Someone is asking me to make him a pair of speakers. The part I am struggling with is how to cut these facets/bevels on my CNC. I currently have VCarve Pro 11.5 and thought of building a jig/base with the proper angles to place the workpiece on and just use a spoilboard bit to mill the face flat. Possibly a lot of work to make the jig but relatively not a lot of machining time. Using Aspire i think I can mill the piece with it flat on the table but it is potentially a long carve.
The possibility exists that I may make a few of these as a low volume production item. Or it may just be this one pair. Does anyone have suggestions or advice for me?
You can just define a chamfer tool path using the diagonal edge and the angle between the surface and this bevel with a depth equivalent to the board thickness. It will then cut in air where the chamfer starts but the result should be what is on your picture.
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You mention Aspire. This could be modelled easily in Aspire and cut with 3D Roughing and 3D Finishing toolpaths fairly quickly. You’d easily be able to use a 3/8” or even 1/2” ball end cutter to do so with a reasonably larger stepover (say 1/32” or more).
The attached image shows as bench I did in VCarve using Rhino 3D models. Each angled facet was finish cut with a 1/2” ball end cutter. All 5 planks combined took not much more than an hour of run time (if I recall correctly) perhaps even less.
A corner bevel can also be cut using multiple parallel lines and the fluting toolpath. I have had good results for cuts similar to this using vectors spaced at 1/8" with a 1/2" end mill. Note that the upper edge of the cut will start the bit radius beyond the vector end, and the vectors must extend at least the bit radius beyond the edge of the material. The plunge rate for the tool should be the same as the feed rate, and the pass depth set to the flute depth, since the first pass barely touches the material and the subsequent passes are effectively a 1/8" Stepover.
An end mill with a flat end is used rather than a ball nose because the ball nose produces a scalloped surface, while an end mill produces a flatter surface.
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