Charlie....

I've been reading about Tapered RN bits for inlays. Example bit .25 mm diameter ball nose with a one side angle of 5.25 deg. Is the tool path calculated using the RN ? (Mostly  for surface contouring) Does the angle figure into the toolpath ? For medial axis carving. From what I understand RN is not recommended for inlays without some compensation, seems like mostly trial and error. Or am I totally missing something? I've done simulations and the offsets are off for RN tapered bits using the angle. Any insight you can provide would be great.

Thanks Joe....

Hi Joe,

For just about everything the geometry of the tool is considered when generating contours and cutpaths for things, including when generating a V-carving toolpath with the Medial-Axis Carving operation. For some of the 2D milling operations it is just treated like any other cutter.

What will probably throw a wrench in things is figuring out how to create the male side of an inlay that will fit properly with a female side that's been cut using a tapered ballnose unless you can somehow truncate the male plug to not bottom-out in the female side, without the plug just being a thin/shallow part that leaves a huge amount of space underneath.

Unless the tapered ballnose cutter's tip radius is narrow enough that it stays at one depth for the entire V-carve operation, you'll end up with the V-carve producing cuts with a radius matching the cutter's, like this:

This is made with an exaggerated tapered ballnose to illustrate what I'm referring to. You will want to not have any sharp corners in your design that cause the cutter to cut shallower, resulting in spots that will be difficult to produce matching male geometry for. You'd basically just want the tapered cutter to only perform a profiling cut at a fixed cut depth, rather than a proper V-carve cut where the cutter depth varies with the width of the shape being cut.

Otherwise you'll have to figure out how to make a matching plug like this:

Again, this is an exaggeration that's using a tool with a wide taper angle and a large nose radius, but the issue will still remain with a conventional tapered ballnose if used with the medial-axis carving operation. For any kind of relief carving, or 2.5D milling, a ballnose cutter's geometry is accommodated for though.

Hope that answers your question! :]

 - Charlie