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how to improve faceting quality when saving to 3D printable file types
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May 24, 2017, 04:25:50 AM
If I save a .tcw file to a .stl or .dae for printing at shapeways,   I get fairly crude faceting simplification in those files.   I tried the 'quadratic simplification' MESCHLABS filter but wasn't successful in getting better resolution - just distortion.  I have some intricate curves that I needed printed as closely as possible to my true solids Turbocad model.  Any suggestions on settings or filetype, etc to help with this?

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Chris Knickerbocker
Turbocad 2017 Pro Platinum, Turbocad 2015, 18 Deluxe,
18.2 Platinum
i7 4970K 4 core, MSI H81-E33 Mboard with 8GB RAM
AMD Radeon R250 graphics ...
Software engineer trying my hand now with real materials...


* May 24, 2017, 05:30:10 AM
#1
You need to play around with the ACIS settings (I assume your using the v18 pro) and in particular with the custom faceting settings, in v18 one can only switch from draft to quality, but clicking Custom allows for finer control.

For example, reducing the normal tolerance to 1 will produce a very fine mesh  but it will slow down TC, experiment with the settings to get a good balance which will save to stl as required.

see faceter modes in the wiki, http://www3.turbocadcommunity.com/tiki-index.php?page=3D+Drawing+Setup#Faceter_Mode

## Forgot to mention, to see the mesh, ensure Options menu - ACIS - degenerative faceting is turned off,  and turn on options menu - drawing setup - draw form building edges. ##
« Last Edit: May 24, 2017, 05:37:31 AM by Andy H »

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May 24, 2017, 10:25:39 AM
#2
I need to update my profile since I'm using  Pro Platinum 2017.   For starters, just setting the slider quality to maximum has helped alot.  Thank you! 

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Chris Knickerbocker
Turbocad 2017 Pro Platinum, Turbocad 2015, 18 Deluxe,
18.2 Platinum
i7 4970K 4 core, MSI H81-E33 Mboard with 8GB RAM
AMD Radeon R250 graphics ...
Software engineer trying my hand now with real materials...


May 25, 2017, 08:56:03 PM
#3
On a related note, I am trying to understand 3D printing better.  It appears like the different filetypes used for the printing are surface model based,  similar to the TC surface representations of 3D objects.  My understanding is that the TC true solids modeler is 100% accurate in its representation of 3D objects.   If this is true,  why can't 3D printers and displays read a true solids file and produce a printed object or visual display without having to draw polygons?  (instead just a 3D raster???)  It seems like alot of complication and error happens with these mesh polygons.   I realize this is all rather vague but if  anyone can provide some enlightenment of my ignorance, please do. ::)

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Chris Knickerbocker
Turbocad 2017 Pro Platinum, Turbocad 2015, 18 Deluxe,
18.2 Platinum
i7 4970K 4 core, MSI H81-E33 Mboard with 8GB RAM
AMD Radeon R250 graphics ...
Software engineer trying my hand now with real materials...


May 25, 2017, 11:41:34 PM
#4
Solid Models are better for curves, yes, but I expect that STL is used because developers and manufacturers don't have to pay a large royalty.

TurboCAD Expert and Deluxe are both Surface Modelers.  They can render equally well.  The $350 difference in price is due to the extra commands and configurability available in Expert.

TurboCAD Pro Platinum is the only Solid Modeler in the lineup.  The extra commands (like Bending, Quick Pulling, etc.) all very useful, but would only add $400-$600 to the list price over Expert (IMO) if they used the same modeling engine.  The $1,000 price difference is due, in large part, to the licensing fee for the Dassault Systems ACIS Solid Modeler.

I expect the same would be true of the 3D printers (some of which are available for less money than what I estimate is the licensing fee for a Solid Modeling engine).

And then there's the different Solid Modelers that are out there.


Jeff

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TC Pro Platinum 2017, 2016 & 2015 (all with LightWorks) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1


* May 26, 2017, 09:44:23 PM
#5
.stl is the default file used by most additive 3D printers because it was invented for that, and long enough ago (mid 80s) that there were almost no CAD modellers that used curved surface representations.  I don't know if .iges had even got that far then.  That being said, .stl is simple, universal, and because it's meant to be an output format, not a modelling format, you can increase the faceting resolution of your modeler.  It works like a TC surface modeler because modifying it proportionally transforms the vectors between vertices, not the parameters of the surfaces between them, so it doesn't destroy their compliance with .stl rules because it doesn't change the relationships between faces, edges and vertices.  Even in TC deluxe, use high-count polygons, and extrusions and cones of them instead of the native primitives to improve resolutions.   It's not meant to be a modelling format because, if you boolean two objects with different mesh densities together, boundaries become hopelessly complex to try to comply with .stl file rules, which stipulate how many facets can share vertices and edges.   
The ACIS kernel isn't that expensive, because TC Mac has it for US 130, so IMO, PC TCadders are being short-changed, even if MacFolk are donating arms and legs for nice hardware.  There's even the OpenCascade open-source (free) kernel that could keep the price down and give .igs and .stp and b-rep curved surfaces.
Even if 3D printers could interpolate curves in x and y, they'd still be layered/stepped from the incremental lowering of the platen.  There's an Irish-built 3D printer that uses what's called "layer-object-manufacturing", LOM.  It cuts profiles out of sheets of A4 paper and laminates them together, so the raw materials are just paper, knives and a spot of pva glue, very very low cost.  Reams of 80 GSM A4 paper are 50mm thick, so the layer resolution is .1mm...  it's called "Mcor Matrix", if you're interested.   3D Systems released an LOM file format, .slc  at the same time as .stl, it's just layers of closed polylines, you stipulate the thickness.
 NetFabb, the .stl diagnostic and repair program, can produce .slc models from .stls, and animate passing through the slices, like flip-pad animations or MRIs and CT scans on TV medical shows.
Converting a curved object into a polygon object isn't very complicated, renderers do that to simplify raytracing.  It gets more complicated when facets have to have defined normals so the machine knows which side is inside the volume (solid), vertices can only share x facets, and edges can only share y facets, it has to be manifold, (watertight), and there can't be duplicated facets, vertices or edges.  Y'see?  .stl format is deceptively simple, creating a compliant one from something else isn't. 

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* July 19, 2017, 03:00:00 AM
#6
If I save a .tcw file to a .stl or .dae for printing at shapeways,   I get fairly crude faceting simplification in those files.   I tried the 'quadratic simplification' MESCHLABS filter but wasn't successful in getting better resolution - just distortion.  I have some intricate curves that I needed printed as closely as possible to my true solids Turbocad model.  Any suggestions on settings or filetype, etc to help with this?

Have you tried exporting it in .WRL (.VRML) file format from turbocad and utilizing this format in shapeways?. You can utilize curve approximation variable to tune curve resolution. I hope you don't face any VRML 1.0 / 2.0 version errors in between  :-\
« Last Edit: July 19, 2017, 03:47:20 AM by Shaheryar Rafiq »

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Shaheryar Rafiq
SQAE
IMSI/Design


July 19, 2017, 05:07:55 AM
#7
Have you tried exporting it in .WRL (.VRML) file format from turbocad and utilizing this format in shapeways?. You can utilize curve approximation variable to tune curve resolution. I hope you don't face any VRML 1.0 / 2.0 version errors in between  :-\

If you have to approximate curves, you may as well do it in STL.  If setting Faceter Quality to 100 (the ACIS menu item under Options) doesn't make it smooth enough for your requirements, then you can activate Expert Faceter Parameters and experiment with the options such as Maximum Edge Length or Normal Tolerance.

Shapeways can accept OBJ files (OBJ supports ACIS Solids as well as Surfaces), but the OBJ files created by TurboCAD have to have the Save 3D objects as Polygon Mesh option selected under Setup in order to be accepted by Shapeways and that won't get you smooth curves.  This has been a problem for years; guess I should report it again.


Jeff

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TC Pro Platinum 2017, 2016 & 2015 (all with LightWorks) & V21
System: i7-5820K @ 3.30GHz, ASRock X99 Extreme4, 16GB DDR4-2133 RAM, Gigabyte GTX 970, Samsung NVMe SSD 950 (256GB), Windows 7 Pro (64-bit) SP1