[skibbey]

The part in the attached JPG was created in Rhino 3. The blades were created by (i) projecting an eliptical arc on a cylinder, (ii) extruding that curve normal to the cylinder, and (iii) offsetting that extruded surface to create a solid that was then polar copied around the cylindrical core. The concave face of the blade is therefore normal to the cylinder, and the convex face is therefore offset (by .05").

Printing the part (via PolyJet) is no problem, but I need to mill one now so that I can use a material that is more resistant to pressure, temperature and moisture. I realize a 5-axis mill would make relatively short work of the part, but I only have a 4-axis setup. I've been hoping to use a constant z path, together with continuous 4th-axis movement, that will follow the blade contour to minimize z axis movement and tool marks.

One strategy that has been proposed (and tried) is (i) to create a single blade, or pocket between two blades, as though the projection onto the cylinder had not taken place, (ii) to create a tool path to mill that entity, and (iii) to wrap multiple copies of that tool path onto a cylinder. Unfortunately, the wrapping distorts the tool path and the blades end up with a wedge-shaped cross section instead of a rectangular one.

Does anyone have any thoughts on how to mill this part using my 4-axis machine without having to spend a fourtune on CAM software? I already have the latest version of Vector CAD/CAM, which is what I used to execute the unsuccessful strategy outlined above.

Thanks.

[pointcloud]

Hey I understand what you are wanting. I have rhinocam and some parts I would like to machine that way. I have a part now that I used the 4 axis index on and used a parallel finish in between the rotations (you could also use machine between curves and follow your blades between rotations).. I know there was not a constant A rotation. The out come of the part looks to be as close as I can get until they have a feature that would be described as 4th axis machine between 2 curves.... I hope Rhinocam's epople read this.. I would like a tool path that can flow like a tapered barber pole... and maybe a smooth conection or "a radial step" would do...

I hope this will help out a little...