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1.260”						Hole
										R
1.254”

1.760”

1.754”

4.Design GO/NO GO gauges for an equilateral triangular hole that is to have each side 2.025”±0.002”.

ANSWERS:

1.(ans. GO limits are 1.50025”/1.5000” dia., NO GO limits are 1.50250”/1.50225” dia.)

2.(ans. GO limits are 0.8746”/0.8738” dia., NO GO limits are 0.8678”/0.8670” dia.)

3.(ans. the three gauges are pictured below)

GO gauge

1.2549”

1.2543”

2.3819”

2.3813”

2.3900”

2.3891”

NO GO gauge

GO		1.2600”
		1.2594”
NO

35.6.7 Sine Bars

•When a reference for a non-square angle is required, a sine bar can be used.

•Basically a sine bar is a bar of known length. When gauge blocks are placed under one end, the sine bar will tilt to a specific angle.

•The figure below shows a sine bar from the side,

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hardened and ground bar

l

	h
gauge blocks	h
θ

surface plate

hardened and ground cylinders

l = distance between centres of ground cylinders (typically 5” or 10”) h = height of the gauge blocks

θ = the angle of the plate

θh

=asin --l

•A simple example is - set up a sine bar with an angle of 24°-57’, if the sine bar has 5” centres.

sin		24 +	57	=	h
			60-----		5.000------------
h		= 2.1091 inches

continue on and calculate the gauge blocks required......

• The sine bar shown above will only allow a single angle to be set, but in some cases we want to