Cross Slide Mill Post Watchmakers, Jewelers, Machinist With Dovetail Keyway Bottom. It measures approximately 1 3/16 across bottom edge. Please examine photos carefully for a more accurate description. We will move quickly to answer. Just add the items to your cart and select the. We have been purveyors of New England antiques for 46+ years and have recently retired. We will do everything in our power to represent our pieces honestly and for a fair price.