Should be able to use the linear pattern (bottom left of the 9 button group) to set two "holes" on a 30deg line, put your dti into the spindle and adjust vice until it reads zero on two "holes" placed a couple of inches apart.

Could also use trig to work out the X&Y for a given length of line at 30deg.

Edited By JasonB on 15/01/2017 16:34:33

Only if you happen to have one

As Michael says a set-square is quick and usually accurate enough, easy if you have a dovetail column mill to hold one side agaist that and the othe against the fixed vice jaw or a flat bar held in the vice

I see there is also an incline function, this can be used in a similar way as the linear pattern, just enter a large value for the step say 2" or 50mm and angle of 30deg.

Another option if you have a rotary table is to mount the vice onto that and clock it in true then rotate table 30deg.

It is easy to check the angle, if not set it. Reading x and y at two points will give you the tangent of the angles by dividing one into the other.

To follow MichaelG's observation that sin 30 is 0.5 the easiest way to apply this is to measure the length of your vice jaws and offset one end half this length off the other along the X axis. For example if you have 4" vice jaws the Y axis value of one end should be 2" different from the other end.

Martin