[3d Print] Proposal for Mesh Handling Workshop

[Cay Green]

Hi, 

I’ve been playing about with mesh manipulation programs a bit lately and I thought that it could be useful to offer to share what I've learnt in the form of a workshop with folk who might be interested. By ‘mesh’ I mean STL and OBJ files that are used in 3d printing. Sometimes if you want to modify a part before printing it you can't always go back to the original CAD file and often only have access to the ‘baked’ STL. In addition, if you 3d scan some geometry using cameras and use software to create a mesh, the results aren’t always brilliant. I thought it could be useful to spend a couple of hours showing some solutions to common problems. The software I would be demonstrating/using would be mostly (AutoDesk) MeshMixer - it has gotten quite powerful as of version 3 and it is still free (for now…) to download (Mac/PC/Linux). I thought the following activities could be useful:   

- Repair a model (intersecting vertices, holes)

- Modify a feature on a mesh model

- Mating Surfaces

- Boolean operations (not always as simple as they sounds…)

Any thoughts for other stuff to look at? 

Let me know if you would be interested and I can pick a time to pop up to Newcastle, maybe for a 3D Thursday or a weekend?

Best,

Cay  

[Jon Davies]

I would certainly be interested in knowing more about mesh manipulation, and think lots of others would be too.  Saturdays are always a temptation (it could be a themed day?), but i wonder if it would prevent the usual Thursday crowd.

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[glenb]

That sounds like a great idea, I'd be very interested

I have a couple of topics of my own regarding unifying nested or intersecting objects within STL files. Basically how to lose the occluded objects (which confuse the hell out of slicers)and simplify the mesh to just the visible outer shell. U have my own process which works for simple objects.

But Will also came up with a nice script (untested by me so far) to separate out the objects in a multi-object STL, load them into openSCAD, unify them into a single object then re-save the outer shell as another STL


Glen

[Cay Green]

Cheers. Two takers so far. Will need a couple more before I commit to coming up to do it. 

@Glen, Sounds interesting - not sure I fully understand the issue - do you just mean multiple STLs nested to maximise build platform space? As you know, slicers need 'manifold' (water tight, normals all facing outwards, mostly non-intersecting verticies (although not always...)) mesh files otherwise they kark. 

c

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[Glen Beestone]

exactly. i have come across files that have models hat are atualy made of interescting objects

 

so imagine in a 2D analogy,  wo ovelappiong circles like a ven diagram.

 

all you want in the finished object is the "Figure Eight" shape that the ouside of the cicles describes

but because the two cirles have not been properly unified you still have this ovelapping eliptical stucture inside that you don't need.

 

it wouldn't be too much of a hardship to print it if it was a simple model but as you say many slicers balk at it becuase they find sufaces decscribing the outside of a shape, inside of another.

and even if it did slice ok, if you had a model made of many intersting objects then you are printing a lot of uneccesary internal sturcture that you needn't

 

if you have the source file you can get rid of this no problem but if you have an STL made of intersecting shells, getting rid of the internal structure present becomes non trivial

 

Glen

 

 

 

 

 

Sent: Wednesday, February 03, 2016 at 12:49 PM
From: "Cay Green" <cayg...@gmail.com>
To: "north-ea...@googlegroups.com" <north-ea...@googlegroups.com>
Subject: Re: [Makers] [3d Print] Proposal for Mesh Handling Workshop

[Cay Green]

Hi Glen, if you send me an example STL (or point me at one) I'll see what I can clean up in the software I have...

Cay

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[Colin Jones]

Yes, very interested in that.

[Cay Green]

Hello, so, I'm still up for doing this, but think I'll time it for next time I'm up in NCL, which will almost certainly not be before Maker Faire. I realise that might not be the best time as people might be getting stuff ready for the Faire - I was thinking the Thursday before the Faire (3d Thursday...?) hopefully a couple of hours then will be ok? 

Best,

Cay

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On 6 February 2016 at 16:35, Colin Jones <maker....@gmail.com> wrote:

Yes, very interested in that.
   - Repair a model (intersecting vertices, holes)

[Colin Jones]

3D Thursday 21st April - looks like a good plan.

[Jon Davies]

Seconded.

On Fri, 26 Feb 2016, 15:39 Colin Jones <maker....@gmail.com> wrote:

3D Thursday 21st April - looks like a good plan.

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[Cay Green]

Cool, I've penciled it in!

c

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