Car Rim: Dealing with seams

 From:  Michael Gibson
2103.4 In reply to 2103.3 
Hi Jason, yes a pattern approach where you focus on one slice that is replicated can get some more control over revolved seams, since that doesn't end up with just one area of the structure having a different topology.

But it should be possible to get rid of those little edges in the case you have here with a bit more precision in just a couple of the pieces.

One thing that I would recommend is to build this object centered at the origin so that you can make more easy use of the axis snaps to make sure pieces are fully aligned, and it is easier to use the origin snap as a center reference point.


Examining your curves a bit here, I took a look at this curve:



And zoomed in closely to the circled area to see how it was aligned to the revolve profile (which is the vertical line in this view):




That one looks good, it is lined up right on it.

Now same thing on the second inner profile (I think these were lofted together to make the protruding surface part?):



Zooming in a bit:




It looks like that is probably the source of your small edges right there - the endpoints of the segments of that smaller piece are not aligned horizontally with the revolve axis.

If that piece was aligned, it should made for an exact join between the revolve seam and that adjacent protruded surface seam, avoiding creating any tiny edges.


Another separate issue than that is curve segment tangent alignment. If I take that original curve I showed above, and use Edit/Separate to break it into individual segments, then delete half and turn on control points:



Creating an extended horizontal line through the first point and zooming in there:




You can see that those points are not aligned horizontally with one another - that means that the curve tangent is not exactly perpendicular to the mirror axis, which means the mirrored parts are not totally smooth, it would help with filleting if those 2 points were initially horizontal (you can use Transform/Align to help ensure this), making those meet up in a smooth manner. Things that meet in a sharp manner tend to need more difficult fillet processing to try and match the ends or to attempt to put in corner pieces.

I would like to make some of these things more automatically adjusted in the future, but for now it is something that you need to watch out for. It tends to help out a lot for filleting in particular to have the original curve framework more fully aligned up.

Hope this helps,

- Michael

EDITED: 23 Oct 2008 by MICHAEL GIBSON