Skip to main content
                     
As-Built As‑Built - Revit As‑Built - AutoCAD VirtuSurv - VirtuSurv 2018 As‑Built - Modeler            
BuildIT BuildIT - Metrology BuildIT - Projector BuildIT - Construction              
CAM2 CAM2 - SmartInspect CAM2 - AnthroCAM CAM2 - 2018 CAM2 - Measure 10 CAM2 - Measure Q CAM2 - Measure X CAM2 - Measure 3/4      
Cobalt 3D Imager 3D Imager - Cobalt                  
Computers Computers - All Computers                  
FARO Aras 360 & CAD Zone FARO 360 - Reality FARO 360 - HD FARO 360 - Blitz FARO 360 - Genius FARO CAD Zone - Fire & Insurance FARO CAD Zone - Crime & Crash FARO CAD Zone - CZ Point Cloud FARO CAD Zone - First Look Pro    
FARO Zone FARO Zone - 2D FARO Zone - 3D                
FaroArm/ScanArm FaroArm/ScanArm - Edge ScanArm - Design ScanArm ScanArm - Forensic ScanArm ScanArm - Design ScanArm 2.5C ScanArm - Design ScanArm 2.0 FaroArm/ScanArm - Quantum S FaroArm/ScanArm - Quantum M FaroArm/ScanArm - Quantum E FaroArm/ScanArm - Fusion FaroArm/ScanArm - Prime
FaroArm/ScanArm FaroArm/ScanArm - Platinum FaroArm/ScanArm - Legacy Quantum FaroArm/ScanArm - Titanium FaroArm/ScanArm - Advantage FaroArm/ScanArm - Digital Template          
Gage Gage - Bluetooth Gage - Plus Gage - Standard Gage - Power            
Hand Held Scanner 3D Hand Held Scanner - Freestyle3D 3D Hand Held Scanner - Freestyle3D X 3D Hand Held Scanner - Freestyle3D Objects 2D Hand Held Scanner - ScanPlan            
Language Quality HT MT AT NT INT - Internal          
Languages Language - English Language - Japanese Language - German Language - Chinese Language - Spanish Language - Italian Language - French Language - Portuguese    
Laser Projector RayTracer - RayTracer Laser Projector - Tracer M Laser Projector - Tracer SI              
Laser Radar Imaging Laser Radar - VectorRI                  
Laser Scanner 3D Laser Scanner - Focus S 3D Laser Scanner - Focus M 3D Laser Scanner - Focus3D 3D Laser Scanner - Focus3D X 3D Laser Scanner - Focus3D X HDR 3D Laser Scanner - Focus3D S 3D Laser Scanner - Photon      
Laser Tracker Laser Tracker - Si Laser Tracker - ION Laser Tracker - Vantage S6 Laser Tracker - Vantage Laser Tracker - X Laser Tracker - Xi Laser Tracker - Vantage S Laser Tracker - Vantage E Laser Tracker - Vantage E6  
Legacy Software Legacy Software - CAM2 Gage Legacy Software - Gage Software Legacy Software - Insight              
Photonics Scan Head - Digi-Cube Scan Head - Xtreme Scan Head - 3D-Contour Scan Head - 3D-Ultralight Scan Head - 3D-XB Controller - Maestro 3000 Controller - LEC Series      
PointSense PointSense - Basic PointSense - Pro PointSense - Building PointSense - Plant PointSense - Heritage PointSense - Revit CAD Plugin - TachyCAD Building CAD Plugin - TachyCAD Archeology CAD Plugin - TachyCAD Interior CAD Plugin - PhoToPlan Basic
PointSense CAD Plugin - PhoToPlan CAD Plugin - PhoToPlan Pro CAD Plugin - DisToPlan CAD Plugin - MonuMap CAD Plugin - hylasFM CAD Plugin - VirtuSurv CAD Plugin - PhoToPlan Ultimate      
RevEng RevEng - RevEng                  
SCENE SCENE - Capture and Process SCENE - WebShare Server and 2Go SCENE - WebShare Cloud SCENE - WebShare 2Go App SCENE - 2018 SCENE - 4.x SCENE - 5.x SCENE - 6.x SCENE - 7.x SCENE - LT
Serial FaroArm Serial FaroArm - Bronze Serial FaroArm - Gold Serial FaroArm - Silver              
Visual Inspect Visual Inspect - App Visual Inspect - CAD Translator                

Laser Tracker

ION

Si

Vantage

Vantage E

Vantage E6

Vantage S

Vantage S6

X

Xi

English

FARO® Knowledge Base

Accuracy Issues with the Hidden Point Bar or Bar Extension Accessory

Some applications contain measurements of locations that are difficult to place the SMR on directly requiring use of the Bar Extension commonly called the Hidden Point Bar. When a Bar Extension is combined with the 1.5” Shankless Nest and Point Tip or Sphere Adaptor, a sphere can be measured and the desired point is the center point of the sphere. The measurements should be taken very carefully to avoid any movement or slippage of the bar’s tip while ensuring adequate coverage of the sphere. There diameter of the measured sphere can be determined by combining the lengths of the bar, tip, nest and SMR and this information can be used to evaluate the measurement to validate it. Some common scenarios for an inaccurate measurement is listed below. Five or more readings on the sphere measurement are required to obtain this information.

Inaccurate Sphere Diameter, High Standard Deviation of Sphere Fit, Poor Form of the Sphere (or any combination of these three):
Indicates that the measurement of the sphere is not accurate or repeatable. The point bar tip may have moved during the measurement. If the sphere fit adaptor is being used, the Tooling Ball being measured may be moving in hole it is inserted. Another possibility is the 1.5” Shankless Nest is not securely attached to the top of the bar and is moving during the measurements.

Inaccurate / Inconsistent Sphere Diameter combined with a low Standard Deviation of Sphere Fit and good Form of Sphere:
Indicates that not enough the sphere is being measured. Sphere fit algorithms require a certain amount of a spheres surface be measured to calculate its diameter and center point accurately. If not enough of this surface is measured, then the sphere fit can return a low standard deviation and form but with an incorrect diameter. For example, NIST testing showed Measure Q can produce accurate results with partial spheres that contained 30 degree bands of data. When using the 10” Bar with the Point Tip, moving the SMR only around 1 to 2 inches produces only 5 to 10 degree band and can produce this effect. Moving the SMR around 4 to 5 inches would be required to obtain the 30 degree band and would produce the correct sphere diameter and center point.


Keywords:

Hidden Point Bar Problems, Sphere Fit Problems, Bar Extension Problems, Hidden Point Bar Accuracy, Bar Extension Accuracy