Geodesic Dome Assembly

Intro | Strut Creation | Assembly Notes | Strut Assembly | Design Choices
Dome Home | Covering


The dome struts are made of metal 3/4 inch electrical conduit. We turn raw conduit into struts by cutting them to length, flattening the ends, and drilling holes at the flattened ends. Assembly order is important - start from the top, not from the bottom.

Strut Creation

Note: if you're going to do this yourself, consider buying or borrowing real tools instead of the ones we describe below. After helping with another dome-style building project, it's *much* nicer to have a drill press plus jig, an arbor press to flatten, and last but not least a Makita worm drive circular saw with a metal cut-off abrasive disk to cut the pipes. You can see pictures of all of these in action on Howard's Nose-building Party page. I'm making lots of sparks with the Makita about halfway down. See also Howard's Home Dome page for detailed power tools advice.

Bill of Materials

Cutting the Struts

We cut two sizes of struts: the long ones were 76.3 inches, and the short ones were 67.6 inches. (See the Desert Dome Calculator page for how to get these numbers given that we want a 2-frequency 20-foot diameter dome.)

A pipe cutter looks like this:

You just twist the knob until the blade eats all the way through the conduit. There's enough mechanical advantage that it's not too much work to do one pipe.

Assembly Notes

Assembly Sequence

  1. Start with the struts, cable-tied in bundles of 5 for easy transport: 30 short ones and 35 long ones.

  2. Lay down five shorts in a star shape. (Three of these struts are specially marked since they have holes drilled into them where the plastic hat mini-struts will be bolted on later.)

  3. Bolt the struts together at the central vertex. They'll end up elevated a few inches off the ground at the center.

  4. Lay down five long struts, one along each side of the pentagon formed by the short ones.

  5. Loosely bolt the vertices, so that one diagonally vertical short is between two horizontal longs. The center point will now be further up off the ground. There's absolutely no point in tightening these vertices past the bare minimum to hold the nut on the bolt, you'll be disassembling them soon.

  6. At each of the five vertices, lay down a short, then two longs.

  7. For each vertex, unbolt it and add the three new struts (long, short, long). You will probably have to struggle to get all six struts on, since the flattened parts of the struts inevitably don't quite fit together right at this stage. Do as much as you can to encourage them (lots of shaking and shoving). For pernicious ones, you can give up on gentleness: just screw the bolts through the strut holes. Although this will strip the bolt, it will by God make everything fit.

  8. You'll "walk" the dome up higher. The three struts that you just added are the legs that you'll use to walk it up. Yank up on a vertex, so that the struts are less criss-crossed. You might have to make sure the ends dig into the ground so that it doesn't slip. As you circle the dome doing this for every vertex, it will gradually stand taller and taller. After three or four full circuits, it will be at the height you want, where the short struts are vaguely close to vertical.

  9. At each short strut, lay a horizontal pair of short struts, one on each side.

  10. There are two kinds of vertices to bolt at this stage. One kind has three struts: a short vertical between two short horizontals. The other kind has four struts: two slanted vertical longs and two horizontal shorts.

  11. At the three-strut vertices, lay down a short strut on both sides, then lay down a long strut on both sides, for a total of four struts.

  12. At the three-strut vertices, bolt the shorts to the vertex. Let the new struts end up on the outside of the structure. At the four-strut vertices, bolt the longs to the vertex. Let the new longs stay on the inside of the structure. (The short ends in the picture are attached to the neighboring 3-strut vertices.)

  13. You'll now "walk" the dome up again, using the new struts as the legs. This time will be more work, since the structure is heavier. You'll probably want to yank up on the vertex with one hand while positioning the struts at a sharper angle with respect to the ground with the other hand. You may also get better results by skipping to every other vertex so that yanking up doesn't undo the work you just on the nearest neighbor . Although it may seem like you're taking one step back for every two steps forward, after several circuits you'll reach the point where the struts meet in pairs to form triangles.

  14. Lay a long strut between every pair of almost-vertical struts: that is, at the base of the triangles.

  15. Bolt the vertex so that each triangle has a long at the base.

  16. Go around to all the eye-level vertices and shake the structure from each one, to level everything out.

  17. Tighten the vertices, starting from the top and working your way down. Since the very top is now 10 feet tall, you'll probably want a ladder for this part. The best tools to use are a fixed wrench for the outer bolt top, and a deep-well ratchet wrench for the inner nut.

  18. Wrap the top five vertices to keep the sharp struts from abrading the tarps. This year, instead of towel scraps after the fact, we're trying preventative wrapping before putting on the tarp with chamois tape (the kind you wind on the handles of tennis rackets). A roll is $2.50 for three strips, and two strips per vertex seems good...

Design Choices

Tamara Munzner
Last modified: Mon Jul 29 17:12:17 PDT 2002