18″ NexGen Benchtop Mill w/Ball Screws – CNC-Ready


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2 to 4-week lead time

  • *Preferred unit of measurement for laser engraved portions
    Please note that our ball screws only come in a metric pitch
  • *Will you be using Sherline’s CNC driver box?
  • Package Options
    (click magnify icon to view package contents)
  • Available CNC Components
    Optional CNC controllers & stepper motors for the mill. Click on images to view product page
         Mill CNC kit with high-torque motors            High-Torque Stepper Motor

Product Description

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.

L: 5800 w/standard leadscrew
R: 18″ ball leadscrew mount
Click on the image for a larger view.

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

Click on the image for a larger view.

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).

Ball Leadscrew Specifications

  • Rolled Ball Screw with BSH Nut
  • 10mm Diameter, 2mm Lead
  • C7 Accuracy*, P1 Preload
    *C7 accuracy has a linear tolerance of 50 micrometers / 300mm or .002″ / 12.0″.

The ball screws are only available in metric, so the numeric graduations on the handwheel dials are 2mm per revolution and .02mm per line.

Standard equipment for the model 6858 CNC-ready mill includes:

  • A powerful 90V DC motor with electronic speed controller
  • 18″ base
  • Electroless nickel/Teflon coated mill saddle
  • 18.0″ (457 mm) x 2.75″ (70 mm) table with two T-slots
  • 7″ x 13″ tooling plate with three T-slots
  • 15″ mill column bed with nickel/Teflon coating
  • Stepper-motor mounts with high-torque couplings
  • The handwheels are included and can be mounted to the end of the stepper motors to maintain manual control when needed.* 2-1/2″ (63mm) adjustable “zero” handwheel on the Z-axis and 2″ (51mm) adjustable “zero” handwheels on the X- and Y-axes. Each handwheel has laser-engraved aluminum handwheel collars
    *NOTE: CNC-ready machines cannot be operated manually unless double-shaft stepper motors are installed.
  • ¼” Drill Chuck w/ key, #1 Morse arbor with drawbolt
  • Pulleys, drive belt, three hexagonal keys, spindle bars, gib removal tool, eight-foot three-wire power cord, and instruction manual
  • Oil reservoirs on the X/Y axes and the Z-axis to help keep critical parts lubricated.
  • Brass leadscrew cover that keeps chips off the rear of the Y-axis leadscrew
  • Accordion way cover

The improper use of machine tools and their accessories can result in serious injury. Before using this tool, thoroughly read the instructions and make sure you understand its proper and safe use.


Always wear safety glasses when operating machine tools.

Download PDF Assembly and Instruction Guide

Instructions PDF Download

Download PDF 6858 Exploded View

Instructions PDF Download

Download PDF Ball Screw Mill Unpacking and Assembly Notice

Instructions PDF Download

Download PDF Instructions for Sherline Limit Switches and Mounts

Instructions PDF Download

Download PDF 5920/5958 Ball Screw Way Cover Instructions

Instructions PDF Download

Download Lubrication for Ball Screw Machines PDF

Instructions PDF Download

Download Ball Screw Lubrication PDF

Instructions PDF Download

Max clearance
(table to spindle)
12.875″ (327 mm)
(no spacer)
(w/ headstock spacer)
Travel, X-Axis 12.80″ (325.1mm)
Travel, Y-Axis 11.00″ (279 mm); 8.9″ (226 mm) with tooling plate attached
Travel, Z-Axis 9.25″ (235 mm)
Hole through spindle .405″ (10 mm)
Spindle nose thread 3/4″-16 T.P.I.
Spindle nose taper #1 Morse
Spindle runout of Morse taper .0005″ or less
Handwheel graduations .02 mm
Electronically controlled spindle speed range 70 to 2800 RPM
Width Overall 20.375″ (518 mm)
Depth Overall Base footprint: 21.125″ (537 mm); With fully extended brass leadscrew cover: 28.375″ (721 mm)
Height Overall (Max.) 26.5″ (673 mm)
Table size 2.75″ x 18.00″ (70 x 457 mm)
Hold-down provision 3 T-Slots (with 7″ x 13″ tooling plate)
Shipping Weight 82 lb. (37.27 kg)
Movements in addition
to X-, Y- and Z-axes
Headstock rotation (90° left/right), Column pivot (90° Fwd/Bk), Column travel (In/Out) 5.5″ (140 mm)
Motor 90 volt DC with electronic speed control that accepts any incoming current from 100VAC to 240 VAC, 50 Hz or 60 Hz.
Click here for motor specifications
Spindle Speed Range 70-2800 RPM continuously variable by electronic speed control