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Negative space and building clean 3d models ??

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Morning guys.

My question is, now that I have my ultimaker pretty well set and its printing models from thingiverse with a level of ease.

The next step for my company is to start printing our in house models !

There are sources of 3d models coming out of our company, archicad, cinema4d and sketchup.

I have a large model that i must print and that has been created in cinema4d, i have cleaned them and then washed them through netfabb for testing.

My strange problem lies, when the model is brough into cura4 and sliced, all intersections between separate solid bodies, become negative space in the print model and when cura prints the models, we get large openings in the corner walls and some times even in the middle of walls ?? very strange stuff.

I guess my question is, what are the guys doing on thingiverse to produce these beautiful clean building models and how ??

I even started to duplicate some of our simple building components yesterday evening in sketchup.. exact same problem, all intersection bodies, box window in roof for example, gave negative space and then caused only murder in the final print model.......

Please help if you can guys.

This problem has to be solves fast,,, my job kinda hangs on the success of this technology for our company...... yikes....

Thanks a million.

Ian :D

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here to start the imagination going.

here is my cinema model very simple structure first created in archicad and imported later into cinema.

One problem is, that archicad builds roofs for example, like a real roof solíd with a inner and outer face and with lots of dirty angles intersection other roof members. that makes the model not so water tight.

But holy god, if netfabb cant lock up a simple model like this, then im at nothing here...

Ian :)

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I'm not sure what archicad is doing. But I've checked out the model.

I removed all houses except for 1, so I could take a better look at it, most houses seem to have the same errors.

It seems that Archicad isn't very accurate in generating vertexes (3D points) as the corners don't all seem connected. Also there are also duplicate faces in each roof. If I use 3D studio max "vertex weld" feature on 0.1mm, then the model is fixed. This will merge all vertexes which are within 0.1mm of each other. After that I needed to remove the duplicate faces from the roof.

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I had a discussion with Daid on exactly this topic a few days ago involving circles and triangles. it sounds like Daid has already found a solution to your problem, but it's worth being aware that if your model consists of two solids that intersect, some packages export stl that will look correct on screen but slice to give inside out prints (or negative space as you called it).

the solution, in my case, was to use booleans to ensure that no individual parts of the model overlapped. I could also have union'd them all into a single part for the same effect.

netfabb was pretty useless in this case - it just tried to close all the holes and messed things up. what i really wanted was a 'make my model the way it looks on screen' button. which doesn't exist.

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ok thanks guys.

I took Daids advice and this is what I did.

Our office sadly has only Cinema4D, and of coure Cinema doesnt have this welt vertex option..... its a weird world we live in ?

So, i took the house model, created a massive big box over the house model, then positioned the box to sit on the 00 horizon with the house model.

Then using Bolean tool, i subtracted the houses from the solid box. checked quality to normal and got as a result a box of the negative form of my building inside.

Then I pan caked the model data from the Bolean Box and the house model together as one.

Picked the 4 top corner vertex of the box and pulled them down to the 00 level.

So then I had a mask of the whole structure that looked good.

Brought it into netfabb for a quick clean, still double roof data for some reason.

But decided to carry on and see.

ran the new model through cura4 gcode and BANG ! same problems again, big empthy spaces in my model.

Check out the photo below.

I thought I was being clever by using the Bolean tool to create a one part mask around every thing but some where in the system, there is still unsorted information being brought in (double roof for example)


Ian :)

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I think milkshape 3D has a vertex welding tool that you can use. It also allows for pretty low level editing of faces and stuff, so you can check out what's really in the model. It's also free to use for 30 days, and pretty cheap after that if it serves your goal.

Thanks Daid ill give it a try this evening !

Ian :-)

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from simple experience of printing arch models in 1 to 500 scale, i know a lot of details will never been printed or even seen my people.

so my idea is !! i take our complex horrible archicad model, import it as a xref into..... sketchup maybe, then create simple boxes and objects to symbolise the structure, for normal surrounding buildings for example, that would mean a box as the house structure, another box to represent the door and then a roof shape.

For the surroundings buildings that would be enough.

So 3d printing might not like archicad 3d data ( i guess 3d generated information from a excell spreadsheet and then rounded off numbers adds up to a pritty ugly print model) so the best strategy, find a free program that will mesh over the surface of my models OR quickly duplicate my model new and fresh in a stable format that gives me no crazy minus intersection spaces.....

what do you think guys ?

Ian :)

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