Introduction: CAD Design for Coffee Filter

I was building the CNC during 3D printing day so I am uploading a tutorial on CAD design in Rhino. The learning curve is relatively steep but once you have done it a few times the controls will be completely intuitive.

Step 1: Drafting

I was taught to start in 2D and work up to 3D. As such, I drew a top down view of my filter and brought the contours into 3D using the loft and extrude commands.

Rhino works on the command line. Typing "circle" is the same as pressing the circle button. If you have never used the command line before, endeavor to learn. You will grow to love it.

Type circle. Press enter. Click where you want the center of your circle to be. Look at the menu on the left and check the "Diameter" box. Type 3. A 3" diameter circle will appear. This is the outer border of our filter.

Create a 2.75" and 2.875" circle. These will be the fitting that keeps the filter in the mug.

Create 3 0.5" holes. These are what the coffee will drip through as it migrates into the cup. Clicking the red arrow will allow you to type values that will move the holes on the x-axis.

Step 2: More Drafting

Draw a line through the middle of your circle and move it up .5"

Draw a line through the middle of your circle and move it down .5"

Use the Trim tool to trim the lines to the middle large circle (Trim > Select Cutting object (Circle)> Enter > Select objects to cut (Ends of lines) >Enter)

Make a copy of the outside circle and move it up 3 inches on the Z.

Step 3:

Offset your top circle and your circle/line contour inward by .125.

Loft outside to outside and inside to inside.

Select both top contours and Patch them.

Trim the center out using the inner circle as the cutting object.

Step 4:

Extrude your outside circle down .125. Extrude your two interior circles down .25.

Step 5: Extra Credit

- Experiment with adding fillets or a handle!

- Export as .STL files if you intend to 3D print.