Newbie: How to design a part without voids ?

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Newbie: How to design a part without voids ?

stressless
I sliced up a few of my parts (just to see) and noticed that they are full of voids decided at printing time (slicer) or when exporting to STL. The position of these voids are not visible in Openscad.
 
I now need to make a simple circular part that I will have to drill radially and tap to receive an M3 screw. How do I know that I will not be drilling into a void ? In other terms, i there a way to insure that a certain portion of the part will be voidless ? Can Openscad reveal these voids at design time ?

Thanks in advance for any help.
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Re: Newbie: How to design a part without voids ?

jon_bondy
The voids are there because you (or someone/thing else) specified an
infill percentage < 100.  I typically use 20% for most parts, because
they are strong enough at 20%, and because it uses less material and
prints more quickly.

As to drill and tap, I include holes in my designs where I need to tap.  
The slicers allow you to specify how many "perimeters" to print
(external layers), so a small hole suddenly is surrounded with solid
material, even if the majority of the part only has 20% infill.  I would
recommend designing your holes into your part.

Jon


On 12/6/2016 6:26 AM, stressless wrote:

> I sliced up a few of my parts (just to see) and noticed that they are full of
> voids decided at printing time (slicer) or when exporting to STL. The
> position of these voids are not visible in Openscad.
>  
> I now need to make a simple circular part that I will have to drill radially
> and tap to receive an M3 screw. How do I know that I will not be drilling
> into a void ? In other terms, i there a way to insure that a certain portion
> of the part will be voidless ? Can Openscad reveal these voids at design
> time ?
>
> Thanks in advance for any help.
>
>
>
> --
> View this message in context: http://forum.openscad.org/Newbie-How-to-design-a-part-without-voids-tp19488.html
> Sent from the OpenSCAD mailing list archive at Nabble.com.
>
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Re: Newbie: How to design a part without voids ?

MichaelAtOz
Administrator
In reply to this post by stressless
.
stressless wrote
I sliced up a few of my parts (just to see) and noticed that they are full of voids decided at printing time (slicer) or when exporting to STL. The position of these voids are not visible in Openscad.
 
I now need to make a simple circular part that I will have to drill radially and tap to receive an M3 screw. How do I know that I will not be drilling into a void ? In other terms, i there a way to insure that a certain portion of the part will be voidless ? Can Openscad reveal these voids at design time ?

Thanks in advance for any help.
When you say "my parts" do you mean things constructed by OpenSCAD code, or .STL etc you import() into OpenSCAD?

In the former, you create the voids, in the latter they are there as designed.

I think the answer is NO, not by default.

One option is to use projection(cut=true) with a translate in an animation, it will let you see through the model in slices

I'm not sure what you mean by "full of voids decided at printing time (slicer) ".

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Re: Newbie: How to design a part without voids ?

stressless
In reply to this post by jon_bondy
Thanks Jon. If the infill percentage is to be set on the printer, I cannot do anything about it because I don't own a printer. I order my parts at a 3rd party's. If it can be specified within Openscad, please instruct me.

As for the drill and tap, I will follow your advice and design holes into my parts

Dan
* * * * * *

jon_bondy wrote
The voids are there because you (or someone/thing else) specified an
infill percentage < 100.  I typically use 20% for most parts, because
they are strong enough at 20%, and because it uses less material and
prints more quickly.

As to drill and tap, I include holes in my designs where I need to tap.  
The slicers allow you to specify how many "perimeters" to print
(external layers), so a small hole suddenly is surrounded with solid
material, even if the majority of the part only has 20% infill.  I would
recommend designing your holes into your part.

Jon


On 12/6/2016 6:26 AM, stressless wrote:
> I sliced up a few of my parts (just to see) and noticed that they are full of
> voids decided at printing time (slicer) or when exporting to STL. The
> position of these voids are not visible in Openscad.
>  
> I now need to make a simple circular part that I will have to drill radially
> and tap to receive an M3 screw. How do I know that I will not be drilling
> into a void ? In other terms, i there a way to insure that a certain portion
> of the part will be voidless ? Can Openscad reveal these voids at design
> time ?
>
> Thanks in advance for any help.
>
>
>
> --
> View this message in context: http://forum.openscad.org/Newbie-How-to-design-a-part-without-voids-tp19488.html
> Sent from the OpenSCAD mailing list archive at Nabble.com.
>
> _______________________________________________
> OpenSCAD mailing list
> [hidden email]
> http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2016.0.7924 / Virus Database: 4664/13542 - Release Date: 12/06/16
>
>


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Re: Newbie: How to design a part without voids ?

stressless
In reply to this post by MichaelAtOz
Thanks MichaelAtOz,
I actually cut up real printed parts that were designed with Openscad to see what was "inside". And no, I did not design these voids. When I say "voids", I mean empty spaces within the parts where no material was deposited. This probably has to do with the infill factor mentioned by Jon (above message).

When I design parts in Openscad, I just see a solid fully filled piece (unless I difference() ). When I receive the part from my 3rd party printer, the part has a large number of non-designed voids in between the outer walls. That's fine with me because the part is strong enough but it's a bother if, in my case, I need to drill and tap a hole.

I just wanted to know if it is possible to see and control the number and position of these voids at design time. They come as a surprise when I receive the part from my remote printer.
Sorry for not being clear in my first message.

* * * * * *
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Re: Newbie: How to design a part without voids ?

Alan Cox
On Tue, 6 Dec 2016 11:18:35 -0700 (MST)
stressless <[hidden email]> wrote:

> Thanks MichaelAtOz,
> I actually cut up real printed parts that were designed with Openscad to see
> what was "inside". And no, I did not design these voids. When I say "voids",
> I mean empty spaces within the parts where no material was deposited. This
> probably has to do with the infill factor mentioned by Jon (above message).
>
> When I design parts in Openscad, I just see a solid fully filled piece
> (unless I difference() ). When I receive the part from my 3rd party printer,
> the part has a large number of non-designed voids in between the outer
> walls. That's fine with me because the part is strong enough but it's a
> bother if, in my case, I need to drill and tap a hole.
>
> I just wanted to know if it is possible to see and control the number and
> position of these voids at design time.

Talk to your printer. If there are voids in your product and not in your
STL then they are adding them (which is normal for a lot of 3D companies,
generally the right thing to do, but a disaster if you are are doing
anything structural).

Alan

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Re: Newbie: How to design a part without voids ?

Stefan Peter
In reply to this post by stressless
Hi Dan

On 06.12.2016 18:56, stressless wrote:
> Thanks Jon. If the infill percentage is to be set on the printer, I cannot do
> anything about it because I don't own a printer. I order my parts at a 3rd
> party's. If it can be specified within Openscad, please instruct me.

What 3rd party especially? You may be able to supply a model describing
the general shape of your model and one describing the areas that need
to be filled 100%. It depends on the sclicer used by the 3rd party and
the effort they want to put into the job.

With kind regards

Stefan Peter

--
There is no system but GNU, and Linux is one of its kernels.

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Re: Newbie: How to design a part without voids ?

Ronaldo
In reply to this post by Alan Cox
stressless,

It is usual to specify infill and perimeters values when you order a 3D printing. If you don't they set them to standard values. Talk to them: 20% is fine for non-structural parts, as jon wrote, and 3 to 4 perimeters is enough if you will tap some part hole.

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Re: Newbie: How to design a part without voids ?

Joseph Lenox
Slic3r's Modifier meshes will let you set the infill to 100% selectively, fyi. I have a pull request open to generate those meshes on the fly and position them in Slic3r.

--Joseph Lenox

On Tue, Dec 6, 2016 at 12:55 PM, Ronaldo Persiano <[hidden email]> wrote:
stressless,

It is usual to specify infill and perimeters values when you order a 3D printing. If you don't they set them to standard values. Talk to them: 20% is fine for non-structural parts, as jon wrote, and 3 to 4 perimeters is enough if you will tap some part hole.

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Re: Newbie: How to design a part without voids ?

stressless
Thanks to all for your valuable replies.
I feel a bit smarter now and will put the advice to good use.
Regards,
Dan
* * * * * * *