Wednesday, August 1, 2012

1 million polygons served...or less.

So, today I learned a little bit about the file size limits on shapeways.

As an Autodesk inventor user, typically to export for shapeways i would go to...
Print->Send to 3d print service.
I check the unit of measure to make sure i'm sending the right size, and set the resolution to "High".
Click "Okay", and save the resulting STL file.

Up until today, I had always done smaller single object files.
Today I wanted make a multipart STL that was a batch of objects connected with sprues so that it could be processed at one items. This is what sent my file over the limit, and this was new territory for me.

At my current employer, all our files sit happily on the server and they only get opened in inventor.
So, if I can make it in inventor, then everything is a-okay. I don't have to worry about file formats or size or resolution or anything at all really.

In the 2D world of printing, I'm very comfortable. So much so that I authored a new set of guidelines for my previous employer, who had as many as 20 designers pumping out files much larger than they needed to be. But, that's all in the past. Here in the future, in the world of 3D, I've heard of some formats and I've heard of some software, but I have little experience. So, it looked like it might be time to do some research.
Well, like a typical guy, i knew enough to be dangerous, so I opted to not read the instructions and just started trying things.
The results were good. I didn't have to stray far from my old ways to do what I needed. The 2d world taught me that I can reduce file size if I sacrifice quality. So, the first thing I tried was reducing the resolution of the STL from high to medium. Out of curiosity i decided to press the print preview button.
Which to my delight showed me a preview of the resulting mesh, the resulting file size, as well as the polygon count. It still looked great, the facets were well above the level of detail i needed, and my file size was below the minimum now too. So i'm good to go now. Right?

WRONG... I was over the maximum polygon count for shapeways. The max polygon count is 1 million triangles. Lucky for us, inventor tells us in the preview window exactly how many wer're using right there in the print preview window. So... i tried again. This time i chose a custom resolution and set the "surface deviation" to something slightly higher. My polygon count went down even more. One more tweak to the surface deviation and i was good to go. My file was under the max file size, had less than 1 million polygons and still was an acceptable looking mesh. Now, what i need to do is get a prototype made at this resolution.
I'd like to see how the printer interprets this new resolution when it breaks the mesh down into layers of printed material.

Thanks for reading!

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