Overview - Steady Rest Provision

Applies to machines built from: 
February, 2012
This document tells you about the Steady Rest Provision. This option supplies the necessary mounting platform and hydraulic lines to install a Steady Rest on lathes. This option is for ST-40/40L/45/45L/50/55 lathes.
  1. Mounting Platform.
  2. Mounting Bracket.
  3. Gripper.
    note: The Haas Steady Rest Provision does not include the mounting bracket [2] or the gripper [3]. The manufacturer of the steady rest supplies these.



  • The mounting platform [1] uses the tailstock linear guides.
  • The mounting bracket [2] is attached to the mounting platform [1].
  • The gripper [3] is attached to the mounting bracket [2].


  • The steady rest supports long workpieces [4] during turning and boring operations.
  • You can install a manual or hydraulic steady rest to the platform [1].
  • You manually set the position of the platform [1] along the Z Axis.


A tailstock is necessary to use the steady rest provision.


The steady rest manufacturer installs the bracket and grippers on the mounting platform. The steady rest manufacturer has bracket and gripper installation instructions.

Hydraulic Hoses

The hydraulic fittings [1] are below the bottom door rail.

The fittings at the end of the hoses are male JIC-4.

The steady rest manufacturer supplies the hydraulic hoses for the gripper.


Use the instructions in the manufacturer’s steady rest operator’s manual to align the steady rest.


  • When you use the tailstock, monitor the position of the steady rest platform. If you do not monitor the position, a collision could occur.
  • Adjust the hydraulic pressure at the Hydraulic Pressure Unit (HPU). The hydraulic pressure controls the steady rest gripping force.
  • Make sure that the steady rest pressure is not higher than the pressure that the manufacturer recommends.
  • The workpiece must have a smooth, concentric diameter to let the grippers hold the workpiece correctly.
  • Do not put rough material in the steady rest grippers.
  • Examine the screws that hold the steady rest to the platform. Make sure they are torqued correctly.
  • Keep your hands, loose clothing, tools, and equivalent items away from the steady rest when it closes.


Steady Rest Rollers

You can put 2 types of rollers in the steady rest gripper.

  1. Straight Rollers. Use straight rollers for standard cylindrical parts.
  2. Crowned Rollers. Use crowned rollers for tapered parts.



Maintenance schedules and procedures are different for each manufacturer.

Maintenance cycles can be daily, weekly, monthly or hourly. Refer to the lubrication and maintenance schedules in the manufacturer’s manual for information.

Do this each day:

  • Examine the steady rest rollers for wear.
  • Make sure that no play is in the roller bearings.
If you find play, replace the roller.


Too much play in the roller bearing causes these problems:

  • The part does not turn true in the grippers.
  • Unsatisfactory accuracy.
  • The chuck throws parts.
The rollers are a normal wear item. The manufacturer’s manual tells you how to replace the rollers and how to get them.



Use M-codes to automatically open and close the gripper.


  1. M59 P1155 closes (clamps) the gripper.
  2. M69 P1155 opens (unclamps) the gripper.
If you command M59 and the gripper opens, the hydraulic lines are installed incorrectly. Change the positions of the hydraulic hoses at the hydraulic fittings for the steady rest.


Do a rough turning operation on the work piece where the grippers hold the part. This makes sure that the rollers touch the part consistently. Then close the grippers to engage the part.

This is an example of a program on a lathe with a steady rest provision. This program assumes the part is supported with a tailstock.




G00 G53 X0

G00 G53 Z0

T101 (Rough Turn)

G50 S600 (Limit RPM)

G97 S325 M03

G00 Z0.25 M08

G00 X12.5

G96 S500

G01 X11.5 F0.05

Z-20.00 F0.02


G00 X12.5 Z0.25

G00 G53 X0



M59 P1155 (Gripper Close Activate)

G97 S100 M3

M22 (Retract Tailstock)

G00 G53 B0 (Send Tailstock Home)

T202 (2” Diameter Drill)


G00 Z0.5 M08

G00 X0.0

G01 Z-5.0 F0.006

G00 Z0.25 M09

G00 G53 X0

M69 P1155 (Gripper Open Activate)


T303 (Finish Turn)

G50 S600 (Limit RPM)

G97 S450 M03

G00 Z0.25 M08

G00 X12.0

G96 S600

G01 X11.45 F0.05

Z-20.00 F0.012


G00 X12.5 Z0.25

G00 G53 X0 M09





Capacity Notes


Lathe Model Maximum Part Weight** Maximum Weight of a Gripper and Bracket
ST-40/40L/45/45L ST-50/55 2000 lb (907 kg) 500 lb (227 kg)


Refer to Lathe - Weight Limits for the Workpiece for more information.

Steady Rest Base Plate Screw Pattern and Work Envelopes

Steady Rest Travel Limits

For steady rest travel limits refer to haascnc.com

Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.

Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.