zerogage - Depth Gages Depth Gages
 
Engineering & Manufacturing Standards

Customer designs utilizing Zero blanks usually designate the manufacturing tolerances of the finish-grind dimensions. When these tolerances are not shown, or if Zero Gage is doing the design, the generally accepted practice is to use 10% or less of the part tolerance for manufacturing. This manufacturing tolerance is usually divided equally between the set dimensions to control the linear movement of the gage pin. Tolerances will be directed toward mean with a plus or minus sign. Use of this method assures that the gage will not accept an out-of-tolerance part.

DEPTHS: EXAMPLES 1 and 2 are typical set-up dimensions, where 10% of the part tolerance is split between range and step (note that the GAGE RANGE tolerance has been subtracted from the step dimensions, and that the step always has a minus tolerance). EXAMPLE 3 is an exception to the standard practice of equally splitting tolerances because a long pin is used. This allows minimum cost of altering the blank.

No. 1 & No. 2
Part Depth
.520 - .530

No. 3
7.130
7.140
Part Depth

NO. 1
NO. 2
NO. 3
ROLL DIMENSIONS FOR COUNTERSINK DIAMETERS.
If the countersink diameter is not furnished, but instead is shown as a depth, we use the MEAN HOLE SIZE and MEAN ANGLE to calculate the countersink diameter. The roll chart on next page is used to calculate the roll and step dimensions. The reference dimension or length the pin protrudes from the barrel body should be a little smaller than the roll diameter to aid manufacturing setup.
PART INFO
.
550 - .590 C.TSK DIA.
60° INCL. ANGLE
.125 ROLL DIA.
.550 MIN
.1971 ROLL CHART
.7471 MIN.
.590 MAX.
.1971 ROLL CHART
.7871 MAX.
N0. 4
N0. 5
STEP DIM. = .590 - .550 = .040 X .86603 (ROLL CHART CONSTANT) = .0346
DRILL HOLE DEPTHS: Some customers prefer to check drilled hole depths using the sharp edge or gage pin to set up the gage depth. Example 1: Because of corner breakdown, others prefer to set pin up using the drill point angle to register against Example 2.
PART CONDITION
EXAMPLE 1
EXAMPLE 2
  EXAMPLE No. 2 ONLY .5100 MIN. DEPTH
.0937 ROLL SIZE
.6037 SET DIM.
.501 USE MEAN HOLE SIZE
.1197 FROM ROLL CHART
.6207 ROLL DIM.