Squares, Protractors and Spirit levels

Squares according to DIN 875

This standard is valid for flat squares (design A), back squares (design B) and bevel edge squares (design C), of steel with a 90° angle and a leg length up to 1500 mm.

Angle tolerances
The calculation is done according to the formulas given in the table; the tolerances are rounded off. Equal values are applicable for the parallelism of the measuring surfaces to one another.

L = Leg lengths L1 or L2

Length L = mm	Grade 00 (2 + L/100)μm	Grade 0 (5 + L/50)μm	Grade 1 (10 + L/20)μm	Grade 2 (20 + L/10)μm
50	3	-	-	-
75	3	7	14	28
100	3	7	15	30
150	4	8	18	35
200	4	9	20	40
250	5	10	23	45

300	5	11	25	50
400	-	13	30	60
500	-	15	35	70
600	-	17	40	80
750	-	20	43	85
1000	-	25	60	120
1500	-	35	85	170

The flatness of the test surfaces and/or straightness of the bevelled edge are calculated using the following formulas:

L = Leg lengths L1 or L2

Grade	Formula
00	(2 + L/250)μm
0	(2 + L/100)μm
1	(4 + L/50)μm
2	(8 + L/25)μm

Calibration:
Calibration certificates are issued for all squares.