Author Topic: WallThickness and 3D Printing  (Read 408 times)

Godfather

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WallThickness and 3D Printing
« on: January 21, 2018, 09:23:09 PM »
Hi everyone, and thanks in advance for your help.

I'm drawing a wing (actually half of one, split along the long axis)  I started by creating cross sections, and then using surface connect to generate a grid. The end result looks fine.  But when I upload it on Shapeways,  I get the message that the walls are too thin to support the object.

I went so far as to create an insert (basically a scaled down copy of the original piece) and did a solid subtract, so that it put a second mesh under the first.  Still got the same error.

When generating a wireframe -- how do I get the desired thickness?  Thanks!

Dr PR

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Re: WallThickness and 3D Printing
« Reply #1 on: January 21, 2018, 09:55:19 PM »
GF,

You did basically the right thing. You cannot define a grid thickness - they are all zero thickness, and that's why they cannot be printed.

First you need to create the desired outer shape grid, and it sounds like you did that. But, you have to close off all sides and ends to make a solid with no leaks. That's the tricky part, and you will have to experiment a bit. Add planes or grids where necessary to close the internal volume completely. Then select everything and use "Solids/Solid Define" to combine all the pieces into one solid.

Then you need to repeat the process to create a smaller solid with the necessary volume to subtract from the first, leaving the desired wall thicknesses. Again, you will have to experiment, but just making a copy of the original solid and scaling it smaller may do the trick. Then subtract it from the larger solid.

For 3D printing and STL file generation you will probably have better results of you make the solid a "Solid Surface." I think DesignCAD V2016 (26.2) has a leak test function to tell you if the solid has leaks, but I have never used it.

Phil
DesignCAD user since 1987

Godfather

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Re: WallThickness and 3D Printing
« Reply #2 on: January 23, 2018, 01:30:38 PM »
Thanks for your help.

I'm still having issues, but haven't given up. 

I don't see the option for solid surface. I'm using version 2015, so that might not be an option.

The problem that I'm running into is the graphics.  It's hard to tell what is what especially with the mesh in place.  It seems you can turn off hidden lines, but the mesh stays in place. When I do a render, this helps somewhat, but whenever I try to zoom, pan or change the view, the display goes back to the mesh again.

Does 2018 have better graphics? Don't get me wrong, I think that DesignCad is the easiest, most intuitive tool I have come across.  But the graphics are a bit difficult for me.

Walt

Rob S

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Re: WallThickness and 3D Printing
« Reply #3 on: January 23, 2018, 03:49:04 PM »
When you shade in 3D mode, in order to work in shaded view, you must use OpenGL shading, which allows Quick and Gouraud options.

That way it will stay shaded as you work, and allow zoom and pan and rotate etc.

I'm pretty sure V2015 (V25) did not have the solid surface option.

The basic graphics have not improved at all in the last two versions, unless you can use the RedSDK option, which allows some additional shading modes, some advantages, and some crashes as well.



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Bob P

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Re: WallThickness and 3D Printing
« Reply #4 on: January 23, 2018, 04:14:41 PM »
I have macros...
These will only shade the active window, but the shading will persist.

'Shademode.d3m
sys(72)=1 'Enable graphics accelleration
sys(2)=2  'Flatshade mode
>regenerate
{
}
end

'smshade.d3m
'Smooth shading
sys(72)=1 'Enable graphics accelleration
sys(2)=3  'smooth shade mode
>regenerate
{
}
end

I would do your problem this way"
Make sure the upper and lower faces were proper (and separate) grids.
Extrude the upper face down past the lower face.
Extrude the lower face up past the upper face.
Use SolidIntersect to create your net wing volume.

Lar

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Re: WallThickness and 3D Printing
« Reply #5 on: January 23, 2018, 04:21:28 PM »

Does 2018 have better graphics?
One simple but substantial improvement to the graphics in dc2018 is 'mixed mode' shading, which is shading with outlines (it's one of the options under OpenGL shading).


Lar
...One issue with mixed mode shading is the outlines seem to disappear when viewing from the rear, or they are much softer or maybe the entity's color rather than black.
...One nice thing is a mixed mode hi-res PDF print is pretty impressive (same as above from rear, though).

Dr PR

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Re: WallThickness and 3D Printing
« Reply #6 on: January 23, 2018, 11:49:50 PM »
Walt,

There really isn't much that helps viewing in wireframe views. The more lines in the drawing the more cluttered and hard to view it gets.

The best thing is to use a lot of layers so you can disable viewing some of the objects not necessary for the work you are doing at any particular time.

Like Rob S said, you can try to work in OpenGL shaded mode. Quick shading has only shaded surfaces/facets with no smoothing. Gouraud shading produces smooth surface views. You can rotate the view without losing the shading.

Phil
DesignCAD user since 1987