Specifications for Lead Screw Assemblies

Lead Screw Assembly Components

All lead screws are shipped fully assembled and "run in" to intimately mate the screw and nut.

1. Precision Lead Screw

Manufactured of hardened, low temperature stabilized A6 tool steel, in four accuracy grades. Threads are ground and lapped. Thread to thread error as low as 0.000010" including drunkenness. Each screw is "run in" with its own nut.

2. Preloaded Nut

One piece phosphor bronze split nut is self-adjusting. Radially preloaded nut halves respond to the average lead, further reducing residual one turn screw errors. Improved design achieves increased axial stiffness and suppresses backlash.

3. Self-aligning Thrust Bushing

Multiflexured, one piece bushing transfers thrust from the nut to the external load in a theoretically ideal way. Reduces effects of residual eccentricity of lead screw and errors due to slide nonlinearity. Minimizes loading of air bearing slides.

4. Thrust Bearing

Precision preloaded double row ball thrust bearing, in a selection of axial thrust accuracies as good as 0.000010". Thrust bearing error adds directly to the lead screw drunkenness error. Lead screw performance is compromised unless a bearing with equally small errors is selected and properly fitted. We select the best available, epoxy them in place, and retest after fitting. We can also advise you on practical techniques to achieve extreme thrust accuracies better than 0.000005".

5. Optional Lubricator

The optional lubricator, factory installed on the nut, removes dust and lubricates the screw in applications where the screw is exposed and continuous lubrication cannot be provided. Periodic reoiling of the lubricator is required; we can supply the recommended oil.

Precision Lead Screw Assembly - Cutaway


Lead screw material – A6 hardened and low temperature stabilized.

Lead Screw Diameter1/4"1/2"
Maximum Available Travel8"20"
Standard Leads*.025", .050", .100", .200",
1 mm, 2 mm
.025", .040", .050", .100",
.125", .200", .400",
1 mm, 1.25 mm,
2 mm, 2.5 mm, 5 mm
Maximum No-Load Torque4 oz in8 oz in
Maximum Load (Including Inertial)30 lb50 lb
Working Load (Including Inertial)8 lb10 lb
Stiffness of Nut4 lb / .0001"5 lb / .0001"

Lead Accuracy Specification

.000050"/ turn.000025"/ turn.000010"/ turn.000010"/ turn
.000100"/ inch.000050"/ inch.000025"/ inch.000025"/ inch
.0004"/ foot.0002"/ foot.0002"/ foot.0001"/ foot

Bearing Thrust Plane Accuracy

Available.000015", .000010"

We will be glad to review your application and help you specify the lowest cost unit that will meet your requirements. We can advise you on special techniques to increase axial stiffness, and to achieve thrust plane accuracies better than 0.000005".

Standard Universal Lead Screw Assembly Dimensional Drawings


  1. Nut can be factory assembled facing either direction, with clamp area closest to thrust bearing or away from thrust bearing. NUT ASSEMBLY MUST NOT BE REMOVED. Specify desired orientation when ordering.
  2. Optional lubricator is installed on end of nut opposite clamp area. Must be factory installed when lubricator end of nut faces thrust bearing. Adds .38" to length of 1/2" nut, which may reduce travel and/or restrict installation options in some cases. Not available for 1/4" assemblies.

Contact us to discuss your application or request a quote. We will help you specify the lowest-cost solution that will meet your requirements.