Specialist marking tools

Marking/Cutting/Mortise gauge:

• Used to mark/dent a piece of timber parallel to the edge

Odd leg callipers:

• Used to mark a line on an edge/step on a peice of metal

Internal callipers:

• Used to measure the internal diameter of a tube/pole

External callipers:

• Used to measure the outsude diameter of a tube/pole

Try-square:

• Used to mark a line 90^o to a piece of timber

Engineering square:

• Used to mark a line 90^o to a piece of metal

Micrometre:

• Used to measure a small distance/thickness between its tqo faces, one face can be moved to measure different distances

Vernier callipers:

• Used to measure internal/external measurements very orecisely

Densitometer:

• A machine which can be used to measure the optical density of a photographic/semi-transparent material

Dividers:

• Used to mark circles/curves on a piece of metal

Jigs:

• A jig is used to control the motion of a tool

Advantages	Disadvantages
Increase rate of production Allow for repeatable accuracy Requires little skill to use	Jig must be bought/created before it can be used Only suitable for low volume/batch production

Fixtures:

• Used to support/hold the workpiece in place

Advantages	Disadvantages
Increase rate of production Allow for repeatable accuracy	Former must be bought/created before it can be used Only suitable for low volume/batch production

Go-no-go gauge:

• A go-no-go gauge is a tool used to check a piece of work is the correct size against its allowable tolerance

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