Wednesday, June 27, 2007

gin pole

This is the plan for the gin pole we'll use for the next raising. The "A" frame will pivot on a couple of simple brackets made from 2 x 6's and a long 3/4" bolt pinned to the playa with re-bar staples.

Monday, June 25, 2007


Saturday afternoon, 4 of my camp mates joined me for the first raising of the full tower. We succeeded in standing the tower up but not without breaking a stave and then breaking a few more on the trip down. I learned a lot about the forces being applied during erection and have a few modifications to make before the next attempt.

The first point of failure was a stave on the horizontal triangle connecting the first and second section. When the tower is in its upright position these triangles are in tension - but when the tower is being raised they were subjected to compression forces that proved to be too much for these thin members. In addition, the contact points of the vertical sections apply an eccentric loading to the triangles that ultimately caused the stalks to crush and fail when loaded in compression. I have an idea about how to correct the problem that I will implement in the next build.

Another aspect of the raising that needs some improvement is the gin pole. We opted for a single pole this time instead of the intended "A" frame, not surprisingly it turned out to be a little unstable. I'll make sure the "A" frame model is ready for the next raising.

A big thank you to David, Mark, Brad, Matt and my wife Jenny for helping move this process forward.

Wednesday, June 20, 2007

tower in the yard

I've finally figured out that I have just enough room in my yard to erect the tower. So last night after dinner I began assembling the pieces - and much to my surprised delight - I was able to put the entire thing together in about an hour. I guess I learned a thing or two from last year's project! I have a bit more work to do on guy wires and the gin pole before we'll be able to raise the tower - I'm shooting for Saturday.

Thursday, June 14, 2007

pistil light test

Pistil - like in a flower. In addition to the L.E.D. lights - I've been working on this cylindrical array of cold cathodes that will reside in the center of the top section of the tower. The array consists of 16 - 12 inch long cold cathode tubes controlled by a 10 channel sequencer I built. Currently it's set to cycle through 10 different patterns.

Monday, June 4, 2007

weekend progress

It was a productive weekend. With the help of my camp mate Magpie, I was able to get the bottom half of the tower into a standing position - it's very stable and solid. I've completed all the sections now and have begun experimenting with some configurations for the top. I'm really liking the curvy look. I'd like to erect the entire tower next weekend in the big field and let it stand in the elements for a while. It's looking like the tower will be around 75' tall with the top in the current configuration!