Solid Modelling and Offset shell

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 From:  TpwUK
5670.1 
Been playing with some solid modelling again, well rather making surfaces and then joining them up and the shelling the shapes. Is there a way Michael of making the Offset/Shell command stay planar ?

I can work around the problem but it would be nice to not have to.

Example of what i mean is attached below... If you do an Offset with the BodyBulge file .. The offset is 0.25

As you can see I have been working on some snap fit valves for tubeless tyres and Having to pull these pieces apart to fix the problem is a little tedious

Martin Spencer-Ford

EDITED: 26 Jun 2015 by TPWUK

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 From:  Mike K4ICY (MAJIKMIKE)
5670.2 In reply to 5670.1 
Hi Martin, those look pretty nice... where were these when I was making my turbine-tyre? ;-)
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 From:  TpwUK
5670.3 In reply to 5670.2 
Somewhere in the ether my friend - lol

Martin Spencer-Ford
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 From:  Michael Gibson
5670.4 In reply to 5670.1 
Hi Martin,

> Is there a way Michael of making the Offset/Shell command stay planar

Well, the edge of the generated offset is planar in your case here, it's just on a different plane than the input surface.

There is no way in the geometry library to generate a constrained partial offset like I think you're asking about - the offset that is generated is always a full offset of the input surface, if the surface normals of the input surface flare upwards or downwards then the offset surface will track along those as well.

If you want to make a partial offset, you can get that by trimming the offset with 2 horizontal lines to cut away the area that you don't want. That's normal that you might need to use more than one tool to finish a particular job - it's not really feasible in general for every command to try and build in too many options for trying to handle special cases, each command would become very bloated and complex.

There is no restriction for offset to only work on things that start out with planar ends on them, it can work on any kind of surface.

For something like you've got there it might be more convenient to work more at the curve level - generate an offset of the profile curve, trim that and then revolve both pieces to make your desired shape. Sometimes working more at the curve level can let you do a bit more localized stuff.

- Michael
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 From:  TpwUK
5670.5 In reply to 5670.4 
Thank you ... It makes sense too, i guess i should have used a fully closed curve as the profile .... Doh!

Martin Spencer-Ford
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