Easiest, cheapest, most precise, most customizable, with user selectable alignments (Lofgren A or B, Baerwald, Stevenson), radii, user input of pivot to spindle distance (any arm ever made!), is the Conrad Hoffman Arc Protractor. Just line your tip to the entire arc swing, then make parallel to ONLY ONE null point, and you’re done. No trial and error, no guessing. Takes about 5 minutes per alignment. I’ve had no troubles using Micro Ridge, or any other tip profile. Always accurate. And…. It’s free. It’s customized to YOUR arm, your table.