back to How to Build and Run the GEK Gasifier
The GEK building scenario let's you decide the relative amount of "effort vs cost" you want to invest towards your finished unit. As GEK vessel dimensions are based on common scrap tanks found in North America, you can choose to build it for minimum money (and maximum effort) with the dimensions, instructions and CAD files provided here. The local junkyard will provide all the greasy tanks you need. Of course you can also just buy the sheet metal parts precut and ready to go from ALL Power Labs, but some of us do insist on doing this the hard way. For an example of a scrap tank built GEK, see the v0.7 photos here.
The "build it from junk" scenario requires scrap tanks of 10", 12" and 14.75" nominal diameter. 10" is typical for hand held air transfer tanks and some truck pony tanks. 12" is typical for 5 and 10 gal propane tanks (you may have to splice two together to get adequate length). 14.75" is typical for a 100lb/25gal propane tank. Be warned: There's a surprising amount dimensional variation on "standardized tanks" between different tank manufacturers. This can complicate the fit of flanges and end plates to the scrap tanks.
Manually cutting accurate flange rings and end plates is the hardest task. Using a compass to guide your torch/plasma is required. You can make a simple guide compass using a metal bar with rotation point on one end and cup to hold torch on the other end. One of the two ends needs to slide so you can adjust the radius.
Here's some links showing the basic idea. Forget about the fancy wheels to roll the rotated end. Dragging the bar and cup works just fine. But make sure your cutter is ok to drag on the surface, or design your cup so the torch is supported at an appropriate height above the surface.
http://videos.streetfire.net/video/Cutting-Perfect-Circles-w_178210.htm
http://www.shopfloortalk.com/forums/showthread.php?p=182159
http://www.youtube.com/watch?v=L4C6sCTTtI4