About the 18″ Base CNC-Ready Mill with Ball Screws
This machine is based on our 18″ NexGen 5800-series mill. The 18″ mill base with ball screws comes with all new saddles developed for the ball screws, and #23 NEMA frame stepper-motor mounts with high-torque couplings.
The X/Y-mill saddle has been beefed up to accommodate the larger ball screws, and it has an electroless nickel/Teflon coating. This coating offers a hard surface that is rustproof, while the Teflon provides a friction coefficient of .1-.2u for smoother movement of the saddle and the table.
The new ball screw design for the column saddle reduces the overall Z-axis travel by 1.4″. Because the ball-nut does not allow the column saddle to move down as far as the old style column saddle, we made the new ball screw column saddle longer. This will allow you to move the headstock closer to the top of the mill table. However, you will still lose 1.4″ of overall travel in the Z-axis.
The Z-axis column bed on the 18″ ball screw mill is mounted directly to the swing arm with an arm mount, unlike the 5800 NexGen mill that utilizes a movable clamping disk. This effectively eliminates the side-to-side rotational axis of the column bed.
The Axes of Movement of a Sherline 6858 Ball Screw Mill
The table left/right movement is referred to as the X-axis. The table in/out movement is the Y-axis. Headstock up/down movement is referred to as the Z axis. The headstock can also be rotated on its saddle on Sherline mills (#4), the column ram can be moved in and out (#5), and the Z-axis column can be tilted forward and back (#6).