There is a box section that forms the inner edge of the canvas top.  This box section runs from the top of the windshield up over the roof all the way down to the bumper.  For want of a better term, I am going to call this box section a roof rail.

RoofRail

Here are the portions of the roof rail that are missing:

Missing Bits

Here is what the roof rail looks like after cutting out the box section:

InnerRoofRailBoxRemoved

I experimented with  different methods for forming new roof rails and produced a whole lot of scrap before I hit on a useful answer.  Bending them over a simple MDF form did not work properly because the tubing springs back.  This can be fixed by building the form with a tighter radius curve.  On the internet there are a ton of tables that you can use to figure out how tight to make the curve to compensate for spring-back.  But there is a hitch (Isn’t there always?), the roof rails are a diminishing radius curve – a spiral.  Maybe there are math whizzes out there who can figure out how to compensate, but I sure can’t.

So I tried making V notches in the tube, bending the tube at the notches then re-welding the notches. Well that didn’t work because the weld shrinks ever so slightly as it cools.  It is not much at each notch, but over the length of the roof rails it adds up and the curve comes out wrong.  Also, each V-notch is a potential failure point.

So, I hit on the idea of making a bending tool using a honking great vise, two pieces  of 1/2″ threaded rod and a chunk of 1/8 strapping. Tightening the vise pushes the strapping against the tubing, creating a bend. Here is the bending tool in the vise with a newly completed bend.  Through experiment, I managed to come up with a thickness of strapping that bends the tubing by 5 degrees over 4″.

IM000002

Here is the partly bent rail in the vise.

IM000001

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