Team: R. Siderits, M. Riad
Abstract: This project illustrates the basic CAD techniques and steps needed to design and prototype an assistive device (right angles Spoon) using a 3D printer in ABS plastic.
Step 2: Designing a Right Angle Spoon for 3D Printing
This Instructable will demonstrate some basic design steps used in 3D prototyping of a right angle spoon for 3D printing.
The 3D printer that we used was an UP!3D and the material is ABS plastic.
The take home point of this Instructable is that even with only basic knowledge of 3D design and some free CAD software, anyone can design and prototype a broad range of simple assistive devices for people with disabilities, essentially in real time and at a cost of next to nothing.
There are tens of thousands of "Parametric" files available online for download and printing on 3D printers (parametric files just save the information needed to 3D print the object, STL format example, in the real world). Places like Thingiverse.com or TED TV 3D printing are good resources to learn about how 3D printing is redefining manufacturing and distribution on a global scale.
The design process took about 90 seconds, the printing about 20 minutes and the cost was under 3 cents.
Don't worry about speed in designing with a CAD program or the particular program that you use, that comes with familiarity with your 3D CAD program. You don't have to spend as much time looking for the right buttons and you have the basic experience to know how to construct the object that you want to make. This is a fun example of those basic concepts.
Experimental Pathology Team in conjunction with the Parabiotics Research team:
Step 3: Rendering of Final Design
We'll walk through the design steps, one by one.
There are lots of free CAD programs including Google Sketchup.
The one we used is trueSpace. Don't worry about it being different than the one you use.
They all have the same principles: take simple objects called "primatives" like cubes, rods, toroids (donuts), and spheres; then fuse or subtract them to make more complex structures.
Step 4: Step 1: Open the CAD Program
All of the buttons represent different ways of interacting with the objects that you create.
Every program has different controls. Don't get hung up on the details. Keep the basic idea that
they're all the same, they just look different.
This is the main screen for trueSpace. The tow arrow shaped thing in the center represent light sources in the virtual environment.
This is the stage that we'll build on.
Step 5: Step 2: Open a Draw Panel
The littler window on the left is just another view of the same space but from the top. Most CAD programs let you look at
what you are doing form multiple angles.
Step 6: Step 3: Put Down Some Points That Will Outline Our Shape.
Step 7: Step 4: Give the Outline Thickness
Step 8: Step 5: Subracting a Volume
Next, if we want a hole in the object we need to subtract something from it, see next step.
Step 9: Step 6: Making a Hole
I created a new cylinder object and positioned it over our handle. I looked at the space from the side to make sure that the cylinder was positioned across the outline of the handle. Then I selected the handle as the active object by clicking on it and hit the "Subtract volume" button then selected the cylinder. The cylinder was then subtracted from the handle, leaving a hole behind.
Step 10: Step 7: Render the Scene
Step 11: Step 8: Use the Same Principles to Make the Spoon
Here is the cylinder that we'll use. When you create a new primitive of the cylinder it will let you round the edges, tip the sides, resize the object and lots of other useful things.
Step 12: Step 9: Make the Cylinder Look More Like a Spoon
Step 13: Step 10: Make a Hoolo Space for the Spoon
Use the same technique as before to subtract the ovoid from the stretched cylinder.
Step 14: Step 11: Render the Scene
Step 15: Step 12: Create a Short Handle
Step 16: Step 13: Render the Object
Step 17: Step 14: Render the Scene for Publication.
Choose "sunset" lighting from the lighting panel and a nice surface "texture" or appearance from the material library. Alter the appearence of the surface by changing colors, shininess, reflectivity, bump mapping etc.
Using cyanomethachrolate glue, you can now stick the handle to the spoon at any level to fit your purpose.
The bump on the front rests at the base of the thumb and provides support and the tail rests against the pinky to give lateral stability.
The design process took about 90 seconds. Don't worry about speed, that comes with familiarity with your 3D CAD program. You don't have to spend as much time looking for the right buttons and you have the basic experience to know how to construct the object that you want to make.
First we saved the scene in trueSpace so that we could go back and make changes to these objects any time in the future.
Next we saved our individual objects out of the 3D CAD program (trueSpace) as STL or Stereo lithography files.
Next we opened the individual files in the UP!3D Printer software and hit "Print".
That's about it. 20 minutes later there was a solid plastic object sitting on the platform of the 3D printer.
From design to holding the prototype was 22 minutes and we had time to ask for suggestions about how to alter the objects in the CAD program for the next print.
At about 0.2 cents per gram (35$ for a 1kg spool of 1.75 mm ABS plastic) the prototype weighed 14.4 grams and cost about 3 cents to make.
You can print multiple copies of both parts at a time to make different attachments.
They are now in the software for the Up!3D printer and are ready to go.
The second image is of the Up!3D printer. This is one of several low cost printers available for home hobby use.
They vary in price from 500-3,000 $ and are all essentially comparable, with minor feature variations and
extent of DIY-edness.