Weld Bumps on Exhaust Manifold Shells

 The shells will be spot welded together.  To help make a consistent weld and to provide a guide for where to place the welds I've added weld bumps to the flanges on the lower shells.  The bumps only go on one of the shells.  The point contact of the bump with the other shell assures good contact between the 2 parts at the weld and gives a very small area where the current flows to quickly start the melting for the weld.

You see here a row of weld bumps on the flange of one of the shells.

 Making the bumps is easy.  I use the 1/8" punch in the Whitney punch with the 3/32" die.  This prevents punching a hole.  I also set the die so there is a slight gap between the punch and die when the punch is fully depressed.

This is also the only use I ever found for the depth stop which comes with the punch.  When punching holes I prefer to center punch all holes to control the spacing.  In this case the spacing isn't critical, nor is the exact depth from the edge of the flange.  I've set the stop 1/4" from the center nib on the punch.

 I started with the bumps at each end located by aligning the side of the punch body with the end of the piece.  I also start from each end and work toward the middle.

The original welds on the old manifold were about 1/2" to 5/8" apart.  It works out that the side plates on the Whitney punch make good sights for controlling the spacing.  Just locate the last hole so it's somewhere from the center to the outer edge of the plate and make the next bump.  Trying to handle the spot welder to do that would be much less consistent without some sight gauge added to it.

I'm not after perfect spacing.  This many welds will be way stronger than needed.  By working from both ends to the middle gets the ends the most consistent.  When I get to the middle I just center the last bump, as you can see on the outer edge of this outlet elbow.

It only took a few minutes to add the weld bumps to all the parts for 6 manifolds.