This is the second entry in a series of posts discussing MakerBot & Miniatures. Check out last week’s post!
My journey to 3D modeling started at a drafting board and most of my CAD work still ends up in two dimensions on a piece of paper as a plan, section or elevation. As many of the things I model in CAD are much larger than a piece of paper, it is common practice to create full scale geometry in a CAD program, and then choose a scale in which to depict the project in a layout. When I sat down to design my first model for 3D printing, I wasn’t sure how to get started. Should I continue to create in full scale, and then scale down when I wanted to make it with my MakerBot? Or should I design directly in scale? I currently use both methods in my work, and today I’ll talk through the pros and cons of each approach.
Approach 1: Work in Full Scale Now, Scale Down Later
How it Works
As you design your CAD model, draw every measurement in full scale, or 1:1. A three foot cube will be 3’-0” x 3’-0” x 3’-0” in your drawing. When you are ready to print in 3D, import and scale within your slicing software. Or, scale a second copy of your object before leaving your CAD program. Use the process below to figure out what values to use.
Figure out the decimal value of your scale factor. In this example we’ll use 1:18.
1/18 = .056
Scale your object by .056 to convert to 1:18 scale.
If necessary, scale your object by 25.4 to switch from inches to millimeters.
Your file is ready to go! A three foot cube will be 51.2mm x 51.2mm x 51.2mm in 1:18 scale.
Note: As you design, remember the calculations we made last week to figure out the smallest features we can produce with a MakerBot in a given scale. Keep these measurements in mind as you design, so you don’t design unprintable details in your model.
The Pros & Cons
The Pros: Designing in full scale is straightforward, as every measurement in your CAD drawing corresponds to the actual measurements of an object. It’s easy to use your model in multiple ways, and shift between scales in your output.
The Cons: It’s difficult to harness the properties of your 3D printer on complicated details if you can’t subtly manipulate your CAD model. It is also easy to create too much or unprintable detail when you are working in full scale.
When Does it Make Sense to Work in Full Scale?
1. Your CAD model will be reproduced in multiple scales
If you plan to represent your object in multiple scales and mediums, create your CAD model in full scale. Use your CAD model as you typically would in your design process for 3D renderings or printed elevations. Then, reduce your model before 3D printing to an appropriate scale.
2. Your process starts with 2D elevations
If you start by drawing 2D elevations or line work, and then move to 3D, draw your elevation in full scale. The elevation can be printed in 2D in whatever scale is necessary. Editing 2D line work is often simpler than editing 3D solids, so before you translate your design into 3D, scale your elevation, and switch to metric if necessary, so you can work directly in scale. You can make subtle changes to your model for better printing, to take advantage of thread widths and layer slicing heights as you extrude your shapes to 3D.
3. Your subject matter doesn’t have complex or small features
Massing style models, with few small details, will print well in many scales. Take advantage of the simplicity of modeling in 1:1, and scale your model afterward to make in 3D.