Difference between rounds

[johni]

This may be simple for some, but could someone explain the difference between a 'Rolling Ball' round -vs.- a 'Normal to Spine' round. Sometimes when applying a round, one will work and the other will not. I'm not sure why and am now curious as to not only why, but to also what the difference is between the two. Thanks in advance!!

 

[solidworm]

first image(normal to spine): highlighted curves are intersection curves(between the radii surface and planes normal to the spine curve at different points along the spine) as the analysis shows, they are arcs. (you can think of the the resulting surface as a blend between these arcs, and you actually specify radius of these arcs as input.)

my understanding is that the rolling ball creates the surface as if a ball with a specified radius is rolling between two surfaces and always touches them. the resulting surface will always be tangant to the ball and the 2 surfaces. (suppose there is a volume of clay at the corner of two surfaces, a ball which is supported by the two surfaces, rolls on the clay, forming it)

image: normal to spine
image: rolling ball
(y axis is radius)



Edited by: solidworm

 

[jeff4136]

If I understand correctly; for the rolling ball solution the
ball center traces a curve which is than used to sweep an arc
(normal to trajectory, ends at ball 'contact' points) section.
The sweep can be altered subtly or quite dramatically by
specifying an alternate sweep path / spine curve.


The best way to get an idea is to play with it and, as solidworm
illustates, examine the results.


2008-12-17_101706_prt--wf2--.prt.zip


As to why one or the other fails; it would have to be addressed
on a per instance basis (and then we might just be guessin').