One of the first things you learn as a
welder is to tack weld the piece first and finish weld last. There are a few
reasons for this but most importantly it helps prevent warping during the final
bead.
Here the end caps are tacked on.
Once the caps are in place all you need
to do is cut off the corners and you have your octagon shape. I prefer to use a
plasma torch but anything that can cut through 16 gauge will work.
Before you weld always remember to prep
the area by grinding or sanding the area clean of burrs or "junk" left behind by
a cutting torch.
I like to finish weld the caps in place
first. This helps hold the shape of the tank while welding across the length of
the body.
Before welding across the length of the
body I mark the tank for drilling.
Fill tube, top mounts and return/vent(left to right).
Drain plug, feed and bottom mount(left to
right).
Holes drilled on top...
...and bottom.
Don't bother finish welding the body until you've cut out a space for the box to
go into and welded it into place. This will save you a little time a filler rod.
