convert spline to arc & line

[metalcut]

how to convert a 3d spline to arc and

line

[Kenneth Potter]

menu/modify/cnv_to_arcs/ set the tolerance "arc center" /select spline to convert/done.

[gmenzies]

I have had trouble with this . if the spline is a edge of a surface (hole) that I have used create curve /edge . it works . but if the spline is 3d or moves with a combination

of various arcs it fails. if I use modify/break/spline to arc . I get little line segments. the helps are note clear on examples in getting the results I need.

eg: I did a shape of several arcs that were tangent and projected them onto a shaft. this was done in solidworks . when I imported the geometry into mastercam (iges) and unwrapped the 3d splines . for 4 axis work . I was hoping to convert to arcs . instead I got only nurb splines and a lot of code for machining. the spline shape that was unwrapped . was one continuous spline.

any suggestions ?

[Allan Brown]

If you are 4axis machining you'll never get the arcs in the code on a typically machine, unless it supports it's own brand of rotary substitution. If you are wrapping an arc with rotary sub, the code with be linear.

In the Roll/Unroll fuction, arcs are not a target geometry - only lines or splines.

>how to convert a 3d spline to arc and

line

For arcs only use Modify/Cnv to arcs - target splines should be arcs defined as splines - not one long spline

For arcs and line use Modify/Break/Spl to arcs

For lines only use Modify/Break/Mny Pieces and specify your error tolerance.

The two main issues are tolerance and geometry. The spline must be able to be defined as an arc, and within the tolerance you specify.

[metalcut]

I already do but result is very small

segment arc create , should have look ahead

like nc filter

[Allan Brown]

If you like how the NC filter handles the spline, create a 3D Contour with the filter on, then backplot the operation with Save as Geometry clicked on. This is an old V6 Northwood Filter trick to use toolpath filtering as a geometry arc filter.