UniSlide® A25 Series – Dual Screw Drive Models
Two independently controlled lead screws, allowing the two carriages to move independently along the same linear axis.
SKU:
A25XXPXX-S2.5-1-1-1The A25 Series UniSlide® Dual Screw Models (-DS) offer two independently controlled lead screws, each with its own knob, allowing the two carriages (sliders) to move independently along the same linear axis. This configuration is a variation of the Left-Right Screw Motion model, providing full independent control for applications requiring flexible, precise, or complex positioning.
Each A25 Series UniSlide® Assembly is precision-built from a rigid aluminum alloy extrusion featuring 60° opposing V-type dovetail ways for alignment accuracy and stability. The aluminum alloy carriage rides smoothly in the dovetail ways, guided by machined surfaces that ensure repeatable, low-resistance motion.
Features
Two carriages, each driven by a dedicated lead screw and control knob
Rigid aluminum alloy dovetail base with 60° opposing V-type ways
Smooth, repeatable motion with precise manual control
Compact, low-profile design suitable for multi-axis setups
Load capacity up to 30 lbs. (horizontal)
Available in travel distances up to 24.5 inches
Specifications
Factors such as size of the motor, size of the payload, travel distance, mounting direction/plane, etc. effect the actual capability of any assembly. Please contact Velmex Application Engineers to configure a system that will meet your exact requirements.
| Operating temperature | 0 to 180° F (-18 to 82° C) |
Properties of Velmex Stages - Information on stage composition, tolerances, wear and design for specialty applications.
Load Parameters - Definitions and parameters that effect the various load ratings.
| Standard | Metric | |
| Travel Distance | 1.5" - 24.5" | 3.81 – 62.23 cm |
| Base Length | 3.0" - 27.0" | 7.62 – 68.58 cm |
| Slider Length | 2.5" | 6.35 cm |
| Weight | 1.0 – 3.68 lbs. | 0.45 – 1.67 kg. |
| Height** | 0.81" | 2.06 cm |
| Width | 2.5" | 6.35 cm |
‡ Standard travel distances available are in 3″ increments.
Available in a variety of English and Metric lead screw pitches.
UniSlide® A25 Load Calculations
| Load Capacity | lbs. | kg. |
| Maximum Horizontal Load | 30 lbs. | 13.6 kg. |
| Horizontal Central Load | 30 lbs. | 13.6 kg. |
| Cantilevered Load †† | 40 lb-in | 4.52 N-m |
| Vertical Central ** | 10 lbs. | 4.5 kg. |
| Load Normal (LN)* | 10 lbs. | 4.5 kg. |
| Load Thrust (LT)* | 3 lbs. | 1.36 kg. |
| Cantilever Side (LCS)* | 10 lb-in | 1.13 N-m |
| Cantilever Inline (LCI)* | 20 lb-in | 2.26 N-m |
* Normal Operating Loads are less than the maximum.
** For A25 models with 1/4″ or 7 mm diameter lead screws: 10 lb or 4.5 kg
** For A25 models with 3/8″ or 10 mm diameter lead screws: 30 lb or 15.5 kg
†† Maximum momentary load.
Lead Screw Specifications
| Repeatability | 0.00015″ (4 microns) typical |
| Straight line accuracy | 0.003″ (0.076 mm) over entire travel distance. Higher accuracy 0.0015″ (0.038mm) available |
| Screw lead accuracy | 0.003″/10″ (0.076 mm/25 cm) 0.0015″/10″ available. Consult factory. |
English Thread Lead Screws
| Pitch | Backlash Typical | UniSlide™ Code | |||||||
| Turns per inch | Advance per revolution | English | Metric | Degrees | Standard Accuracy | With Scale and Vernier - Standard Accuracy | With Graduated Knob - Precision Accuracy | Division on Graduated Knob | Lead Screw Diameter |
| 40 | 0.025" | 0.00013" | 0.003 mm | 1/200 rev or 1.8° | C | CE | P40 | 25 | 1/4" |
| 20 | 0.05" | 0.00025" | 0.006 mm | 1/200 rev or 1.8° | B | BE | P20 | 50 | 1/4" |
| 10 | 0.1" | 0.0005" | 0.013 mm | 1/200 rev or 1.8° | W1 | W1E | P10 | 100 | 3/8" |
| 5 | 0.2" | 0.001" | 0.025 mm | 1/200 rev or 1.8° | W2 | W2E | P5 | 200 | 3/8" |
| 2.5 | 0.4" | 0.002" | 0.051 mm | 1/200 rev or 1.8° | W4 | - | - | - | 3/8" |
Metric Thread Lead Screws
| Pitch | Backlash Typical | UniSlide® Code | |||||||
| Turns per cm | Advance per revolution | English | Metric | Degrees | Standard Accuracy | With Scale and Vernier - Standard Accuracy | With Graduated Knob - Precision Accuracy | Division on Graduated Knob | Lead Screw Diameter |
| 10 | 1 mm | 0.0002" | 0.005 mm | 1/200 rev or 1.8° | K1 | K1M | Q1 | 100 | 7 mm |
| 5 | 2 mm | 0.00039" | 0.01 mm | 1/200 rev or 1.8° | K2 | K2M | Q2 | 200 | 7 mm |
*Adjustable nut models (A25,A40,A60) can have backlash adjusted to near 0. Manual applications only
Options/Accessories for A25 UniSlide® Assemblies
A2500XY Adapter Plate
To mount an A25 or MA25 Series UniSlide to another A25 or MA25 Series or to an A15 or MA15 Series in XY.
A2500XZ Adapter Plate
Mount an A25 or MA25 Series UniSlide® to another A25 or MA25 Series or to an A15 or MA15 in XZ.
A2501XZ Adapter Bracket
To mount an A25 or MA25 Series UniSlide to another A25 or MA25 Series (6″- 9″) or to an A15 or MA15 Series (6″- 9″) in XZ. (The A25 or MA25 would be the base horizontal stage. The other stage would be mounted vertically.)
A4000XY Adapter Plate
To mount an A40 or MA40 Series UniSlide to another A40 or MA40 Series or to an A25 or MA25 Series in XY. (The A40 or MA40 would be the base stage.)
A4000XZ Adapter Plate
Mount an A40 or MA40 Series UniSlide or an A25 or MA25 Series vertically to another A40 or MA40 Series in XZ.
A4001XZ Adapter Bracket
Mount an A40 or MA40 Series UniSlide (6″- 9″) or an A25 or MA25 Series (6″- 9″) vertically to another A40 or MA40 Series in XZ. Can also mount two B4800TS Rotary Tables at right angles.
B2503XZ Adapter Bracket
To mount an A25 or MA25 Series UniSlide to another A25 or MA25 Series (over 9″) or to an A15 or MA15 Series (over 9″) in XZ.
B4003XZ Adapter Bracket
Mount a vertical A25, MA25, A40, or MA40 Series UniSlide® Assembly (12″–15″ travel) to a horizontal A40 or MA40 Series UniSlide® base stage in an XZ configuration.
B4004XZ Adapter Bracket
To mount an A40 or MA40 Series UniSlide to another A40 or MA40 Series (over 15″) or to an A25 or MA25 Series (over 15″) in XZ. (The A40 or MA40 would be the base horizontal stage.)
B5990TXZ-BK Adapter Plate
Use this bracket to mount two B5990TS Rotary Tables at right angles to each other or to mount a B5990TS to a UniSlide® Linear Stage.
UniSlide® Slider Lock
This lock is mounted at the mid-point on the base and is tightened to prevent slider movement.
UniSlide® Thumbscrew-on-Lead-Screw Lock
An easy method to affix the slider utilizing a simple thumbscrew on the lead screw at the end bearing block of each axis.
UniSlide® Traveling Slider Lock (-TSL)
This lock attaches to the slider to lock the carriage in place.
A25 / A40 Series Right Angle Gearbox
Ideal for tight spaces or applications where access to the end of the stage is limited.
A25 Alternative Knobs
A variety of knob styles can be substituted for the standard knob on any UniSlide® Assembly.
B29 Platform Shelf
Platform shelf from UniSlide® A25 and MA25 Elevating Tables that can be used on vertical UniSlide® Assemblies.
Left-Right Screw Motion
This configuration enables two carriages to travel along a shared axis using a single lead screw while moving towards or away from each other.
Optional Finishes
Many Velmex Products come standard with a brushed aluminum finish. Optional finishes including Black Anodizing are available.
Retainer Nut Wrench
Custom-designed wrench specifically made to adjust and remove the threaded retainer nut found on select UniSlide® Assemblies.
Slider Lengths
All UniSlide® Assemblies are available with a variety of carriage (slider) lengths to suit different application needs.
Two Independent Carriages
Separate and precise positioning along the same linear axis using two lead screws.
UniSlide® Way Covers
Way Covers protect the slider and dovetail base from dust, dirt and grit that could hamper the efficient operation of the slide, thereby extending the life of the slide.
UniSlide® Revolution Counter
The mechanical counter provides a convenient lead screw revolution count. This aids in determining position and providing a reference number for the location of the carriage / slider.
UniSlide® Vacuum Modifications
Stages for use in vacuum environments can be customized with special materials, coatings, and seals to ensure compatibility with low-pressure conditions and minimize outgassing
Velmex offers a multitude of options and accessories for all its products. Usually an option or an accessory will address your requirements. When it doesn’t, we can make custom modifications, including:
• Additional holes or slots. (A drawing is required.)
• Intermediate plates to mount your payload
• Special or in between lengths of the dovetail base
• Lead screw shaft extensions
• Choice of drive nut materials, including brass and Vespel
We can also offer customized configurations to address special environmental and vacuum applications.
Applications and Examples
Note: the example displayed may be a custom configuration, designed to the customer’s specifications; and not offered as a standard product. Custom configurations could contain custom, externally-fabricated components.

Downloads
The majority of CAD drawings found in our Technical Library are Step (.stp) files. You will also see .dxf, .dwg, .sat and .pdf files. For .STP files, you may need to right click on the download button and save the “target” or “link”. If you require a different format or cannot located the drawing you require, please contact us.
| Title | Summary | File Type | Link | hf:file_type |
|---|---|---|---|---|
| A2504A-S2.5.stp | Free Slide, 1.5″ Travel | stp | stp | |
| A2504D-S2.5.stp | Rapid Advance – limited adj., 1.5″ Travel | stp | stp | |
| A2504Dx-S2.5_scale_vernier.stp | Rapid Advance – limited adj. with scale and vernier, 1.5″ Travel | stp | stp | |
| A2504Gx-S2.5_micrometer.stp | Rapid Advance – limited adj. with micrometer, 1.5″ Travel | stp | stp | |
| A2504Hx-S2.5_scale_vernier.stp | Rapid Advance – unlimited adj. with scale and vernier, 1.5″ Travel | stp | stp | |
| A2504Hxx-S2.5.stp | Rapid Advance – unlimited adj., 1.5″ Travel | stp | stp | |
| A2504xx-S2.5_scale_vernier.stp | Lead screw. with scale and vernier, 1.5″ Travel | stp | stp | |
| A2504xx-S2.5.stp | Lead screw, basic knob and crank, 1.5″ Travel | stp | stp | |
| A2504xxx-S2.5-TL Small Knob.stp | Lead screw, basic knob and crank, small knob, with thumb lock, 1.5″ Travel | stp | stp | |
| A2504xxx-S2.5.stp | Lead screw, graduated knob, 1.5″ Travel | stp | stp | |
| A2506A-S2.5.stp | Free Slide, 3.5″ Travel | stp | stp | |
| A2506D-S2.5.stp | Rapid Advance – limited adj., 3.5″ Travel | stp | stp | |
| A2506Dx-S2.5_scale_vernier-SLL.stp | Rapid Advance – limited adj. with scale and vernier, 3.5″ Travel with left mounted slider lock | stp | stp | |
| A2506Dx-S2.5_scale_vernier.stp | Rapid Advance – limited adj. with scale and vernier, 3.5″ Travel | stp | stp | |
| A2506Gx-S2.5_micrometer.stp | Rapid Advance – limited adj. with micrometer, 3.5″ Travel | stp | stp | |
| A2506Hx-S2.5_scale_vernier.stp | Rapid Advance – unlimited adj. with scale and vernier, 3.5″ Travel | stp | stp | |
| A2506Hxx-S2.5.stp | Rapid Advance – unlimited adj., 3.5″ Travel | stp | stp | |
| A2506x-S2.5-LR.stp | Lead screw,basic knob, left / right dual carriages, 1″ Carriage separation | stp | stp | |
| A2506xx-S2.5_scale_vernier.stp | Lead screw. with scale and vernier, 3.5″ Travel | stp | stp | |
| A2506xx-S2.5.stp | Lead screw, basic knob and crank, 3.5″ Travel | stp | stp | |
| A2506xxx-S2.5-RC.stp | Lead screw,graduated knob and crank, 3.5″ Travel, with rev counter | stp | stp | |
| A2506xxx-S2.5-TL.stp | Lead screw, graduated knob and crank, 3.5″ Travel, with thumb lock | stp | stp | |
| A2506xxx-S2.5.stp | Lead screw, graduated knob, 3.5″ Travel | stp | stp | |
| A2509A-S2.5.stp | Free Slide, 6.5″ Travel | stp | stp | |
| A2509D-S2.5.stp | Rapid Advance – limited adj., 6.5″ Travel | stp | stp | |
| A2509Dx-S2.5_scale_vernier.stp | Rapid Advance – limited adj. with scale and vernier, 6.5″ Travel | stp | stp | |
| A2509Gx-S2.5_micrometer.stp | Rapid Advance – limited adj. with micrometer, 6.5″ Travel | stp | stp | |
| A2509Hx-S2.5_scale_vernier.stp | Rapid Advance – unlimited adj. with scale and vernier, 6.5″ Travel | stp | stp | |
| A2509Hxx-S2.5.stp | Rapid Advance – unlimited adj., 6.5″ Travel | stp | stp | |
| A2509x-S2.5-LR.stp | Lead screw, basic knob, left / right dual carriages, 4″ carriage separation | stp | stp | |
| A2509xx-S2.5_scale_vernier.stp | Lead Screw with scale and vernier, 6.5″ Travel | stp | stp | |
| A2509xx-S2.5.stp | Lead screw, basic knob and crank, 6.5″ Travel | stp | stp | |
| A2509xxx-S2.5.stp | Lead screw, graduate knob, 6.5″ Travel | stp | stp | |
| A2512A-S2.5.stp | Free Slide, 9.5″ Travel | stp | stp | |
| A2512D-S2.5.stp | Rapid Advance – limited adj., 9.5″ Travel | stp | stp | |
| A2512Dx-S2.5_scale_vernier.stp | Rapid Advance – limited adj. with scale and vernier, 9.5″ Travel | stp | stp | |
| A2512Gx-S2.5_micrometer.stp | Rapid Advance – limited adj. with micrometer, 9.5″ Travel | stp | stp | |
| A2512Hx-S2.5_scale_vernier.stp | Rapid Advance – unlimited adj. with scale and vernier, 9.5″ Travel | stp | stp | |
| A2512Hxx-S2.5.stp | Rapid Advance – unlimited adj., 9.5″ Travel | stp | stp | |
| A2512x-S2.5-LR.stp | Lead screw, basic knob, left / right dual carriages, 7″ carriage separation | stp | stp | |
| A2512xx-S2.5_scale_vernier.stp | Lead Screw. with scale and vernier, 9.5″ Travel | stp | stp | |
| A2512xx-S2.5.stp | Lead screw, basic knob and crank, 9.5″ Travel | stp | stp | |
| A2512xxx-S2.5.stp | Lead screw, graduate knob, 9.5″ Travel | stp | stp | |
| A2515A-S2.5.stp | Free Slide, 12.5″ Travel | stp | stp | |
| A2515D-S2.5.stp | Rapid Advance – limited adj., 12.5″ Travel | stp | stp | |
| A2515Dx-S2.5_scale_vernier.stp | Rapid Advance – limited adj. with scale and vernier, 12.5″ Travel | stp | stp | |
| A2515Gx-S2.5_micrometer.stp | Rapid Advance – limited adj. with micrometer, 12.5″ Travel | stp | stp | |
| A2515Hx-S2.5_scale_vernier.stp | Rapid Advance – unlimited adj. with scale and vernier, 12.5″ Travel | stp | stp | |
| A2515Hxx-S2.5.stp | Rapid Advance – unlimited adj., 12.5″ Travel | stp | stp | |
| A2515x-S2.5-LR.stp | Lead screw, basic knob, left / right dual carriages, 10″ carriage separation | stp | stp | |
| A2515xx-S2.5_scale_vernier.stp | Lead Screw with scale and vernier, 12.5″ Travel | stp | stp | |
| A2515xx-S2.5.stp | Lead screw, basic knob and crank, 12.5″ Travel | stp | stp | |
| A2515xxx-S2.5.stp | Lead screw, graduate knob, 12.5″ Travel | stp | stp | |
| A25182Hx-S2.5_scale_vernier.stp | Rapid Advance – unlimited adj. with scale and vernier, 15.5″ Travel | stp | stp | |
| A2518A-S2.5.stp | Free Slide, 15.5″ Travel | stp | stp | |
| A2518D-S2.5.stp | Rapid Advance – limited adj., 15.5″ Travel | stp | stp | |
| A2518Dx-S2.5_scale_vernier.stp | Rapid Advance – limited adj. with scale and vernier, 15.5″ Travel | stp | stp | |
| A2518Gx-S2.5_micrometer.stp | Rapid Advance – limited adj. with micrometer, 15.5″ Travel | stp | stp | |
| A2518Hxx-S2.5.stp | Rapid Advance – unlimited adj., 15.5″ Travel | stp | stp | |
| A2518x-S2.5-LR.stp | Lead screw, basic knob, left / right dual carriages, 13 ” carriage separation | stp | stp | |
| A2518xx-S2.5.stp | Lead screw, basic knob and crank, 15.5″ Travel | stp | stp | |
| A2518xxx-S2.5.stp | Lead screw, graduate knob, 15.5″ Travel | stp | stp | |
| A2521A-S2.5.stp | Free Slide, 18.5″ Travel | stp | stp | |
| A2521xx-S2.5.stp | Lead screw, basic knob and crank, 18.5″ Travel | stp | stp | |
| A2524A-S2.5.stp | Free Slide, 21.5″ Travel | stp | stp | |
| A2524xx-S2.5.stp | Lead screw, graduate knob, 21.5″ Travel | stp | stp | |
| A2527A-S2.5.stp | Free Slide, 24.5″ Travel | stp | stp | |
| A2527xx-S2.5.stp | Lead screw, basic knob and crank, 24.5″ Travel | stp | stp | |
| A2530A-S2.5.stp | Free Slide, 27.5″ Travel | stp | stp | |
| Manual UniSlide® Dimensional Drawings | Dimensional drawings for the 5 Series of Manually Operated UniSlide® Linear Stages | |||
| UniSlide Manual Spec Overview | Overview of Manual UniSlide® Assemblies | |||
| UniSlide® Users Manual | Operating and Service Manual for UniSlide® Stages |
Knowledge Base
| Motion | Linear |
|---|---|
| Maximum Travel | 80" (203.2 cm) |
| Minimum Travel | 5" (12.7 cm) |























