CNC centerline toolpath data export question for manual 3D contour development: Is it at all possible to export—in DXF or DWG format—a JOINED 3D polycurve—comprised entirely of tangent arcs and lines (i.e., NO NURBS or splines)—without the Rhino export engine meddling with the underlying (geometrically valid and simple) polycurve curves?
The desired 3D output would be the exact data set of Z-axis stacked, Ogee-ed contours—again, only arcs and lines—but simply tied together within Rhino into one long, valid, “open polycurve with 107 curve segments”) centerline tool path AND saved in AutoCAD AXF or DWG format.
From the numerous Rhino Forum threads (specifically #22469 and #86445), wiki.mcneel.com, docs.mcneel.com for CNC/CAM, laser/waterjet data prep, it appears that the only way to “save” the original arc & line data is to explode any/all polycurves prior to export which, unfortunately, defeats the whole purpose of tying the contours together into one long polycurve within Rhino and exporting.
Note #1: the original contouring data is “G-Code friendly” arc and straight line-only data. Everything is tangent; the data is really clean. We know how to create the necessary geometry. #OldSchool
Note #2: I have run numerous tests using the “Convert” command with different settings using the CAM Imperial and other export schemes (including the R12 and R14 format factor). As long as the polycurve is not exploded, everything always blows up the underlying tangent arcs and lines data into segments.
Note #3: The Rhino-exported “toolpath of ten thousand segments” CNC toolpath data runs but the export geometry (a) is simply huge compared to the simple and elegant original data and (b) has way too many random “stop-starts” inevitable with segmented data.
Note #4: Our CNC router’s CAM system version can’t accept STEP or IGES. Short a $17K controller lobotomy/upgrade, we are limited to DXF and DWG data input. We would just like Rhino to squirt back the arc and line data we developed… but with all the contour polycurves tied together and in DWG or DXF format.
Note #5: Currently using Rhino 5 (I can’t get the V6 license (re)activated for my office PC until tomorrow).
What am I missing?
I apologize for this being so long and involved. What we are doing—manually developing 2-1/2 dimensional edge and profile contouring toolpaths and how we are doing it—may seem unnecessarily “old school” but we have our reasons for wanting to teach our students these geometrically-based problem solving and product development skills. Thank you for your time and attention in this perplexing matter.