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Old 27th August 2010, 09:09 PM   #1
mikehoulder
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Default How to obtain clean output from Boolean operations?

Hi folks. This is my first post.
I suppose it's to be expected. I'm still in my first few days with AC3D. But I am so *** depressed. I was counting on being able to get clean output from Boolean union and subtraction commands from AC3D. I've spent so many hours and days cleaning drawings by hand using these operations in other programs.

By clean I mean: every polysurface bounds a volume. That is there are no polysurfaces or lines for that matter which do not form part of a closed volume. My objective is to use yet another program with the AC3D Boolean output data to calculate volume moments of inertia. Here's the sort of thing I have in mind:

Subtract Drum (no.2) from Teeth (no.1). Union subtract output with Drum (no.2).
Union this output with Disc(no.3) to obtain Complete(no.4).

It does it fine; but it is not clean. There are invalid feathers of surfaces or edges which do not close the volume. It is the very devil to find them and it may take a full day's work to clean the drawing of these feathers.

Hopefully, in a few weeks, I'll laugh at my depression. Can anyone understand my problem and tell me "Yes, there is a way. Don't get depressed. Just keep plugging away and you'll get there. I know... I've done it!"?

Best wishes
Mike
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Old 28th August 2010, 01:47 PM   #2
Stiglr
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Default Re: How to obtain clean output from Boolean operations?

I don't think "clean" Booleans exist anywhere, with any program. They're always creating a mess, in my experience, especially if the shape you hope to arrive at is anything near complex (as a gear or bushing obviously is).

Best I've come to expect is that I can, relatively easily, identify groups of vertices I can weld together to produce the clean result.

With what you've got there, might I suggest trying to "trace" vertices to create a poly from a straight-on view of the result, and extrude that poly to get the finished product?
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Old 28th August 2010, 02:40 PM   #3
mikehoulder
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Default Re: How to obtain clean output from Boolean operations?

Thanks, Stiglr. Not so good news then.
I take your point about extrusion. But most of my drawing components that need to be put together don't have a constant cross-section about any axis.

What I've done in desperation in these circs is to redraw or trace using the Boolean union as a template - a very long job!

Ah well! Best to all
Mike
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