Missing support in software

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svid123
Posts: 14
Joined: Sat Feb 25, 2012 5:26 am

Missing support in software

Post by svid123 » Sat Feb 25, 2012 5:54 am

Hello,

I try to print a simple two solid halves of small rounded box with a step on the adjacent edge.
So it seems that depending on the edge of cap (or may be polygon count in model), I came out that it's impossible to print second cap, the software doesn't place support and don't print the rest of the model.
It prints well in case of cap's edge #1 (in picture below). And if the edge like #2 it print with wrong support.
The support angle (as well as others settings) doesn't affect this error. It's always a hole in the support in the second case.

Sometimes printing software displays error message: "Error: a; there are not model & support at height 0.2~"
screen.jpg
screen.jpg (102.89 KiB) Viewed 10208 times
first.zip
First box half STL
(195.12 KiB) Downloaded 344 times
second.zip
Second box half STL
(177.4 KiB) Downloaded 431 times

Madox
Posts: 441
Joined: Wed Sep 15, 2010 1:30 pm
Location: Sydney
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Re: Missing support in software

Post by Madox » Sat Feb 25, 2012 9:28 am

Hi,

I'm not sure what the problem you described is. I have not downloaded your STL, but I suspect you might attempting to print thin walls.

The slicing performed depends on the 'Fine'/'Normal'/'Fast' setting, and as a general rule, any feature or wall smaller than 1mm may not slice correctly and will be ignored. i.e. any wall less than 1mm might turn into a 'hole'.

I hope this helps you.

[My slightly more advanced rule is 0.8mm on fine...this number goes up when using normal/fast]

Marcus
Posts: 526
Joined: Thu Nov 04, 2010 9:58 pm
Location: Germany

Re: Missing support in software

Post by Marcus » Sat Feb 25, 2012 10:40 am

The second half is inverted (inside out/negative volume; showing in the PP3DP software as red, in Sketchup as blue, in Netfabb red instead of green, in others like Lightwave "backsides" are transparent so the object has a bit of an x-ray feel to it).
In Nettfabb, rightclick object ->repair part, Actions/Select shells with negative Volume, rightclick object->Reverse selected triangles
(Using a older german version, so the names/menu item locations may be different).

In some applications such as Sketchup the inversion happens when flipping a grouped object by scaling it negative.

Quickly examining the thing shows that the walls are thicker then 1mm, the edge thicker then 0.8mm, so it should print- at least better then that ;-)

The print-unsolid function of the PP3DP software only helps a litle with inverted/negative volume objects and the results differ from part to part. Other printing software like some for the Reprap does not care if it is inside out or not...

svid123
Posts: 14
Joined: Sat Feb 25, 2012 5:26 am

Re: Missing support in software

Post by svid123 » Sat Feb 25, 2012 11:46 am

Marcus wrote:The second half is inverted (inside out/negative volume; showing in the PP3DP software as red, in Sketchup as blue, in Netfabb red instead of green, in others like Lightwave "backsides" are transparent so the object has a bit of an x-ray feel to it).
In Nettfabb, rightclick object ->repair part, Actions/Select shells with negative Volume, rightclick object->Reverse selected triangles
(Using a older german version, so the names/menu item locations may be different).
That's a bit strange (I've checked normals before export to STL). However, I'll try to print with "inverted" normals.
Thanks.

Marcus
Posts: 526
Joined: Thu Nov 04, 2010 9:58 pm
Location: Germany

Re: Missing support in software

Post by Marcus » Sat Feb 25, 2012 12:16 pm

As I am just a Sketchup user (well, and Lightwave, but not for CAD), and I do not know what software you use, I can only tell you what I learned in the last year.
The STL plugin will take a perfectly fine orientated group and export it inverted, if it has been scaled by -1 (flipped).
If I break it appart first (perhaps group it again) and export the STL, it works fine.
Perhaps it is a similar issue...
Otherwise as long as the object is watertight selecting negative volumes with netfabb and inverting is a quick workarround.

Hope this solves your problem! Keep us posted :-)

svid123
Posts: 14
Joined: Sat Feb 25, 2012 5:26 am

Re: Missing support in software

Post by svid123 » Sat Feb 25, 2012 4:10 pm

Ok, flipped normals and it printed correctly.
The cap is exported from 3DSMax (from Editable Mesh object, converted from NURBS surface). Both caps have correct normals (checked) in 3DSMax and there was no any flip/mirror operation on them.
Probably it's 3DSMax STL export plugin bug.

Thanks for help

PS. It would be nice to display back faces with black color (or not to display at all), rather than in red color, which confusing with selection of object.

Marcus
Posts: 526
Joined: Thu Nov 04, 2010 9:58 pm
Location: Germany

Re: Missing support in software

Post by Marcus » Sat Feb 25, 2012 4:59 pm

Great!
As long as the export plugin inverts the complete part and not just some random areas it should be easy to fix such problems. Perhaps there's allready a big report or work arround online?

What I did is to go to VIEW, COLORS and used a light blue as selection color, otherwise try posting in the most recent update thread to request it :-)

pleppik
Posts: 336
Joined: Sun Dec 11, 2011 2:14 pm

Re: Missing support in software

Post by pleppik » Sat Feb 25, 2012 9:23 pm

There is a free online service which will fix common problems with STL files like inverted normals, holes, etc.:

http://cloud.netfabb.com/

It makes a HUGE difference--for some programs (like SketchUp) I run the STL through every time. Some programs just seem to produce bad STL.

Marcus
Posts: 526
Joined: Thu Nov 04, 2010 9:58 pm
Location: Germany

Re: Missing support in software

Post by Marcus » Sun Feb 26, 2012 12:13 pm

Except the negative volumes which can be fixed by breaking and regrouping I never had issues in Sketchup... I guess I am a bit old fashioned, but I don't like doing everything "in the cloud" :-)

pleppik
Posts: 336
Joined: Sun Dec 11, 2011 2:14 pm

Re: Missing support in software

Post by pleppik » Sun Feb 26, 2012 1:53 pm

Marcus wrote:Except the negative volumes which can be fixed by breaking and regrouping I never had issues in Sketchup... I guess I am a bit old fashioned, but I don't like doing everything "in the cloud" :-)
They also have free desktop software which does the same thing, though I've found the desktop software more of a nuisance to use--it doesn't have the handy "fix everything broken" function of the web service.

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