Hi Bob,

That's strange that a negative value in the text thickness doesn't work for you, it works over here.
You can also move the letters at a distance by using Transform>Move then when you pick the base point hit the TAB key,
this will highlight the numerical read out area at the bottom of the window and there you can type a desired value, then when
you move your object it will move in any direction at that value.

Once your happy with the depth of the letters in the shank use Construct>Boolean>Diff (difference) to make an 'impression' of those letters.

I've attached your model back with it set up ready for the Boolean operation and a copy after the command has been executed.
You'll notice that I also rotated the lettering to be parallel to the shank surface angle, I used the edit frame to do this, you can find out
more about the edit frame in the help files at the following link http://moi3d.com/2.0/docs/moi_command_reference11.htm#editframe

P.S. The Letter 'H' wasn't a solid so I had to fix that up for Boolean to work properly.

Cheers