Whenever I end up fiddling about trying to set an item vertically in one of the machine vices, and as usual am frustrated by attempting to do it with an ordinary engineers' square, which usually doesn't work, I think of the very simple and elegant solution that Geo. H. Thomas mentioned in a Model Engineer article ( Setting-up Aids ) of nearly fifty years ago! And which, for some reason, I have not got around to putting into practice until now ...
This small gadget is that solution, as described by GHT : the way in which it is used demonstrated by the photo.
I used gauge plate to make the two bits, 1/8" for the stock, 3/32" for the short blade. No picture, but drilled and reamed the two bits together, for the 3/32" iron rivets, while clamped on some plywood with toolmakers' clamps and a 3" square clamped up also to hold the alignment.
I had brought the lower edge of the "stock" to a nice straight edge , checked on a blued parallel ( and the "blade" to parallelism ). But maybe the "stock" had moved slightly, curved a little, after the cutting from a larger piece of plate. So I clamped the stock on the mill, set the blade along the Y axis of the mill truly with a DTI, and just skimmed a few thou along the lower, business edge of the "stock" . That seemed to give nice accuracy to the little tool.
If, as I do, you want to use the square with several ( 4" ) machine vices of rather similar size, make the blade to just miss the base of the one that is shallowest. For smaller vices, like the Myford one, a parallel sat on top of the fixed jaw will enable use on that too. Dave
