Here's a bit more data on how these jigs were made. I've decided to mod the tube holding design and removed the original DeStato clamps, the tube resting pads and "wall". Under them I found bluing still there and one can see the layout marks used to locate the various mounting holes.




Perhaps the more machinist savvy of us can provide some insight. I find it interesting that the bluing is still present and that the hole locating lay out lines are still visible. I believe it was during the 1970s that the movement to X-Y coordinate locating started in any volume. The use of lay out bluing and lines suggests an "old school" manor of fabrication. Just what I would expect of an older and experienced machinist to use if they were not wanting to duplicate the design.

I am starting a new thread covering what I change on these jigs. Andy