Wednesday, April 23, 2008

Sourcing parts

One of the major challenges in this project has been finding sources for some of the materials I've needed. To date, I've done 4,887 Google searches and accumulated 237 bookmarks. In addition to the cycling specialty shops and solar energy suppliers you might expect, I've gleaned insight and ordered materials from an assortment of highly specialized industries and niche hobbies I never knew existed. Here's a list of some of my favorites:

  • Aerospace - satellite-grade solar cells (Emcore via eBay)
  • Fire performance - as in breathing and juggling fire. Bought Kevlar tape to make an abrasion-resistant border around the solar module (Bearclaw Manufacturing)
  • Sculpture - fiberglass mesh for first solar module (Compleat Sculptor)
  • Auto racing - aluminum rivets
  • Boat building - marine-grade wiring and electrical components
  • Remote controlled hobby airplanes - power meter/fuel gauge (RC Electronics)
  • Veneer woodworking - vacuum bagging supplies (Veneer Supplies)
  • Star Wars replica costume builders - plans for vacuum forming machine (TK560)
Imagine all of these people at a cocktail party trying to make small talk.

Tuesday, April 15, 2008

Expert Help Wanted

I'm currently working on a problem with composite core construction. Are you an expert in this area? Can you point me in the right direction? WARNING: I'm about to seriously geek out on you here. If you don't understand what I'm talking about, this entry is not for you.

How can I maximize the strength to weight ratio in a fiberglass/Baltek Mat layup?

Here's the layup: Tap Marine Grade Epoxy with slow hardener (143), 2 mm Baltek Mat with 3.7 oz "S" glass on either side using a hand layup. Pressing it between two boards while it cures gives excellent strength but at 0.40 lb/sq ft it seems needlessly heavy and resin rich. Same layup under vacuum bagging, Mylar on one side, polyester peel ply and breather/bleeder on the other at 5" Hg drops the weight down to 0.23lb/sq ft but the stiffness suffers and there's noticeable compression (30-40%) of the core material. I'm using this as the structural support for the next solar module and I'm looking for maximum stiffness and minimum weight. Carbon fiber is a little too spendy at $40-60/yd. As a composites novice, am I really going to see performance gains if I go with carbon?

Sunday, April 13, 2008


Here's an older slideshow with more information about the genesis of this project. I put this together in October of 2007 so it's a little out of date. If you want to read the captions you can pause the auto-play feature and advance through the slides manually.