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Website Update: New Volume Calculation


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I thought that hollow objects already were calculated as solid? Also I can't wait for this update! It will allow so many ideas to be made without having to boolean complex objects.
#1 Mike Armbrust on 2010-07-13 19:50 (Reply)
Does the overlapping calculation have any effect on pieces that overlap themselves? Such as a continuous, solid tube which curves back on itself. I presume that the new overlap calculation is merging distinct pieces and won't detect this case?
#2 fracai on 2010-07-13 21:32 (Reply)
Bravo!!!

-Whystler
#3 T. Shawn Johnson on 2010-07-13 23:10 (Reply)
Do holes have to be part of the mesh or can they be built from multiple meshes with different normal orientation? Take the top image, left side, and imagine one of the shells is reversed. Will it print and be billed as a square with one missing corner? As a full square? As the two squares joined like in the right side?
#4 Stannum on 2010-07-14 00:54 (Reply)
That is a hard question. It depends on a number of factors like the surface area of the shell / mesh.

But if you take the example from above the mesh with the inverted normals will get fixed and you will get two joined cubes.
#4.1 Robert Schouwenburg on 2010-07-14 09:35 (Reply)
I can see how this helps people but for me this is bad news. I create geometrical models with flat faces, that cannot have holes in them. I use the hollow object "trick" as described above to keep the price of my models acceptable.
Ok so maybe it is possible to create tiny, hopefully invisible, holes in my models. I don't know. But my models will look the same, cost the same, print the same. So this brings me nothing, only extra work.
Anyway in the sentence "This can be easily avoided by creating a small hole in the object's wall" I'd leave out the "easily".
Maybe it is possible to leave the current volume calculation and the hollow object "trick" available as an option when uploading models?
#5 Mark Holtkamp on 2010-07-14 11:02 (Reply)
I like that., because it makes designing easier.
Maybe you should consider a button for redoing the calculation of an item for users which want to use the new algorithm.
Can also be achieved by uploading a new version (the latest design) once more.,
#6 Andreas Woody64 on 2010-07-14 20:28 (Reply)
I just uploaded a model and either this new system is amazing or it doesn't check for manifold errors. My model externally was correct but it had horrible errors in Blender. If the new system was able to just fix it up that's amazing!
#7 Mike Armbrust on 2010-07-14 22:26 (Reply)
Hi Mike,

I suspect your model had a visit from our Mesh Medic:

http://www.shapeways.com/blog/archives/398-Mesh-Medic-automatic-3D-printing-file-repair.html

Bart
#7.1 Bart Veldhuizen on 2010-07-15 08:43 (Reply)
I agree that adding holes to meshes isn't always easy for hollow parts...
I really wish there was an option to keep things hollow...
#8 Derek Bosch on 2010-07-15 15:23 (Reply)
By now I used excusively OpenSCAD for my models which does the whole boolean merging for me, so this update does not mean any direct price reduction for me.

Regarding the closed space trick:

I recall to have seen a video where someone suggests it.
I think it was about leaving the support material in a puzzle consisting out of the detail material.
But is it really ok to do that? Especially in the other materials I wonder.
I mean the supporting material there is the building material itself => same cost for you.

So, suggesting cheating but making it harder at the same time ... clever.
#9 lukas (Homepage) on 2010-07-15 16:38 (Reply)
There are two costs to the process: 1) the cost of the material, an 2) the cost of time/energy to run the laser. I would hazard a guess that the cost of the material is smaller than the cost of running the laser.. that's why you can get away with this 'support material' concept and not hurt their costs much.
#9.1 Stony Smith on 2010-07-19 04:16 (Reply)
But the time needed for a specific print should also be proportional to the volume (if the entire printer volume is filled up every time).
#9.1.1 lukas on 2010-07-19 11:05 (Reply)
For the detail materials, the support material has to be discarded anyways. For SLS, the tiny amount of material that can be trapped is not worth a lot compared to what is wasted to begin with (they can only recycle x% of powder or the prints will turn out bad).
If a part is hollow doesn't affect print times by much: for SLS, the lasers scan time is very small compared to the time laying down a new layer takes. For other printers, it doesn't matter whether you're depositing support or build material.
A big part of the cost comes from the people operating the printers and cleaning the parts. For them, having an enclosed hollow is probably better than having a cleanable one because it takes less work to clean.
#9.1.2 Tom van der Zanden (Homepage) on 2010-07-21 10:24 (Reply)
I'm glad to hear this because my models had up to 50% overlappings.
#10 Baumann Eduard on 2010-07-15 16:53 (Reply)

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