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Velmex Tree Ring Measuring System (TA)

  Velmex Tree Ring Measuring System  


The Velmex "TA" system is specifically designed for the researcher to perform non-contact measurement analysis. Since it's introduction, the Velmex "TA" system has been the standard of North America's Dendrological Research Community. The "TA" system is successfully being used for many diverse application such as:


• Tree ring growth measurements

• Growth study of mollusks

• Ecological effects on coral 

• Probe positioning

• Precision bore camera inspection

• Material stress analysis

• Other applications requiring high accuracy non-contact measuring/positioning.

The System delivers accuracy with increased durability and compactness at an affordable price.

System Components*

The "TA" system consists of the following three main components:

UniSlide TA System

Velmex TA System with a UniSlide Linear Stage, the VRO Readout, optional Tab2 Remote Reset. (Encoders on stage, but not visible.)

1. UniSlide® dovetail rapid advance screw motion assembly, available in several travel lengths. Lead screw hais a metric 10 x 1 mm pitch.

2. One micron (0.001mm) resolution linear encoder integrated to the UniSlide assembly.

3. Velmex VRO™ Encoder Readout for connection to the linear encoder and interface serially to a computer for measurement recording/logging. (VRO-1B with base)


1. VXM-USB to RS232 Serial Cable

2. VRO-TAB2 remote reset and send remote input module

*Components sold separately

The Velmex system does not include a microscope or the specific analysis software. Velmex only provides the positioning system.

Tree ring research software is available at projectj2x at www.voortech.com.

  • Other Links
  • Specifications
  • Accessories
  • Downloads / Documents / Instructions
  • Examples (Images / Articles)


Velmex is a manufacturer of positioning devices used to measure and count tree-rings from a cookie or core. We are not engaged in the actual science or analysis process. If you are interested in that aspect, here are some excellent resources:

University of Arizona - The Laboratory of Tree-Ring Research

Cornell University - Cornell Tree-Ring Laboratory

International Tree-Ring Data Bank

James Cook University, Australia - Tropical Dendrochronology Laboratory

Lamont-Doherty Earth Observatory - Tree Ring Lab

- Lamont-Doherty Tree-Ring Software (this is not a complete list) - Software

University of Nevada - Dendro Lab

Bolin Centre for Climate Research - Stockholm University

The Tree Ring Society

Ultimate Tree-Ring Web Pages (This site is not currently live. Because of the excellent information on the science of tree-rings, we are now linked to an archive view.) Web Site: Ultimate Tree-Ring Pages

These are just a few of the many universities and organizations that use the Velmex TA Measuring System for tree-ring research. They focus on different research areas including the study of the climate and climate change, other environmental research, dating wooden objects and structures, and other archaeological research.


UniSlide® TA Measuring System Overall Specs
Travel Distance Inches 3" - 24"
Centimeters 7.62 – 60.96
Base Length Inches 9" - 30"
Centimeters 22.86 – 76.2
Slider Length Inches 6"
Centimeters 15.24
Maximum Horizontal Load lbs. 100
kg. 45.5
Weight of UniSlide lbs. 6 - 13
kg. 2.7 - 5.9
Weight with Encoder lbs. 6.08 – 13.1
kg. 2.74 – 5.95
Width - carriage Inches 4"
Centimeters 10.16
Width - with mounting plate Inches 5.25"
Centimeters 13.3
Height Inches 1.06"
Centimeters 2.69
Lead Screw 10 x 1 mm pitch 10 turns per centimeter
1 mm advance per revolution

UniSlide® TA Measuring System - Individual Model Number Specifications
UniSlide Model Number Travel Base Length Weight AMO Encoder,
1um Resolution
Inches cm Inches cm lbs. kg. lbs. kg.
TA4009H1-S6 3" 7.62 9" 22.86 6 2.7 ENCINDL1-03 0.08 0.04
TA4012H1-S6 6" 15.24 12" 30.48 7 3.18 ENCINDL1-06 0.08 0.04
TA4015H1-S6 9" 22.86 15" 38.1 8 3.63 ENCINDL1-09 0.08 0.04
TA4018H1-S6 12" 30.48 18" 45.72 9 4.08 ENCINDL1-12 0.08 0.04
TA4021H1-S6 15" 38.1 21" 53.34 10 4.54 ENCINDL1-15 0.08 0.04
TA4024H1-S6 18" 45.72 24" 60.96 11 5 ENCINDL1-18 0.08 0.04
TA4027H1-S6 21" 53.34 27" 68.58 12 5.44 ENCINDL1-21 0.08 0.04
TA4030H1-S6 24" 60.96 30" 76.2 13 5.9 ENCINDL1-24 0.1 0.045


UniSlide® TA Measuring System Dimensional Drawing

TA System Dimensional Drawing

Accessories for Use With the Velmex Tree Ring System

Accessories are available to configure a Tree Ring Measuring System to meet your specific requirements. All accessories are priced separately.

VRO with an UniSlide Assembly

Encoders and VRO™ Encoder Readout For a high resolution position readout an encoder and Velmex's VRO encoder readout can be mounted to any UniSlide TA Assembly. An encoder, mounted directly to the slider gives a true and accurate reading eliminating lead screw and backlash errors.

The VRO Readout monitors the linear incremental encoders integrated into the UniSlide® stage. Fully functional, it features automatic memory back-up of settings, sleep mode and self diagnostics. It's highly visible, wide-screen LED display makes it easy to view the positioning results. SEE: Velmex Controls on the Encoders and the VRO Readout for additional details.

REQUIRED for system operation.

Power Supply

VRO™ Power Supply - The universal power supply is standard with all VRO Readouts. It can also be ordered separately.

REQUIRED for system operation.

Power Supply

Linear Encoder - A one micron (0.001mm) resolution linear encoder is integrated to the UniSlide TA Assembly. The Encoder length matches the slide's linear travel distance.

REQUIRED for system operation.

VRO Tab2 Remote

VRO-Tab 2 Hand-held, two button remote which provides a convenient capture (upload VRO reading to computer) and reset of the VRO for faster data collection.

RECOMMENDED for system operation.

Power Strip

Power Strip – Convenient power strip for plugging in multiple VROs and VXMs™.

- Optional

International Power Adapters

International Power Adapters – a variety of international-rated power adapters are available.

- Optional

VRO Cables

Assorted Cable Adapters - Various adapters are available to connect to computer via USB and to various brands of linear and rotary encoders.


USB to RS232 - allows the VRO Readout to communicate with the computer. (10 ft.)

- REQUIRED for system operation.

Encoder Cables - connects the encoders to the VRO to transfer position data. (Specified based on travel length.)

VRO End Caps

End Caps Rubber end caps protect the corners of the VRO Readout and the component connections from accidental damage.

- Optional

VRO Moisture Protection

Vinyl Bag A clear vinyl bag protects the VRO from fogging in high moisture situations and/or transporting outdoors.

- Optional

COSMOS for VRO C.O.S.M.O.S.™ (Computer Optimized Stepper Motor Operating System) can be used in conjunction with a Velmex VRO™ Readout. It coordinates communication between the computer and the VRO readout. While its primary function is to aid set-up and programming of the VXM™ Controller to control Velmex motorized positioning systems, COSMOS can send commands to emulate the buttons on the front panel VRO Readout.

See Software for more information on COSMOS, along with computer notes, drivers and VXM programming examples.


Any microscopes, cameras, measuring software and other tools utilized are not provided by Velmex.

Tree ring research software is available at projectj2x at www.voortech.com.

TA Measuring System CAD Drawings
Series Type File Name Description Download View
Tree-Ring STP TA4030H1-S6 AMO Encoder.stp UniSlide Rapid Advance A40 24" Travel, 6" carriage, with encoder mounted Download Button -
Tree-Ring DWG TA4030-S6 with AMO Encoder 2D mounting drawing.dwg UniSlide Rapid Advance A40 24" Travel, 6" carriage, with encoder mounted Download Button -
Tree-Ring PDF TA4030-S6 with AMO Encoder 2D mounting drawing.pdf UniSlide Rapid Advance A40 24" Travel, 6" carriage, with encoder mounted - View PDF


TA Measuring System Documents

Type File Name Description Download View
PDF TA System 7-1-14 Rev C.pdf Specification Sheet for the Velmex TA System Download Button View PDF


TA Measuring System Instructions

Type File Name Description Download View
PDF TA System Layout- fade.pdf Layout showing how the components of the system are configured. Download Button View PDF
PDF TA System Care and Use 8-15 Rev A.pdf Instructions - Care of the TA System Download Button View PDF


Tree Ring Lab UniSlide and VRO on a tree cookie UniSlide and VRO on a tree cookie
TA Measuring system with UniSlide and VRO set-up in a laboratory. TA Measuring system with UniSlide on a tree cookie. (Encoder has been replaced with AMO.) TA Measuring system with UniSlide, VRO and a Tab 2 set-up.
Paul Sheppard dating violin Dendrochronoligst Gordon Jacoby Log Cabin Dating
Paul Sheppard from the University of Tennessee at Knoxville works on dating the Messiah Violin using a TA system. The late Dendrochronologist Gordon Jacoby measuring tree rings with Velmex TA system. A TA Measuring System in use dating the wood from a log cabin.
UniSlide TA system with BiSlide Side Knob    
A UnISlide® TA system with the microscope mounted on a BiSlide® Side-Knob Assembly.    


Here are some interesting articles that mention the use of the Velmex TA Measuring System in dating projects:

• April, 2015 - Sewanee Today - Tree Ring Date of Rebels Rest

• August, 2014 - The New Yorker - World Trade Center Ship

National Park Service - Great Smoky Mountains - History of Fire

• April, 2006 - Vision Systems Design - Positioning systems help tree ring research

There are thousands of research articles, papers and abstracts on the internet that cite the use of the Velmex TA Measuring System in tree ring related projects and studies.