Types and Features of Gauges

• Gauge block
• Feeler gauge
• Feeler gauge (thickness gauge)
• Tapered gauge
• Welding gauge
• Center gauge
• Angle gauge
• Radius gauge
• Pitch gauge
• Chamfer gauge

Gauge block

Reference instrument for the “length” used in inspecting the accuracy of measuring instruments and testing machine parts, tools, etc.
Major materials: Steel, ceramic, etc.

Features

• This is a length reference end measure made of durable material, rectangular in cross section, and having two parallel measuring faces with the property of adhering well to the reference plane.

Gauge blocks are used to test the accuracy of measuring instruments. Gauge blocks are used to inspect the accuracy of micrometers.

Combination of required dimensions

Rotate the center of the two measuring faces 90° and overlap them to make them in close contact with each other.

If there is no gauge block that exactly matches the required dimensions, more compact gauge blocks can be combined to make the required dimensions. In that case, please be careful of the following.

1. 1.Minimize the number of combination pieces.
2. 2.The combination should be selected according to the last digit.
3. 3.Although there are many possible combinations of integral parts, avoid using only the same gauge block as much as possible, considering wear.

Main points

• Check the nominal dimensions (mm).
  The larger the number of pieces in the set, the fewer the number of combination pieces per dimension and the more combinations can be used, which leads to maintaining accuracy and reducing damage.
• Check the class according to the intended use.
• Check whether it is made of steel or ceramic.

Purpose of use		Class
For construction	Attachment of cutting tool	2
	Fabrication of gauges; adjusting sensitivity of measuring instruments	1 or 2
For testing	Testing of machine parts, tools, etc.	1 or 2
	Gauge accuracy inspection, accuracy adjustment of measuring instruments	0 or 1
For standard	Construction and testing; inspection of accuracy of gauge blocks; inspection of measuring instruments	K or 0
For reference	Inspection of accuracy of standard gauge blocks; academic research	K

Feeler gauge

This tool is used to measure the dimensions of narrow gaps that cannot be measured with other measuring instruments.

A long, thin metal plate is stored in a case.
It can be used by cutting only the necessary amount with metal cutting scissors, etc., or it can be used and returned without cutting.

This is used for assembly and adjustment of automobile engines and other internal combustion equipment, and it is useful for continuous measurement of individual gaps.

Useful info : Measures gaps

Generally, the above names are used interchangeably, but collectively, tools for measuring gaps are called “feeler gauges” in English.

[Cautions]
When cutting and using the gauge, be sure to grind the cut end with a fine grinding wheel to remove burrs and gouges before use.

Main points

• Check the thickness dimensions (mm).
  
  • They may be 0.005 mm to 1.000 mm.
• Check the feeler gauge length (m). (ordinarily 1 m reel)

Feeler gauge (thickness gauge)

This tool is used to measure the dimensions of the gap between two surfaces.

• Each plate of a feeler gauge is called a leaf. The thickness accuracy of the leaf is divided into JIS standard precision products and general products according to the rank of the thickness accuracy of the leaf. The allowable range of thickness accuracy for JIS standard products is approx. 1/2 to 1/3 of that for general products, which is stricter accuracy and more in line with the strict demands of the times.

Features

• Thickness accuracy differs depends on the thickness of each leaf. Using a single leaf as much as possible, without combining two together, is recommended. (Accuracy becomes poor when combined.)
• There are two types of leafs depending on the shape of the tip.

Usage examples

• For measuring the gap between a machine and its installation base when installing a machine or other equipment.
• For measuring the gap between the moving and static parts of motors and engines.
• For gap measurement between various doors or lids and the main body.

Method of use

Insert a leaf horizontally into the gap. If it does not fit, do not force it in; rather, use a leaf of smaller thickness. Conversely, if it enters too easily, use a leaf of greater thickness.

Method of maintenance

It is important to wipe the surface clean with deerskin, etc., before use, and to apply rust-prevention powder or oil for measuring tools thoroughly after use to prevent rust from occurring.

Useful info : Feeler gauge standard

■ JIS standard leaf accuracy

(Unit: mm)

Thickness dimensional classification	Thickness dimensional tolerance	Width warpage tolerance
0.01 - 0.06	± 0.003	―
0.07 - 0.10	± 0.004	―
0.11 - 0.35	± 0.005	―
0.36 - 0.65	± 0.008	0.004
0.66 - 3.00	± 0.010	0.005

Remarks: Values in this table are those at 20°C.

[Cautions]
Clean and inspect before use, making sure surfaces are free of dirt, rust, and scratches. Abnormalities on the leaf surface, i.e., the measuring face, can cause errors.

Main points

• Check the length (mm). (The standard leaf width is 12.7 mm.)
• Check the measurement range (combination of thicknesses) (mm) that fits the gap.

Tapered gauge

This tool uses the gauge surface (tapered) to measure gaps and hole diameters.

Thickness taper	Width taper	Cylindrical taper
This gauge uses the thickness taper to measure gaps.	Gaps are measured using the width taper.	Measures hole diameter or gaps.

Select the type of gauge according to the point to be measured.

Method of use

<Measuring gaps>
When measuring gaps, gauge thickness (surface contact) measurement is more reliable.

<Measuring hole diameter>
For inner diameter measurement, cylindrical types are more reliable. Measurement errors occur with other types.

Main points

• Select the type of gauge that best suits the application.
• Check the measurement range (mm).

Welding gauge

This compact tool can perform a variety of welding-related measurements with a single gauge.

Features

• Designed to be compact enough to fit in a pocket, it is especially effective in environments such as on high scaffolding.
• This is a multi-functional type gauge for a wide range of measurements required for welding.

Measurement points

■ General use / General high-precision use

• Measuring dimensions of excess metal
  
• Measuring pre-weld machining
  
• Application measurement
  

■ General undercut use

Main points

• Select the size and model according to the point to measure.

Center gauge

This tool is used to test the angle of tool (bite) blades when threading on a lathe.

Features

• This is used to install the tool bit blade for threading at a right angle to the workpiece when threading on a lathe.

Method of use

By using a center gauge, the tool bit can be easily mounted at a right angle to the workpiece.

If both match perfectly, the blade is attached at a right angle.

Main points

• Check whether the tool is for millimeters or inches.
• Check whether the blade angle is 55° or 60°.

Angle gauge

This tool is used for testing the angle of workpieces.

Features

• Internal angle testing, which is more difficult to measure than general external angle testing, can be easily performed.

Method of use

Comparative measurement is made by placing the gauge part on the angle part to be measured.
The angle engraved on the gauge is the complementary angle (the difference from 90°). For a 10° gauge, the gauge itself has an angle of 80° (temporary angle) and 100° (supplementary angle).

Example) Gauge with 10° engraved
Bottom part angle is 80°.
Top part angle is 100°.

Display angle

Gauge display angles are as follows.
1°、2°、3°、4°、5°、7°、8°、9°、10°、12°、14°、14 1/2°、15°、20°、25°、30°、35°、45°

Main points

• Check the display angles.
  * The angle engraved is the difference from 90°, not the angle of the gauge itself.

Radius gauge

This gauge is used for dimensional testing of the radius (curved part) of workpieces, dies, wood blocks, etc.

For round radius
Suitable for measuring round radius (outer diameter of pipes, teacups, etc.).

For angular radius
Suitable for measuring angular radius (corners of desks, boxes, etc.).

For both round and angular radius
Both round and angular radius can be measured.

Features

• The dimensions of curved sections (R) that cannot be measured with general measuring instruments such as vernier calipers and rulers can be quickly read.
• Place the gauge on the curved section of the object to be measured and read the dimension visually.
  Place the gauge on the curved section and read the dimension.

Main points

• Check the shape.
• Depending on the curve shape, select a radius gauge for round radius (1/2 circle), angular radius (1/4 circle), or both round and angular radius and that is appropriate for the size.
• Select the number of increments (size) of the gauge’s scale.

Pitch gauge

This is a tool to check the pitch of general screws.

Features

For general screws, there are three standards of millimeter, Whitworth, and unified, and use the pitch gauges that are mainly used in Japan.
Place a pitch gauge on a screw of unknown size, and visually read the pitch of that screw.

• The gauge has the pitch size of threads engraved on it for easy reading.

• The numbers engraved indicate the distance from thread to thread for millimeter specification type, and the number of threads in 1 inch (25.4 mm) for inch specification type.

Main points

• Check whether the tool is for millimeters or inches.
• Check the angle.

	Display	Angle
For millimeters	mm	60°
For inches	Number of threads	55°
		60°

Chamfer gauge

This tool is used to measure the size of the chamfer edge after chamfering.

• A square (cube) shaped workpiece is fixed to the lathe and it can be measured while fixed after grinding with a blade.

• Curved surfaces can also be measured. However, the person measuring must judge the surface shape visually.

Features

• Accurate chamfer measurement can be done easily and quickly.

Method of use

• A recess (slit) is provided at the 0 point to allow measurement even for small surfaces.

• Measurement can be done even without chamfering.

Useful info What is chamfer?

A chamfer edge, represented by C, is a 90° corner with a 45° chamfered area.

Main points

• Check the measurement range (mm).

PDF list