thanks!
Adam

[Delw]

the problem is the 3/8 has to leave that much stock or it will cut out places that you dont want it to. another words your endmill is too big for final rough pass.
use a smaller full rad endmil. as another step.

for example
you have a finish rad. of .075 and alot of stock to hog out.

use your 3/8s for rgh then a 3/16 for a semi rough then finish with a 1/8, or you can just rough and finish with a 1/8, depends on how fast you run and how much stock you want to take off.

[mc_n_g]

Take a semi-roughing cut with the 3/8 but at a smaller step over and more speed after the major rough. It looks like your cusps after the cut are large. You need closer spacing so the other mills can handle the cut.