keeping DTIs perpendicular for runouot checks

[Neale]

How about...
Set up DTI with base and support block, etc, so plunger is horizontal. That's easy enough clear of the spindle. Put DTI on bed and move carefully up to spindle so plunger starts to move. Rotate whole block/DTI "lump" slowly and carefully about the centre of the supporting block so the plunger moves across the shaft you are measuring, and the max plunger movement corresponds to perfect alignment. That might work...

[dsc]

Set up DTI with base and support block, etc, so plunger is horizontal.

That's the issue Neale, how do I know if plunger is horizontal? is it good enough to just set it by eye and assume it's horizontal? or is there some way to have it 100% horizontal, parallel to the surface on which the mag base is?

The other issue is that I have to points off which I can measure, one is a surface which is perpendicular to the shaft, the other surface is an unknown, it's definitely not perpendicular to the shaft as it's slightly off. If I measure off the first surface, all I need is the plunger to be parallel in relation to the surface, then it's perpendicular to the shaft. If I go with the second surface (much easier, more room), I need to set the plunger in relation to the shaft as I have no other point of reference.

Regards,
T.