Export pieces of an object?

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Export pieces of an object?

jazzjohn
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New user here. My first design is sliced into two complex shapes. Is there a way to export each piece into a separate  STL file? The design is too complex to easily subtract out cubes, etc.  to  free each piece.
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Re: Export pieces of an object?

Marijan Pollak
It may not be easy to do, If parts can be separated then do each piece in separate program. If pieces are normally one atop another You can separate them this way.
Maybe Puzzlecut can help, too. But what is reason You want them separated?
You can also write program that draw each piece You want to separate in paralel and make Union at end so You have whole piece to control if it all fit together properly and then simply disable one Module and save .stl file and repeat same with other  module.
You should also have have some connecting elements or leave holes for screws.
Most complex is to be sure that You would be able to put them together, as You I asume need one part at end. But what is the main reason, they are simply too large to be printed as one piece?  
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Re: Export pieces of an object?

MichaelAtOz
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In reply to this post by jazzjohn
Depends on your code, but you can prefix one set with '%' that bit will preview grey, and won't render, so you can export the non-prefixed bit. Then invert the prefixes for the other set.
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Re: Export pieces of an object?

jazzjohn
In reply to this post by Marijan Pollak
I want to get a close fit (one piece slides into the other) so if they were printed unassembled, the gap could be minimized. I have the gap set at .005 inch, but have no idea how that will work on the printer (Again, my first design!).

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Re: Export pieces of an object?

jazzjohn
In reply to this post by MichaelAtOz
The design is all based on subtracting shapes from one cube, so I don't see how I can grey out one part of the main cube but not the other.
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Re: Export pieces of an object?

MichaelAtOz
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If you can share your code it would be easier than guessing.
Admin - email* me if you need anything,
or if I've done something stupid...
* click on my MichaelAtOz label, there is a link to email me.

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Re: Export pieces of an object?

Ronaldo
If you have subtracted the gap from a whole piece, you will not be able to have them in separated stl files.


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Re: Export pieces of an object?

jazzjohn
Ronaldo wrote
If you have subtracted the gap from a whole piece, you will not be able to
have them in separated stl files.

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Yes, that makes sense. Maybe another program like Meshmixer can do it with the STL file.

On a related note, is there a rule of thumb for the minimum width of a vertical gap a printer with ABS material can handle?

Thank you all for the responses. This a a great and helpful community of users. Glad I found OpenSCAD!
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Re: Export pieces of an object?

nophead
The minimum gap is purely a function of printer accuracy / filament accuracy. On a perfect printer with perfect filament it would be zero. In practice it depends on backlash, filament diameter variations and the synchronisation between feed rate and flow rate during acceleration, etc.

On 28 February 2017 at 14:35, jazzjohn <[hidden email]> wrote:
Ronaldo wrote
> If you have subtracted the gap from a whole piece, you will not be able to
> have them in separated stl files.
>
> _______________________________________________
> OpenSCAD mailing list

> Discuss@.openscad

> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org



Yes, that makes sense. Maybe another program like Meshmixer can do it with
the STL file.

On a related note, is there a rule of thumb for the minimum width of a
vertical gap a printer with ABS material can handle?

Thank you all for the responses. This a a great and helpful community of
users. Glad I found OpenSCAD!



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View this message in context: http://forum.openscad.org/Export-pieces-of-an-object-tp20615p20643.html
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Re: Export pieces of an object?

adrian
In reply to this post by jazzjohn
If that image is the object, then you can create a linear extrusion of a polygon, move it over to the locaion you want using rotate() and translate() and use difference() and intersection() to pull out what you want.
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Re: Export pieces of an object?

jazzjohn
In reply to this post by nophead
Nophead:

I posed the question to the company that makes the Statasys uPrint SE Plus printer and was told the minimum gap should be at least .030 inch (3 layers) to make sure it builds correctly.

Not the answer I wanted since the current gap in the design is .005 inch.
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Re: Export pieces of an object?

nophead
I thought you meant the vertical gap between between two parts separated horizontally. If you mean a horizontal gap between two parts separated vertically then it would need support material in the gap, so that is probably why they specified a number of layers.
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Re: Export pieces of an object?

jazzjohn
In reply to this post by adrian
adrian wrote
If that image is the object, then you can create a linear extrusion of a polygon, move it over to the locaion you want using rotate() and translate() and use difference() and intersection() to pull out what you want.

It's not an extrusion. the V shaped cutouts are actually tapered and were created from subtracting multiple hulled spheres. I did not know it was going to be two pieces in the beginning, but then the issue came up with the first prototype (the usual time for mistakes to be uncovered!) To create an extrusion to capture tapers in different directions along the center piece would be very tedious.

I guess I'll have to chalk up my first SCAD design to experience!

I am going to look into separating the pieces from the STL file using Meshmixer or ?
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Re: Export pieces of an object?

adrian
Then create a polyhedron. As long as the rails are straight, it shouldn't be horribly difficult.

Alternatively, if they are already separated physically from each other (I.e. The meshes of the two parts don't touch) export to an STL, import it into something like sketchup, and then you should be able to select each object separately by double or triple clicking on each object and export them.
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Re: Export pieces of an object?

adrian
When I say it shouldn't be horribly difficult, I mean you just have to enclose one of them from the other. Doesn't have to be exact.
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Re: Export pieces of an object?

Neon22
As a side note - when I've made connecting objects like this I have needed to control the slop between the pieces quite carefully to get a tight fit.
You can't really precalculate this amount until you print it. But at a layer height of 0.15 you probably need 0.5mm gap between the internal and external parts so they will fit.
The reason is that the extruded plastic will swell out and be slightly wider than the expected geometry. Depends on your filament and nozzle, pushing force and a few other factors, all of which makes it impossible to precalculate.
IMHO you should incorporate this gap factor into your design code so you can adjust it as you make test prints.
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Re: Export pieces of an object?

jazzjohn
In reply to this post by adrian
adrian wrote
Then create a polyhedron. As long as the rails are straight, it shouldn't be horribly difficult.

Alternatively, if they are already separated physically from each other (I.e. The meshes of the two parts don't touch) export to an STL, import it into something like sketchup, and then you should be able to select each object separately by double or triple clicking on each object and export them.
Something like you suggest worked great! I used Meshlab and was able separate the pieces. Thanks!

folder2inside.stl
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Re: Export pieces of an object?

jazzjohn
In reply to this post by Neon22
Good suggestions. Thank you.

Neon22 wrote
As a side note - when I've made connecting objects like this I have needed to control the slop between the pieces quite carefully to get a tight fit.
You can't really precalculate this amount until you print it. But at a layer height of 0.15 you probably need 0.5mm gap between the internal and external parts so they will fit.
The reason is that the extruded plastic will swell out and be slightly wider than the expected geometry. Depends on your filament and nozzle, pushing force and a few other factors, all of which makes it impossible to precalculate.
IMHO you should incorporate this gap factor into your design code so you can adjust it as you make test prints.
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Re: Export pieces of an object?

MichaelAtOz
Administrator
In reply to this post by nophead
nophead, where is your old post about the ID of holes, that's the best explanation I recall.

jazzjohn, for FDM printers you never get a square corner, the printhead movement always drags the extrudate inside the radius. So those square cuts will not be square. IIRC you want to open up the inside corner and flatten the outside. Like my very bad drawing in the corner here:
Admin - email* me if you need anything,
or if I've done something stupid...
* click on my MichaelAtOz label, there is a link to email me.

Unless specifically shown otherwise above, my contribution is in the Public Domain; to the extent possible under law, I have waived all copyright and related or neighbouring rights to this work.
Obviously inclusion of works of previous authors is not included in the above.


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Re: Export pieces of an object?

nophead
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