Threadcheck Catolog

FIXED LIMIT GAGE FACT SHEET

GAGEMAKER'S TOLERANCE CHART

RANGE

XXXX

XXX

.0009" to.8250"

.000005"

.00001"

.00002"

.00004"

.00007"

.0001"

.00020"

.8251" to 1.5100"

.000008"

.000015"

.00003"

.00006"

.00009"

.00012"

.00024"

1.5101" to 2.5101"

.00001"

.00002"

.00004"

.00008"

.00012"

.00016"

.00032"

2.5101" to 4.5100"

.000013"

.000025"

.00005"

.00010"

.00015"

.00020"

.00040"

4.5101" to 6.5100"

.000017"

.000033"

.000065"

.00013"

.00019"

.000250"

.00050"

6.5101" to 9.0100"

.00002"

.00004"

.00008"

.00016"

.00024"

.000320"

.00064"

9.0101" to 12.260"

.000025"

.00005"

.0001"

.0002"

.0003"

.000400"

.00080"

METRIC EQUIVALENTS

RANGE

.74mm to 20.96mm

.00051

.00102

.00178

.00254

.005

20.96mm to 38.35mm

.00076

.00152

.00229

.00305

.006

38.35mm to 63.75mm

.00102

.00203

.00305

.00406

.008

63.75mm to 114.55mm

.00127

.00254

.00381

.00508

.010

114.55mm to 163.35mm

.00165

.00330

.00483

.00635

.013

165.35mm to 228.85mm

.00203

.00406

.00610

.00813

.016

228.85mm to 311.40mm

.00254

.00508

.00762

.01016

.020

TOLERANCE DIRECTION

Fixed limit gages are primarily used to check

Type of Gage

GO Member

NOGO Member

dimensions and geometries. Plug gages check

Thread plug

Plus

Minus

internal dimensions and ring gages check external

dimensions. Inspection is performed by use of

Plain plug

Plus

Minus

GO/NOGO gages that represent the Minimum and

Thread ring gage

Minus

Plus

Maximum limit of the product part characteristic

Plain ring gage

Minus

Plus

to ensure assembleability and fit. This method is

Thread Setting Plug

Minus

Plus

used for both thread gages and cylindrical plain

When ordering gages, the two basic principles are:

gages.

1. Do not allow the tolerance of the GO and NOGO gages to consume more

GO gages passing through a part assure that the

than 10% of your product tolerance. The 10% is usually divided

maximum material condition of a part has not

equally between the GO and NOGO gages.

been exceeded. NOGO gages not passing through

2. Higher precision gages will accept slightly more product but with less

the part assure the dimension has not dropped

wear life and greater expense.

below the minimum material condition.

PROPER CARE AND USAGE OF GAGES

Fixed limit gages are highly accurate, easy to use,

and economical.

� Partindimensions to be gaged should be cleaned and burr free to prevent

HOW TO DETERMINE AND SELECT

gaging interference.

THE PROPER TOLERANCE FOR

� Gages should be turned or pushed slowly and gently into or onto the dimension being checked.
Forcing gages will result in faulty gaging and

YOUR GAGING APPLICATION

the possibility of damaging both the part and gage.

The normal rule of practice requires 10% of

�

The effects of thermal expansion should be taken into consideration on

product tolerance to be divided between the

both the part and the gage. The temperature of the part and the gage

" GO "and" NOGO " gages. For plug gages, a plus

should be the same. 68� F is the ideal temperature at which both part

tolerance is applied to the GO member

and gage should be at when inspected because gages are calibrated at

and a minus tolerance to the NOGO member. Ring

68� F. This effectively eliminates any error due to thermal expansion.

gages receive reverse tolerance direction so that

�

Protecting gages from excessive heat, moisture and corrosive chemicals

the " GO " member is minus and the

will extend the life of your gages. After use, gages should be cleaned and

" NOGO " is plus tolerance. Applying this

recoated with a thin-film rust preventative and stored properly.

practice results in gage tolerance always being

�

Gages should be periodically inspected and calibrated to assure accuracy.

included in the part tolerance by up to 10%.

Go member gages tend to wear quicker with normal use. NOGO gages will

This results in the possibility that 10% of good

wear on the ends that receive the greatest usage. Frequency of inspection

product could fail inspection but that no bad

and calibration should be dependent on such factors as the amount of

product would ever pass.

usage, part and gage material, tolerance, and quality procedures.

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