Filletting Problem---again

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 From:  Brian (BWTR)
1342.1 
Sorry if I am asking the same question that has been answered before.
I went down this ring making exercise again with great care, I thought, but still got two curve points not connected. BUT, I found them more easily from the previous instruction advice.

But now, I thought I should be able to fillett the edges---have I done something wrong again? Am I asking for something that wont work in this instance?

EDITED: 30 Dec 2008 by BWTR

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 From:  Michael Gibson
1342.2 In reply to 1342.1 
Hi Brian, this is another instance of some misalignment between the arc corners and lines.

Here's what I mean - on the outer profile, I turned on control points:



Then I zoomed in closely to the area circled above. There you can see that it is arranged like this:



The rounded corner part is not tangent to the line it connects up to, there is a shallow angle there. Shallow angles like that will create difficulties for the filleter, it means the filleter cannot calculate a single smooth piece marching around that corner, instead it has to come to a corner piece and try to fill in the corner.

If the corner was tangent to the line instead of having a crease there, it would be easier for the fillet to be calculated.

To be able to fillet the end result, you're going to need to be more careful when you place those rounded corner parts in - they can't be just eyeballed to be within 4 or 5 degrees of being tangent, they need to be snapped on to be nice and smooth there.

One method that may be easier for you is to not try and manually draw the corners at all, instead use curve fillets to create them for you, that will ensure they are nice and tangent automatically.

To do that, create your outline with sharp corners on it like this:



If they are separate pieces, select them and use Edit / Join to make them into one curve.

Then select just that one curve, and run Construct / Fillet. Some points will appear at the sharp corners, and you can select which ones you want to be rounded:



Then pick a radius, just like you do for a solid edge fillet, but when applied to a single curve it will round the corners of the curve:




Placing rounded corners into your curve using this method will guarantee that the corners are all tangent with the neighboring line segments, that will avoid a lot of filleting problems later on.

- Michael

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 From:  Brian (BWTR)
1342.3 In reply to 1342.2 
Michael that is a bit of WOOF/WOW learning to working proceedures.(For me!)
Not complaining, but was there something I missed earlier, or is this an area of missing general working method in other apps that I have not also previously grasped maybe?
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 From:  Michael Gibson
1342.4 In reply to 1342.3 
It's common in drafting / AutoCAD type programs.

- Michael
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 From:  Brian (BWTR)
1342.5 In reply to 1342.4 
Thanks Michael.
I went through a working exercise and can see the method/principle'
More stuff to allocate to my poor old brain!

I have never worked with any auto cad type programme before (Does Amapi 7.52 count?)
I guess it is a problem for those of us who started from another direction of the 3D learning curve?

So many computer 3D "languages"!
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