Paul (and Doug)  A week or so ago the subject of how to keep the oil pan
flange flat during welding came up.  I have tried a lot of different
schemes but what I am doing now works perfectly.  The fixture is a flat
piece 1/4 steel same size as the pan flange (15.25 x 12.75 in the case
of the Renesis).  On the bottom I have tacked some 1.5" angle iron to
lift the steel plate off the table to facilitate clamping.  You will be
amazed at how light the clamping pressure need be.  I started out with
bolting the flange down all around,  then I switched to heavy c-clamps
but now all I use are spring clamps three to each side.  One of the
pictures is of the finished product with the clamps removed.  You can
see that is lying flat,  no problems.  Jerry