When using the Horizontal Milling Conversion, the column should be shortened by 2 inches to allow the headstock to be lowered below the top of the table. The drawings in the linked instructions show the operations necessary for you to accomplish this yourself. Longer attachment screws (included with P/N 6100) are required to reach through the 2" block and into the threaded portion of the upper block. The column and saddle may also be returned to the factory where these modifications will be done for you.
Pricing for the modification is as shown below.
New mill at time of purchase--$15.00 added to price of mill
Newer mill column and saddle (2 perpendicular keyway slots in saddle) returned to factory--$30.00
Older mill column and saddle (single keyway slot in saddle) returned to factory--$50.00 (Includes milling 2nd keyway slot.)
6101 Sherline Column Conversion Instructions