Prismatic Straight Triangular Edges that are used for checking angle and flatness of machine tools dovetailed guide ways, fixtures and slides. Triangular straight edge, two faces are scrapped and angle between the scrapped faces (30 or 45 or 60 Degree) is accurately processed. The third side is painted and recessed for weight reduction in the bigger sizes.

Prismatic Straight Triangular Edges

Standard Size and accuracy of Luthra Triangular Straight Edges as per IS : 8823-1978, Grade-1:

Angle between working Surfaces (in Degrees)
Tolerance on Flatness of
Working Surfaces
30 45 60

Microns (um)
Width of working surfaces (mm)
500 70 70 60
750 90 90 80
1000 110 110 100
1250 130 130 110
1500 130 130 110
2000 130 130 110

Features Of Prismatic Straight Triangular Edges

  • Luthra cast iron Prismatic Straight Edges are made of good quality closed grain cast iron strictly as per IS 210:1993 confirming to Grade FG-220.Castings are stress relieved either by natural ageing or by artificial seasoning.
  • Working surfaces are finished by hand scrapping to desired accuracy as per IS 8823:1978.
  • Provided with suitable M.S. handles on both end for easy lifting.
  • Offered in sizes with various working angles between working faces as shown in the table.
  • Prismatic Straight edges are supplied with computerized calibration certificate traceable to National Physical Laboratory (NPL, Govt of India) New Delhi.