Road to rep-rap modeling


Well i decided to go for a mendel rep-rap, out of a creationist hobby or as in second life I’m a builder, and in real an artist.
Now it appears to me that a few people did this before, use blender for creating 3d objects.

As I would like to get also into this and learn a bit from it, before i assemble the 3d printer.
I have some question for those who are into it.

  • What is the road of format conversions to a final format so that a mendl printer can print it ?
    What software did you use besides blender.
  • How do you deal with metrics (so 10 cm in blender is exact 10 cm in your final product)
    In general how do you change or set seizes of lines so that
    after you made something can correct something to a certain distance in blender ?
  • How do you strengthen, or optimize shapes so final products become less fragile

I also wonder since I’ve seen how blender can interact with video (one of the new features) if maybe in the near future blender will be able to scan objects for 3d usage, i think the math involved in that video scanning is a great starting point for such. As it does already recognize 3d info from a 2d camera movie.

As I know none of 3d packages handle STL export and G-code well. Most guys in Polish reprap community prefer Netfabb for STL optimization.

  1. Reprap software uses models in the stl format. Blender has an exporter for that format, so no problem. Then you’ll have to use a “slicer” to, well, “slice” the model into layers and generate gcode for the host software that sends the commands to your machine. Common slicers are Slic3r (easy to use) and skeinforge (tougher learning curve, more accurate, but slower). There are others (Kisslicer, Cura, etc)
  2. 1 Blender unit = 1mm.
  3. I guess this comes with experience. My first models were humorously over-built. I print in PLA, and I’ve had no problems making my models strong enough for my needs. It’s more of a challenge to make something that prints well but isn’t wasteful of plastic. Download models from and learn from the work of others. I posted a model a few days ago that is very complicated and 100% Blender (

Have fun! It can be frustrating at times getting a machine up and running, but once you’ve got it all sorted, a 3D printer opens many opportunities for a “maker”.

(your scanner question is beyond my expertise).

  1. 1 Blender unit = 1mm.

Not sure where you got this (some exporter default?) but in general one BU is considered 1 meter for the areas where it is relevant (physics simulation, for instance).
You can also specifically set units in preferences to help with modeling (but I’m not sure whether simulation will honor that)

In general, changing the scale of the entire model will likely be an option in an exporter, otherwise you can just scale the objects in blender by a given ratio manually.

P.S: the word creationist may not mean what you expect, I think the word you are looking for is ‘creative’

@Zalamander - I was addressing his question regarding reprap software, not physics sim, etc. As reprap software interprets them, STLs from Blender are scaled such that 1 Blender unit = 1mm. It’s that simple.

@Zalamander - I was addressing his question regarding reprap software, not physics sim, etc. As reprap software interprets them, STLs from Blender are scaled such that 1 Blender unit = 1mm. It’s that simple.

So the startup cube is 1 mm ?.
your model looks great is it an egg alarm perhaps ?.. would be fun as alarm clock

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As built, it’s just a regular clock using a quartz clock movement which can be bought from many sources, or taken out of most cheap clocks. But since this is a do-it-yourself kind of thing, you can make it what you want. There’s a lot of room inside the body for stuff.

Regarding Monio’s comment - I’ve had no trouble with STLs exported from Blender. That’s assuming the work was done following good modeling practices. The object has to be manifold, face normals consistent, the proper scale, mesh and object’s origin near 0,0,0. Since you control the topology in Blender, unlike with solid modeling software, any problems are your own fault. Solid modeling programs sometimes export topology that make an old mesher like me shudder, and those are the files that have to be run through the software Monio mentions.

Is it that hard to slice a model and use the slices for creating a G-code ?? i would have thought this wouldnt be too hard.
Rendering seams much more complex to me