3D printing may be all the rage, or if you know someone with a CNC mill or have access to one, you may be able to build scale models of your work if you know how to adequately convert your model to .svg (or of similar appropriate file type) but what about true to scale printing blueprints of your work and transferring this to a desired media (e.g. wood, plywood) in aid for building your model? Actually, you can do this, and it certainly could also help in the path to building your 3d model even as in the case of the CNC milling process.
I have a brief tutorial in prepping your model and exporting (bitmap files) from blender which can then be used for to scale printing from your favorite photoshop editor program.
Here is my Blender object file Pedal board design
Here is my Blender object file Pedal board design
Here are the steps in working with a model in blender:
Your model needs to be adequately ready from 2 dimensional projection rendering. This means that when you render parts of the model that you are able to align the planar viewport to an orthogonal view relative to its general parts geometry. For instance, if you were rendering the sides of a box, you'd select each side of the box and project at an orthogonal angle relative to the face. This gets more complicated, however, if your geometry (even being linear) has skew angles relative to the customary 3 dimensional axis. In this case, each part of your 3 D model object should be broken down into object components that share a self similarity in terms of object geometry and its local or normal coordinate axis. Good design practice in blender should allow you to select either groups of vertices or where the design is delineated at least as a separate object that is part of the overall 3D design.
Once having the model ready as stated above, with components of the model that are neither orthogonal to one of the 3 Dimensional planes (and likely given at skew angle for orthogonal projection view) means you can as I have found: Duplicate this component object (Shift + D) and then translate it to some position where it is not mixed in with the existing components 'assembled' model overall.
Now in '3D View' if you select under 'Transform Orientation' > 'Normal' if the overall object's Normal coordinate axis matches that of 'Global' then you'll need to assign and record a Tranform Orientation object reference.
To do this, having selected the duplicated component object, go into 'Edit Mode' and then select one of the representing faces of the object (that the viewport plane will be orthogonal to) and then under Transform Orientations in the Properties box under 3D view, select the '+' button.
Enter a name in the 3D Tool Shelf (left side of the 3D view...if it is not opened toggle View > ToolShelf ) for the given Transform Orientation. For instance, my Transform Orientation named 'a' is shown.
Now the Transform Orientation named 'a' is applied to the object overall if go back into 'Object' mode.
This is important since this will allow us to transform the object component's geometry to match are desired Transform Orientation which is correspondent to our Global coordinate axis. Next, select Object > Transform > Align to Transform Orientation.
Now the Component Geometry may have been further rotated in a direction we don't like.
We can remedy this by going to the 'Properties (tab) > Object tab > Transform : Rotation.
In our case, this component geometries rotation is relatively simple since it is restricted to one axis so we can change the sign of the rotation so that it is opposite of the existing value...(e.g., was 15... something degrees change this to -15.... something degrees).
There we fixed the rotation. With more complicated rotations you may have to permute sign changes to get the rotations right for flattening the component axis to a 'Global' coordinate axis. In any event we verify that the object is perpendicular to the 'Global' axis.
Next, a 'Top Down view' (numpad 7) aligns the selected and now rotated component into an orthogonal position relative our desired frame, or according to the rotation of the object relative the global axis you will want to position your view port (with a numpad 7 and then 6, 4, 8, or 2 keys) a view port position such that your view is perpendicular/orthogonal/90 degrees relative to the components projection (show picture).
Next, we will need to scale the dimensions for rendering resolution in Blender. Higher quality blueprints might use something like 300 dpi (dots/pixels per inch), in any event, you will also need to use the objects dimensions. Optimally when you are designing your object, you have set and used a real world unit system (like 'Metric' or 'Imperial') before hand when designing your model especially as it is to be translated from virtual to real world mock up. Thus you will have wanted to have enabled under the 'Properties (tab)' > 'Scene (tab)' > Units ( metric or imperial) and having chosen a scaling factor appropriate to the design level work that you are intending.
Modeling tip: I recommend before you even start modeling your 3D object setting this using the generic default cube pretending that at least one side of the cube represents the overall scale length axis of at least one axis of the object that you are working. Thus if you have a rectangular box object that is 12.5 inches you'll want to toggle into 'Edit mode' on the Cube, and enable in View > Properties (3d view) > Display : Edge info (toggled on). Now having selected an edge on the cube, toggle the scale factor (as mentioned above) until the edge length reads in the vicinity of an overall desired dimension length on at least one of the axis as prescribed.
In any event (from the tip above) you should have a reading on at least one axis of the overall length of the component object in terms of real world units (either metric or imperial). You will need to record this (favorite notepad, or google docs or someplace where it can be referenced when you need to appropriately scale the object in a favorite photo editor program, and secondly you will use this when determining the necessary rendering resolution for your bitmap file. As state 300 dpi is used for higher resolution blue printing work (likely for our purposes), so for my component at 12.5 inches width I need, 300 pixels/inch*12.5 inches = 3770 pixels on one dimension axis and probably 300 pixels/inch*5 inches = 1500 pixels on another axis .
These are entered in the Properties (tab) > Render (tab) > Dimensions > Resolution (x and y) respectively this need be correspondent appropriately with the viewport rendering capture as related to the component geometry as necessary ( in avoiding clipping or rotate the views port (using the 4 or 6 keys accordingly) so that it is 90 degrees relative to present position in remedying the problem.
Toggle the 'Toolshelf' off relative the 3D viewport (if it is shown, View>'Toolshelf') and toggle the 'Properties' off relative the 3D viewport (View > 'Properties).
Next, Shift + B allows you to frame the selected object in the viewport to desired dimension (don't forget padding your resolution for a few exta pixels in accounting for a little space for the rendering edges. This way you don't have to get the scale of the object exactly to length of one axis when rendering it.
You'll likely under the Properties (tab) > Render (tab) > Dimensions > Resolution (set the percentage to 100 percent).
Make sure you are in Orthogonal view (numpad 5) image will appear flattened relative a projective geometry view.
If all looks good, select Render > OpenGL Render Image.
Then name and save this.
You'll repeat the process mentioned above for 'skew' geometric components (in rotating them inline to global axis) by the duplication and rotation procedure indicated above, or for component geometry already setup for 2D projection viewing (with an orthogonal view port plane relative to the desired geometric projection plane...remembering to center the object in the viewport by pressing '.' then '7' for top down and then using numpad keys 4,6,8, or 2 to rotate the viewport to a given desired view and then Shift + B to scale the object in the viewport as necessary (in nearly filling at least the desired coordinate axis). Don't forget that when you have component objects that have different lengths you may want to recompute the rendering resolution x and y pixel values with scale length sizes relative to 300 dpi (for higher resolution blue print work).
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