The size of the support is mainly dependant on two dimensions, the height and width
of the vice jaws in which it is to be used. The maximum distance between the jaws
is though also a consideration. Height is not that critical providing it is say at
least 5mm less than the height of the jaws. However, having completed mine I found
I had chosen a height that coincided with the horizontal vee in one of the jaws.
As a result, thin parts would fall into the vee contacting the lower face which then
lifted it slightly. This situation is best avoided. but can easily be overcome by
placing a piece of steel between the jaw and the support when thin parts are being
For the clearance on the width I would suggest 2mm but of course having made the
device to suit one vice it could equally well be used with a smaller width vice.
I have though dimensioned the workpiece support to fit my Soba drilling vice, being
one of the better drilling vices, but as it is such a simple device the readers should
have no problem in amending the dimensions to suit their own requirements.
My Soba vice has a maximum opening of 100mm but with the springs I had salvaged having
a compression range of 65mm it meant that the device would not be able to cover the
full range. However, I eventually included some adjustment in the design that would
give me the extra required. Reference to photograph 1 will show that the side bars
extend beyond the outer jaw enabling it to be moved back when larger width components
are being drilled.
With a moveable jaw having been incorporated it would be possible for it to work
with much shorter springs but this would necessitate frequent adjustment so decided
to stay with the longer spring as this would minimise the number of times that the
assembly had to be reset. Having set the device for the smaller workpieces, that
is up to 60mm, it is likely that this will satisfy at least 95% of my requirements.
This is relatively simple but there is one very important consideration, that is,
that the holes in the two jaws must align perfectly, if not then the mechanism will
not move freely. To achieve this, clamp the two support pieces together and drill
through both 6mm then opening up one support to 9mm.