Blender Tips for modeling engineering models

1. Use layers to organize the different objects.
In object mode, space -> Object -> move to layer will move any selected objects to the specified layer.
number keys 1-9 (not keypad) will show the specific layer.
shift + number key 1-9 will toggle layer visibility.

2. If you are doing CSG modeling:
- Create multiple objects, each one a set that does not intersect itself.
- You can include non-closed shapes, I.E, three or four cylinders, in the same shape.
- It is easier use intersection by inverting the normals on the object that is to be cut out of another object, rather than try to remember which order you have to select the objects for a difference operation.
- When unioning objects, make sure you have some overlap to ensure proper boolean operation.
- Be patient. Intersect and Union appear to take time if the models have lots of detail.

Example, for the 'clamp' for the extruder, I created 5 mesh objects:
A. one large rectangular box for the main body.
B. one rectangular box for the 'tab'
C. one rectangular box for the raised area around one hole.
D. rectangular boxes for the boxy areas to cut out of the body, with inverted normals, so intersection will cut out interiors.
E. cylinders for cylindrical holes, with inverted normals, so intersection will cut out interiors.

Using boolean operations, I easily created the final object:
E. Union A and B to get a box with a tab.
F. Union E and C to get final rough shape without holes.
G. Intersect F and D to get shape with rectangular holes and cutouts.
H. Intersect G and E for final shape.

- keep intermediate meshes, move them to a different layer to hide them. They come in use if you make mistakes and have to reperform some of the boolean operations.

3. toggle "edge length" in the "mesh tools 1" window on the editing panel to get lengths (in mm). Create temporary edges between verticies if necessary. Toggle edge angles to get angles between edges (located in the same tool window).

4. Use a 2D tool to create rough pictures for one or two faces. Put them as background images to guide modeling.

5. Make use of cursor positioning and snap tools.
- view properties to set an absolute cursor position
- create 'empty' objects to mark important locations, use snap menu for cursor, objects, points, etc.
- you can snap all selected points to the closest grid displayed. Useful if you are 'freehanding' a 2D curve for fill and extrusion.

6. Bezier objects appear to work okay if you need a prism of a 2D graph.

7. There is a good web and video tutorial for CAD with blender at [www.rab3d.com] (Thanks Kaiser! This link is great -- he posted this on a comment on Forrest's blog. I learned a few new tricks watching this.)

8. There are lots of good plugin scripts at [wiki.blender.org], including some specific to CAD.

BeagleFury Wrote:
-------------------------------------------------------
> 1. Use layers to organize the different objects.
> In object mode, space -> Object -> move to
> layer will move any selected objects to the
> specified layer.
> number keys 1-9 (not keypad) will show the
> specific layer.
> shift + number key 1-9 will toggle layer
> visibility.
>
> 2. If you are doing CSG modeling:
> - Create multiple objects, each one a set that
> does not intersect itself.
> - You can include non-closed shapes, I.E,
> three or four cylinders, in the same shape.
> - It is easier use intersection by inverting
> the normals on the object that is to be cut out of
> another object, rather than try to remember which
> order you have to select the objects for a
> difference operation.
> - When unioning objects, make sure you have
> some overlap to ensure proper boolean operation.
> - Be patient. Intersect and Union appear to
> take time if the models have lots of detail.
>
> Example, for the 'clamp' for the extruder, I
> created 5 mesh objects:
> A. one large rectangular box for the main
> body.
> B. one rectangular box for the 'tab'
> C. one rectangular box for the raised area
> around one hole.
> D. rectangular boxes for the boxy areas to
> cut out of the body, with inverted normals, so
> intersection will cut out interiors.
> E. cylinders for cylindrical holes, with
> inverted normals, so intersection will cut out
> interiors.
>
> Using boolean operations, I easily created the
> final object:
> E. Union A and B to get a box with a tab.
> F. Union E and C to get final rough shape
> without holes.
> G. Intersect F and D to get shape with
> rectangular holes and cutouts.
> H. Intersect G and E for final shape.
>
> - keep intermediate meshes, move them to a
> different layer to hide them. They come in use if
> you make mistakes and have to reperform some of
> the boolean operations.
>
> 3. toggle "edge length" in the "mesh tools 1"
> window on the editing panel to get lengths (in
> mm). Create temporary edges between verticies if
> necessary. Toggle edge angles to get angles
> between edges (located in the same tool window).
>
> 4. Use a 2D tool to create rough pictures for one
> or two faces. Put them as background images to
> guide modeling.
>
> 5. Make use of cursor positioning and snap tools.
> - view properties to set an absolute cursor
> position
> - create 'empty' objects to mark important
> locations, use snap menu for cursor, objects,
> points, etc.
> - you can snap all selected points to the
> closest grid displayed. Useful if you are
> 'freehanding' a 2D curve for fill and extrusion.
>
> 6. Bezier objects appear to work okay if you need
> a prism of a 2D graph.

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