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Milling interior 3D edges

Message 1 of 5
238 Views, 4 Replies

Milling interior 3D edges

Everything I've read obout "mickey mouse ears" and "dogbones" only seems to apply to 2D milling operations. Is there any way to do something similar in 3D?


My part is a simple box with the bottom half of an icosahedron cut out of it. The idea is that a (positive) icosahedron would fit snugly into this hole. If machined as-is of course the un-machined interior radii would prevent the part from fitting. How can I mill out all the interior edges in order to allow the other part to fit?


I tried sweeping circles along all the edges with the pipe tool, but that gives me something way too conservative. I also tried manually, painstakingly, building an "inflated" version of the positive part (see second attached image), where each of those spheres and cylinders kiss the outer vertices and edges of the original geometry. That's closer to what I'm after, but not quite. The problem is it doesn't take into account the direction the tool is coming from. I.e. the sphere centers are "in" (towards the part center) by the tool radius rather than being "up" (relative to the machining direction) by the tool radius.


Another thought I had was to sweep a vertical cylinder (which approximates the tool) across each of the edges, but the sweep tool can only sweep 2D profiles, not 3D bodies. So I'd have to find a projection for each edge one at a time to sketch a perpendicular shape to sweep, and then again sweep them all one at a time. Surely there's a better way?

Message 2 of 5
in reply to: starskipper

I would try some of the 3D paths, pocket clearing then maybe scallop or flow and adjusting the parameters based on your needs.  You might need to combine several tool path types to get exactly what you are looking for and it might take a bit of tinkering to work it out.


Good luck!

Message 3 of 5
in reply to: starskipper

Are you trying to solid model the shape into your square block?



Message 4 of 5
in reply to: jaredSADUH

Thanks for the suggestion. Do you know which parameters I should try? Note that Stock To Leave wouldn't work here as I need all the faces to be exact in order to grip the part; it's only the edges that I want to dig out.


Another complication is that the edges under the vertical faces need to be treated differently from the edges on the bottom. In the latter case I want the toolpath to ride the edge exactly, while in the former I want the side of the tool to ride the edge (if that makes sense).

Message 5 of 5
in reply to: leo.castellon

I'm not sure if I understand what you mean, but basically I have two parts: one is the "main part" (happens to be a regular icosahedron in this case) modeled and machined separately, and the second is this square block with a slot cut into it. The first part needs to be inserted into the second and fit snugly, while also being end-user removable and replaceable. Note that the exact shape on the interior of the second part doesn't matter, just as long as it can repeatably hold the first part in the exact same position every time.

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