All my machine tools are buried right now. Building a shop extension and everything is piled up and I can't get to it to confirm anything. However, the stock 5400 has 8" clearance. The 15" column should add 4" to that and the column riser adds another 2" so theoretically, yes, 14". Subtract the tooling plate and milling vise and I would guess you end up somewhere near 12" max to the bed of the vise. The vast majority of the time you will be working down close to the vise but the extra space gives you room to use tooling that otherwise wouldn't fit.