REST for 3D Roughing and Finishing

REST machining for 3D would be great. Currently, we can do only a 3D roughing and finishing pass. I know we can do multiple finishing passes with a smaller tool each time, but that doesn’t save any time.

Current example:
3D rough with 1/4 = 40 min
3D finish with 1/16 = 57 min

So - add another finishing pass to try and speed up the 1/16 and we’ll currently get:
3D rough with 1/4 = 40 min
3D finish with 1/8 = 22 min
3D finish with 1/16 = 57 min (same as before, and now cutting a lot of air)

Expected result:
3D rough with 1/4 = 40 min
3D finish with 1/8 = 22 min
3D finish with 1/16 = waaaay less than 57 min

Don’t know if it matters to do REST passes in rough or finish. I guess rough/finish is already REST, but limited to 2 passes.

We haven’t looked into the feasibility completely but it’s on the wishlist for V8.


Roughing rest milling should be (relatively) easy. You already have the code for pocket milling.
And 3D roughing in CC is really 2.5D Roughing (Z-Level), which is just a series of pockets.

Finish Rest Milling will be a challenge. You have to keep track of the IPW (In Process Workpiece) which is the original stock minus any material removed from previous operations.
then you have scallops, left by the ball mill. So how does the software ignore the small scallops left by a previous finishing operation with a larger tool, but cut the material left in corners?

@jac , any chance you’d be willing to share your test file with those times?

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Here’s a sample with normal rough/finish (file attached):
1/4 rough at 45 min
1/6 finish at 55 min

Add a 1/8 rough to speed up the finish pass and you get:
1/4 rough at 45 min
1/8 rough at 369 min
1/6 finish at 55 min.
That 1/8 rough should be a fraction of the time and should reduce the time of the 1/16.

So maybe add a REST finish instead of rough:
1/4 rough - 45 min
1/8 finish - 20 min
1/6 finish - 55 min

That 1/16 finish should be less if following the 1/8.
3dREST.c2d (284 KB)

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OK, first… you can cut 95% of this part with flat end mills. The other 5% is the contoured areas.

If you make 2 offset boundaries that only cut what they need to, Green for your 1/8" ball, and Red for your 1/16" ball, you can get those times down a lot. The red area basically being your “Rest Milling”

I didn’t like the transition from the 1/8" to 1/16" ball, so I just finished the contour with a 1/16"
Total time 31 minutes (calculated)
I used 0.0001 for depth on the surface path. It will round this off to 0.000. But if you edit it, you need to enter the 0.0001 again.
2nd path pockets down 0.280, just a bit above the contour.

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Thanks for this. I’ll learn quite a bit from studying your answer. Unfortunately, this is just a sample project/file to show how 3D REST would be a big help in general - though maybe not for this specific file. I still hope Carbide3D can add 3D REST roughing to v8.

@Tod1d I’ve studied this and don’t quite get it. Can you elaborate on exactly what your 4 toolpaths are? Or attach an updated version of my file? I think if I could examine your actual paths and vectors, it would be an a-ha moment.

3dREST_optimized.c2d (1.8 MB)

The first path just surfaces the top.
The second pockets out the opening down to a bit above the highest point on the 3D contour
The third pockets all the way through
And the 4th does the 3D finish on the contour

Thank you. This is a tremendous help.

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