Introduction: Tetra Table
- Inner Triangles: Mahogany
- Inner Triangle Edges: Purple Heart
- Outer Middle Parallelograms: Mahogany
- 3x Hexagon Edge: Walnut
- Outer Octagon: Red Oak
- 3/4" Birch Ply
- 1" Steel Bar Custom Brackets
Designed in Rhinoceros 3D
The concept for this tabletop came from a floor design for a geodesic dome. I wanted to geometrically transition from 3 (the triangle in the middle), to 8 (the octagon on the outside). I started by cutting shapes from scrap materials, and the project transformed into the following table design with a complimentary base. I consider the base a prototype, as I'd love to redo it in a nicer wood someday. If I were to build a similar design again, I would definitely consider attaching the table-top pieces with biscuits for added strength.
Step 1: Table Top Design
No fancy code or algorithms used. The geometry is all designed by hand, using Rhino's snapping tools.
The Rhino (.3dm) file is attached if you want to explore the design, or make one yourself.
Step 2: Mahogany Interior Triangles
Cut w/Table Saw Jig.
Unfortunately I am lacking documentation in these first steps, as I was "in the zone". I essentially marked the angles on the stock, and used a custom table saw jig make my cuts.
Step 3: Purple Heart Triangle Edge and Mahogany Pieces
Cut w/Table Saw Jig
Step 4: Ratchet Strap for Setting/Gluing.
Step 5: Table Base Design
Created by intersecting two tetrahedrons (3-sided pyramids), and removing the bottom with a boolean plane.
Step 6: Adding Thickness
Using the 'extrude' tool, I thickened the pieces.
Step 7: Tablesaw Jig Design for Mitre Cuts
I measured the angles between the pieces with the Angle tool, and designed some mitre jigs explicitly for the form. I aligned the mitre-edge to the vertical table saw blade, and then engineered the jig to support the workpiece with clamps as it gets cut.
I could have also utilized the mitre-angle of the table saw, but it's more precise and less confusing to leave the blade at a vertical 90 deg.
Step 8: Cut File
Step 9: Laser Cut Forms and Jig Pieces From 3/4" Birch
Using the Metabeam at Pier9, cut from high quality 3/4" ply.
Step 10: Sanding Laser-Burnt Edges Off
Step 11: Jig Assembly
Cross members made from 1/2" ply.
Step 12: Cut Mitres With Table Saw Jigs
I attached each piece to the jig after I labeled each edge so I would stay organized. I pushed each jig through the saw by hand after attaching the workpiece to the jig with clamps.
Step 13: Finished Mitre Cuts
Step 14: Measure Interior Angle With Laser-Cut Angle Template
Angle calculated from CAD file, laser cut on an Epilog laser cutter at Pier9. There is only one angle to measure, which makes it easy.
Step 15: Cutting, Breaking/Bending
Using the laser-cut angle template, I used the metal break to match the angle I needed.
Since the form is a tetrahedron, all the interior angles are identical.
Step 16: Drill Holes, Countersink Brackets
In the metal shop at Pier9
Step 17: Pre-drill Holes, and Attach Brackets W/Wood Screws
A little piece of tape on the drill bit keeps from plunging too far.
Step 18: Bracketed Panel Assembly
I loved this part. It was satisfying knowing that I got the mitre cuts right.
Step 19: Base Assembly Finished
Step 20: Sanding Down Tabletop
Lots of dust.
Step 21: Mitre Tabletop Edges
One last finishing move.
Step 22: Assembly
Not Pictured: I added small walnut feet on the underside of the tabletop to keep it from shifting around.
Step 23: Finishing W/Beeswax
Non-toxic, orange oil and beeswax.
Step 24: Complete
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