Instructables
Intro:
   
Welcome to the Spiral Coffee table Instructable. I hope you will enjoy reading this Instructable as much as I did in creating it.  I will also be providing all of the files and formulas used in the construction. Any customization of the table is welcome. Now, lets start off with the purpose and goals in making this project.

Purpose:
     The purpose of this design is to make a visually appealing and structurally sound coffee table.

Goals:
    
Several main goals existed in this project:
       1)  To illustrate the steps of starting conceptually from a conceptual idea appealing furniture.
       2)  To utilize CAD for precise dimensions and assembly fluidity.
       3)  Create tooling that was easy to use for repeatable results.
       4)  Compare a Virtual-created model to Physical result.

Safety:
Power tools ,woodworking and stain/paints are used for this project, so please, use safety-glasses and gloves when appropriate.

Now comes the brainstorming the concept of the table.
 
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Step 1: Conceptual Design and Equations

Picture of Conceptual Design and Equations
Eqn Drawing 1.JPG
Equation Capture.JPG
Concept:
    I started off on this project deciding on what would be a handsome table and was interesting from the top down-design. I choose the spiral design of the legs. I then had to support the structure, so I had designed each leg be supported by the previous, as well as an optional base for additional support.

Trigonometry:
    
Coming up with an initial design wasn't too hard. However making an appeasing twist and correct height involves some trigonometry. The major factor of this table was the side length. An easily measured length was one driving fator(round numbers are nice!)
     1)  The projected length (c)  and side length (l) were used to find a suitable height for a coffee table (around 19" high)
     2)  Since the average coffee table is around 20" in height, choosing the correct lengths and angles were important in make an attractive table
     3) A Law of Cosines and a Pythagorean theorem later, and I had a useful formula to implement in the CAD software.
    
Next up, CAD:
triumphman2 years ago
Can you safely put any weight on this table?
Rbeny (author)  triumphman2 years ago
Yes, each leg gets its strengthened from the rest of the group. It would be significantly weaker if one or more of the legs was missing. Earlier, I tested the strengths of the glued joints, The pine failed at ~90 ft-lbs of torque (45 lbf @ 2 ft from the joint). If you were to use a Hardwood ,the failure stress should be at least 5 times that of pine.

I also stacked 75 lb on the stand, and it held fine. As for any more weight than that, it would probably depend on your choice of wood. I didn't design the table to be a stool anyways.

Hopefully this answer is satisfactory on how much weight you can put on the table.
Nice instructable! I'd LOVE to try this soon!
Rbeny (author)  YellowBlu Co.2 years ago
Great! I would LOVE to hear how it goes.
Jackwer2 years ago
Cool