A box of 9 pairs of wavy parallels.
Select a pair of parallels of the correct height, place in the vice. These are not placed correctly – best to arrange them as a mirrored pair as they can then be squeezed up in the vice and the edges support the workpiece at the maximum width – this is something that an offcut of metal or a blank HSS tool can never do.
Note: check that there is no swarf on the bottom surface of the vice.
Then place the workpiece on top of the parallels.
You do have to be careful if the workpiece is narrow as it can rock leaving it horizontal in the x-axis along the length of the wavy parallel, but not necessarily horizontal in the y-axis.
Therefore, if you can use a pair and it is worth arranging them such that they form a spring in the vice jaws. This will help ensure that the edges of the workpiece are supported before tightening the vice. The vice used here is the mainstay one I use on my milling machine and is a Soba 3″ Swivel Base Vice.
Workpiece nicely clamped up and protruding above the vice and parallel to the bed.
Price: approx £22 for this set in 2010.
You can use pieces of steel etc to jack up the workpiece in a vice, but there are times when you cannot find something that is the correct height or is just too thick. Whether the parallels are metric or imperial does not appear to be an issue as I have really only ever used them based on the fact they are paired and parallel.
Available at rdgtools.co.uk