Hi guys, when I did my training in the toolroom in the early sixties, we were supposed to do 6 months but I managed to weasel my way to 10 months as there was a lot to do as they say. This kickstarted my lifelong love affair with shaping machines, there being about 5 plus an equal number of horizontal & vertical mills. So I had as a mentor Mr. Frank Dudley, or Dank Frudley as he was known. He showed me the true way of machining flat surfaces & then I set was loose on a 10" butler shaper of truly Victorian vintage, not to worry it was extremely accurate & had a true shaper vice, also box table was capable in conjunction with swivelling vice of creating compound angles in 3 axes at once, Whoa! Being well equipt with parallels, I was then introduced to hold downs, or kicking strips as the old hands called them, there were quite a few about, some stamped with the names of men who retired before I was born. Now a pattern formed, 1 shaper, keen young lad, unlimited supply of gauge plate equals 15 sets of hardened & ground hold downs stamped with owners name, including my 2 sets.
Onward, the included angle when viewed from the end is about 92 degrees & the 2 long edges are ground parallel to each other at this angle, therefore when vice closes on them & the workpiece they tip up in such a way that although the large proportion of the clamping force is gripping across, a small percentage is forcing it downwards. Place a narrow parallel against each jaw, place hold downs on top of them, place 1 large parallel in between to raise job to your required height, tighten vice firmly, caress job once with a LEAD hammer, engage warp drive. I have never known a job to escape from them, still have mine over 50 years later.
About 1980 I finally managed to snaffle a Acorntools 7" shaper made legend in Ian Bradleys book "The Shaping Machine" robjon 44