The Beginnings of the Frame

After a great many hours of staring at a Sketchup model and reading through Locost 7 design blogs, I've started the actual fabrication of the frame.  Nearly all of the tubing used in the build, both round and square, will be 16 gauge 1" or 1.5"

 In red you can see the part of the front sub frame I plan on keeping:

The plan is to use the original control arms and control arm towers to retain all of the geometry of the Mazda front end.  Notice in the photo below how the upper control arms rotate about an axis which is not parallel to the lower axis.  This is one of many complex angles that have been designed into the system that surpasses what I would be able to recreate in a simple Lotus 7 style front end.

I've first welded a cross member between the two towers which I'll retain so that I can cut away the rest of the sub frame and all of the control arm connection locations will remain.

I then welded what I call a Christmas tree to any of the points that needed to remain in an accurate location after the frame is cut away.

Here I've cut the extra subframe away with a plasma cutter:

After I have these towers I can start turning the Sketchup model into reality.  I'm using a 4'x8' sheet of plywood as a platform for laying out the bottom of the frame.  I've set it on the flattest part of my garage floor and put shims under any low points so that I have a true flat surface to work with.  Then I can draft the locations of tubes and intersections directly on the platform.

I've used some blocks to hold all of the tubing true for the first several tack welds.