1 Topic by seniffx

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Topic: daz/blender/meshlab units into inch/cm

I have the feeling that size does not matter when it comes to a 3d model, cuz if I wanted to print it as a tiny figure, or a foot long figure, all I would have to do is set the height I want it to print at.  But at what point do I make sure it prints at the size I want, in blender or meshlab, or the actual printer software?

In Daz I downloaded a ruler model that works great, but I have no idea how to measure something in blender, and I dont know what the units in meshlab are, I thought they might be cm, but if it was cm then the model would be way taller than what the ruler said in Daz.

2 Reply by cckens

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Re: daz/blender/meshlab units into inch/cm

You would set it at the time of slicing.  In RepetierHost, you'd set the item on the plater and then run the slice after checking the size.

When I free model, I don't worry about size because I know that I can adjust to the size of the print bed depending on what I want to use.  It's usually something that doesn't require precise measurement.

3 Reply by seniffx

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Re: daz/blender/meshlab units into inch/cm

cckens wrote:

You would set it at the time of slicing.  In RepetierHost, you'd set the item on the plater and then run the slice after checking the size.

When I free model, I don't worry about size because I know that I can adjust to the size of the print bed depending on what I want to use.  It's usually something that doesn't require precise measurement.

Most of the time when I print an object, I will need to make sure it is the perfect size, and to do that, all I will need to do is set the height to inches or at least cm.

"You would set it at the time of slicing"  I thought the act of simply exporting a model as stl format took care of the slicing, and the printer reads the stl file and prints it's slices.  Am I mistaken?

If another program in the process does the slicing, which is it.  Blender, meshlab, or the printer software?

So whatever program does the actual slicing, should I be able to simply set the height to an inch/cm value?

Some models I will need to divide into sections that my printer can print and save each section as it's own model, so for this reason I would like to set the size of the whole model in blender/meshlab before I divide it into sections to make sure that when I print all sections and assemble them together, the finished product is the height I want it to be.

If I had to, I could set the height of the model, then divide into sections, and write down the height of each individual section, then make sure each section prints at the height I wrote down for it.

4 Reply by cckens

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Re: daz/blender/meshlab units into inch/cm

seniffx wrote:

"You would set it at the time of slicing"  I thought the act of simply exporting a model as stl format took care of the slicing, and the printer reads the stl file and prints it's slices.  Am I mistaken?
If another program in the process does the slicing, which is it.  Blender, meshlab, or the printer software?
So whatever program does the actual slicing, should I be able to simply set the height to an inch/cm value?

Slicing occurs via a different software. Just being an STL file is a file format used for stereo-lithography, and not a part of the slicer.  There are many different slicers out there and it is usually personal preference that determines what is used.  Some like Slic3r, some Cura, some Pronterface.  You find what works best for you and your workflow and go with it. 

Most printing software will accept slice gCode from any slicer to print, but the ones that seem most popular are the ones that display the model on a plate that you can size to what you want (as a percentage of the original model), then slice with some integrated slicer. 

To answer the overlying question, the STL file will contain size information and can be in inches or millimeters, but since the solidoodlle bed measures 150 mm x150 mm (200 mm x 200 mm for the SD3) you tend to want to use mm.  Some software does it right, some doesn't.  CAD software is usually pretty accurate, DAZ software, not so much.  Blender with the 3d printing tools will probably do a decent job.  I don't use it so I wouldn't know.

seniffx wrote:

Some models I will need to divide into sections that my printer can print and save each section as it's own model, so for this reason I would like to set the size of the whole model in blender/meshlab before I divide it into sections to make sure that when I print all sections and assemble them together, the finished product is the height I want it to be.
If I had to, I could set the height of the model, then divide into sections, and write down the height of each individual section, then make sure each section prints at the height I wrote down for it.

So long as all the objects are the same size, you would instruct the slicing software to use the same proportion for each model.  you wouldn't need to compute sizes for each individual piece, just a percentage size that would be applied to each part.

5 Reply by adrian (edited by adrian 2013-11-09 02:24:21)

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Re: daz/blender/meshlab units into inch/cm

cckens wrote:

To answer the overlying question, the STL file will contain size information and can be in inches or millimeters, but since the solidoodlle bed measures 150 mm x150 mm (200 mm x 200 mm for the SD3) you tend to want to use mm.  Some software does it right, some doesn't.

Clarification - the STL doesn't contain any information on wether its inches or millimeters.  It simply contains units.

They are *all* measured in Units - no specific actual unit of measure, just raw 'units'... its then up to where you interpret that model as to how that program processes those units.

http://animation.about.com/od/faqs/f/Wh … mation.htm

That sort of explains it. You really need to think in just 'units' and NOT  a 'unit of measure' as it will trip you up in the future otherwise.

Anyway - Its a very important distinction - Units in 3D Space have *no* correlation to Inches or millimetres or any other 'unit of measure' - the file simply details the number of 'units'...

6 Reply by cckens

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Re: daz/blender/meshlab units into inch/cm

Thanks for the clarification, adrian!

7 Reply by foofoodog

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Re: daz/blender/meshlab units into inch/cm

If you look at the difference between two ASCII STL files exported from sketchup one as millimeters and the other as inches you will see that the mm values are simply 25.4 times the inch values. If you pull a model into RH and it appears to be about 25 times smaller than what you expect I think you can assume it was created in inches and needs to be scaled by 25.4.