Centre Punch: Difference between revisions
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[[File:CentrePunch.png|300px|right]] | [[File:CentrePunch.png|300px|right]] | ||
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=====Description===== | =====Description===== | ||
[https://en.wikipedia.org/wiki/Punch_(tool)#Centre '''Centre Punches'''] are ground to a strong point with an included angle of 90 degrees ''(in a similar manner to a '''[[Scriber]]''')''. | |||
[https://en.wikipedia.org/wiki/Punch_(tool)#Centre '''Centre Punches'''] are ground to a strong point with an included angle of 90 degrees by holding them '''[[Tangents and Normals|Tangentially]]''' to a '''[[Tool Grinder]]''' and rotating them. This tends to create grinding marks which run along the point and strengthen it rather than weakening it by going across ''(i.e. in a similar manner to a '''[[Scriber]]''')''. | |||
=====Features and Uses===== | =====Features and Uses===== | ||
To stop a drill bit skidding about a metal surface, these are used to make a small indentation to locate the drill centre. | To stop a drill bit skidding about a metal surface, these are used to make a small indentation to locate the drill centre. | ||
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Revision as of 08:36, 9 February 2017
Description
Centre Punches are ground to a strong point with an included angle of 90 degrees by holding them Tangentially to a Tool Grinder and rotating them. This tends to create grinding marks which run along the point and strengthen it rather than weakening it by going across (i.e. in a similar manner to a Scriber).
Features and Uses
To stop a drill bit skidding about a metal surface, these are used to make a small indentation to locate the drill centre.
Note: Hold the punch to an angle to position on centre then raise to the vertical and strike it sharply with a hammer - but only once - striking several times may cause the punch to bounce around.
- The lowest cost option is to use a hand-held punch with a hammer but a wide range of automatic punches are available - both Dot Punches and Centre Punches.
- In general, Dot Punches have a sharper point (i.e. 60° instead of 90°) and need only the lower ranges of impact force (e.g. 20N to 50N).
- Automatic punches are simply pushed down against the work-piece and do not need to be struck - indeed, should NOT be struck with a hammer.
 
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| Centre Punch
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Automatic Centre Punch
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Bell Centre Punch
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Nail Punch
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Pin Punch
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Hollow Punch Set
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Number and Letter Punch Set
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