Line and end standard

Line and end standard

1. Line Standard and End Standard
Instructor
Mr. GauravBharadwaj
AssistantProf.
DepartmentofME
GLAUniversity

2. Introduction
•Alengthmaybemeasuredasthedistancebetweentwopoints,twolinesorasthedistance
betweentwoparallelfaces.
•So,theinstrumentsfordirectmeasurementoflineardimensionsfallintotwocategories.
1.Linestandard
2.Endstandard

3. Line Standard
•Whenthelengthismeasuredasthedistancebetweencentersoftwoengravedlines,itiscalled
linestandard.
•Bothmaterialstandardsyardandmeterarelinestandards.
•Themostcommonexampleoflinemeasurementsistherulewithdivisionsshownaslines
markedonit.

4. Characteristics of Line Standard
1.Scalescanbeaccuratelyengravedbuttheengravedlinesthemselvespossessthicknessanditisnot
possibletotakemeasurementswithhighaccuracy.
2.Ascaleisquickandeasytouseoverawiderangeofmeasurements.
3.Thescalemarkingsarenotsubjectedtowear.However,theleadingendsaresubjectedtowearandthis
mayleadtoundersizemeasurements.
4.Ascaledoesnotpossessa‘builtin’datumwhichwouldalloweasyscalealignmentwiththeaxisof
measurement,thisagainresultsin‘undersizing’.
5.Scalesaresubjectedtoparallaxeffect,whichisasourceofbothpositive&negativereadingerrors’
6.Also,theassistanceofmagnifyingglassormicroscopeisrequiredifsufficientaccuracyistobe
achieved.

5. End Standard
•Endstandard-Whendistanceismeasuredbetweentwoparallelflatsurfaces.
•Examples:Slipgauges,AnvilsofMicrometer,etc
•Theendfacesarehardened,lappedflatandparalleltoaveryhighdegreeofaccuracy.

6. Characteristics of End Standard
•Endstandardsarehighlyaccurateandarewellsuitedformeasurementsofclosetolerancesas
smallas0.0005mm.
•Theyaretimeconsuminginuseandproveonlyonedimensionatatime.
•Endstandardsaresubjectedtowearontheirmeasuringfaces.
•Endstandardshavea‘builtin’datum,becausetheirmeasuringfacesareflat&parallelandcan
bepositivelylocatedonadatumsurface.
•Theyarenotsubjectedtotheparallaxeffectsincetheirusedependson“feel”.
•Groupofslipscanbe"wrung"togethertobuildupagivensize;faultywringingandcarelessuse
mayleadtoinaccurateresults.

7. Comparison b/w Line & End Standard

8. Thank you