Tentman,
The backer is turned to slightly less than the diameter of the inside of the bolt,then inserted; the two bolt halves are then adjusted so the witness marks line up.The two halves, having been ground to form a V, can be held in a V-block, vise, or however is convienent to the welder, for tacking together. Once tacked, it can be removed and finish welded.Care should be taken to keep the heat as even as possible to prevent warping.After tacking,though,the alignment and length should be verified. The locking lugs must be kept cool enough to keep them from being annealed. Wet rags(kept wet frequently)and/or "Heat Stop" can be used for this.While they can be later rehardened(surface), it would be a good idea to keep the camming surfaces cool also. It's been a very long time, when I had to work for a living, backer rod was avaliable from "McMaster Carr". BTW the rod has to be left long enough that it can be withdrawn after welding. As an extra advantage, the backer leaves the inside smooth enough that it shouldn't have to be cleaned up.In my,not very well respected,opinion; the best welding procedure would be MIG, then TIG.Gas welding and stick welding have been used,but controling the heat would be harder.As always, someone else may know of a better way.
Mike
