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# water tight ?

water tight ? [message #53128] Sat, 25 August 2012 17:43 UTC
hi

i tried so many times to upload .stl file to cubify account, but it said: "Model is not 3D Printable because it is not water tight."
http://cubify.com/account/

is anyone here know what is mean?
and, how to fix this?

Thanks

Bertus
Re: water tight ? [message #53133 is a reply to message #53128 ] Sat, 25 August 2012 21:05 UTC
Watertight is a simpler term for Manifold.(Basically a 3 dimensional mesh which has a well defined surface area and a volume. ) Watertight is just the idea if you submerged it in water, the water would only contact 1 surface of any face of the model, not both sides of any face.
So with that reasoning, a plane object would have a surface area , but not a volume, so not watertight(non manifold). If the plane was extruded, forming a cube,it would have a volume now and a surface area, thus watertight.

As for our submerged object a well defined surface is when any face on a surface exposed to the water, its face normals should be pointing in the direction its surface is in contact with the water.

Sorry for this simplified explanation. The proper mathematical explanation gives me a headache. For a good little program that can fix several mesh errors, download netfabb basic. But nothing beats proper modelling techniques, including checking normals and manifold several times in its creation process.

Keith

Have any questions regarding Blender, and need fast answers, you are always welcome at the IRC Server Freenode, channel #blender. As a bonus, several there have experience in modelling for 3D prints.

Keith
Re: water tight ? [message #53139 is a reply to message #53133 ] Sun, 26 August 2012 01:14 UTC
Thanks to great explanation Keith
But, i'm still confusing
Is the water-tight criteria different according to the method of 3D printing?
I have many models that succesful uploaded to shapeways,
But they can't be printed in cubify (cubify.com),
Can you check the problem in there?

Thanks

Bertus
Re: water tight ? [message #53142 is a reply to message #53139 ] Sun, 26 August 2012 07:30 UTC
Shapeways has an automated system for fixing errors in your model. It sounds like Cubify doesn't, so you'll have to fix the model before uploading there. That's one reason why Shapeways rocks

BTW, nobody here can open your Cubify account from the link you posted as it takes your username and password to see your account (and don't ever post them publicly or share with a stranger!)

[Updated on: Sun, 26 August 2012 07:30 UTC]

Pssst! I wrote a book to help you quickly get your Sketchup models ready for printing. Click here to get it on Amazon
Re: water tight ? [message #53146 is a reply to message #53142 ] Sun, 26 August 2012 09:45 UTC
Hey denali3ddesign,

Good to hear that you like our automated system
However, fixing it here before uploading there will not really work, if you download the uploaded STL from our website, you will receive the "orginal" model, not the one which has been repaired!

Mitch
Re: water tight ? [message #53149 is a reply to message #53146 ] Sun, 26 August 2012 10:01 UTC
Mitch,

Sorry I wasn't clear - I meant that Bertus will have to fix the model with something like Netfabb, as mentioned by Keith above.

Cheers!

Pssst! I wrote a book to help you quickly get your Sketchup models ready for printing. Click here to get it on Amazon
Re: water tight ? [message #53150 is a reply to message #53149 ] Sun, 26 August 2012 10:06 UTC
Ah sorry, my apologies
Re: water tight ? [message #53152 is a reply to message #53150 ] Sun, 26 August 2012 10:10 UTC
No worries, Mitch.

Pssst! I wrote a book to help you quickly get your Sketchup models ready for printing. Click here to get it on Amazon
Re: water tight ? [message #53255 is a reply to message #53152 ] Tue, 28 August 2012 09:14 UTC
so, can you check my models?

http://www.shapeways.com/model/677537/yggdrazil.html

i've checked it with netFabb but no error mesh can be found . . .

• Attachment: Untitled.jpg

Re: water tight ? [message #53281 is a reply to message #53255 ] Tue, 28 August 2012 22:33 UTC
There were a few faults still in your model. I have repaired it in another program and emailed it by PM.
Re: water tight ? [message #53320 is a reply to message #53281 ] Wed, 29 August 2012 18:34 UTC
When you open your file in Netfabb, everything seems OK. If you then do a repair, you will see that it has a few anomalies, i.e. degenerated faces. You will see them by zooming in, they are lines coloured orange. You would think by doing an automatic repair it would fix the problem. Well it does not. If you try to export your model you will see the problems. If you try to repair in this window the numbers in the file quality box get worse. So netfabb sometimes can not repair it.
When you upload to Shapeways, they do an automatic check and if it is repairable they will repair it. That is why it uploaded fine to Shapeways.
I repaired the file in Meshlab. Just by using one of the filters. I then exported from there and put it back in Netfabb, then exported again to get the green tick.
Do not take Netfabb as Gospel. If it looks fine. I still do a repair and try to export it. If you get the green tick then everything should be OK.

• Attachment: meshlabb.png