Twist Drills - Revision history

DT Online at 19:10, 20 August 2016

2016-08-20T19:10:34Z

← Older revision		Revision as of 19:10, 20 August 2016
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	[[File:TwistDrillSet.png\|250px\|right]]		[[File:TwistDrillSet.png\|250px\|right\|link=http://www.amazon.co.uk/gp/product/B009K1S3ZY/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=B009K1S3ZY&linkCode=as2&tag=dton06-21]]
	__TOC__		__TOC__


	=====Description=====		=====Description=====

	[https://en.wikipedia.org/wiki/Drill_bit '''Twist Drills'''] are the most commonly used drill bit and are suitable for drilling most materials including [https://en.wikipedia.org/wiki/Carbon_steel#Mild_and_low-carbon_steel '''Mild Steel''']. They are more completely known as '''Morse Twist Drills''', named after the American Engineer, [http://www.morsecuttingtools.com/cgi/CGP2CSGEN?PAHDID=000000112731547&PARDID=316332221178492&PMSIDE=Y&PMFILE=MS2ABOUT01.html '''Stephen A. Morse'''] who first developed them in 1864.		[https://en.wikipedia.org/wiki/Drill_bit '''Twist Drills'''] are the most commonly used drill bit and are suitable for drilling most materials including [https://en.wikipedia.org/wiki/Carbon_steel#Mild_and_low-carbon_steel '''Mild Steel''']. They are more completely known as '''Morse Twist Drills''', named after the American Engineer, [http://www.morsecuttingtools.com/cgi/CGP2CSGEN?PAHDID=000000112731547&PARDID=316332221178492&PMSIDE=Y&PMFILE=MS2ABOUT01.html '''Stephen A. Morse'''] who first developed them in 1864.
	[[File:TwistDrills.png\|250px\|right]]		[[File:TwistDrills.png\|250px\|right]]


	=====Features and Uses=====		=====Features and Uses=====

	Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills may have a reduced diameter shank to fit into '''[[Portable Electric Drills]]''' or can have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which fits directly into the hollow spindle of a '''[[Drill Press\|Bench Drill]]''', '''[[Drill Press\|Pedestal Drill]]''' or '''[[Centre Lathe\|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.		Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills may have a reduced diameter shank to fit into '''[[Portable Electric Drills]]''' or can have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which fits directly into the hollow spindle of a '''[[Drill Press\|Bench Drill]]''', '''[[Drill Press\|Pedestal Drill]]''' or '''[[Centre Lathe\|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.

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	</span>		</span>
	----		----

	=====Maintenance and Manufacture=====		=====Maintenance and Manufacture=====

	[[File:TwistDrill.png\|400px\|right]]		[[File:TwistDrill.png\|400px\|right]]
	Twist Drills can be sharpened using a '''[[Tool Grinder\|Bench Grinder]]''' and are usually ground to a '''Cutting Angle''' of 59° to its axis for general work ''(to create a '''Point Angle''' of 118°)'' but this can vary for hard or soft materials ''(e.g. 45° is more suitable for [https://en.wikipedia.org/wiki/Cast_iron '''Cast Iron'''] and [https://en.wikipedia.org/wiki/Brass '''Brass'''])''.		Twist Drills can be sharpened using a '''[[Tool Grinder\|Bench Grinder]]''' and are usually ground to a '''Cutting Angle''' of 59° to its axis for general work ''(to create a '''Point Angle''' of 118°)'' but this can vary for hard or soft materials ''(e.g. 45° is more suitable for [https://en.wikipedia.org/wiki/Cast_iron '''Cast Iron'''] and [https://en.wikipedia.org/wiki/Brass '''Brass'''])''.
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	=====Dowel Bits=====		=====Dowel Bits=====
	[[File:DowelBits.png\|250px\|right]]
			[[File:DowelBits.png\|250px\|right\|link=http://www.amazon.co.uk/gp/product/B0001P19BI/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=B0001P19BI&linkCode=as2&tag=dton06-21]]

	Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] tearing and leaving a rough edge to the hole. [https://en.wikipedia.org/wiki/Drill_bit#Lip_and_spur_drill_bits '''Dowel Bits'''] ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] to ensure clean, straight holes.		Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] tearing and leaving a rough edge to the hole. [https://en.wikipedia.org/wiki/Drill_bit#Lip_and_spur_drill_bits '''Dowel Bits'''] ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] to ensure clean, straight holes.

DT Online: Added Template

2016-05-16T11:32:48Z

Added Template

← Older revision		Revision as of 11:32, 16 May 2016
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	[[File:TwistDrillSet.png\|~~150px~~\|right]]		[[File:TwistDrillSet.png\|250px\|right]]
			__TOC__

			=====Description=====
	[https://en.wikipedia.org/wiki/Drill_bit '''Twist Drills'''] are the most commonly used drill bit and are suitable for drilling most materials including [https://en.wikipedia.org/wiki/Carbon_steel#Mild_and_low-carbon_steel '''Mild Steel''']. They are more completely known as '''Morse Twist Drills''', named after the American Engineer, [http://www.morsecuttingtools.com/cgi/CGP2CSGEN?PAHDID=000000112731547&PARDID=316332221178492&PMSIDE=Y&PMFILE=MS2ABOUT01.html '''Stephen A. Morse'''] who first developed them in 1864.		[https://en.wikipedia.org/wiki/Drill_bit '''Twist Drills'''] are the most commonly used drill bit and are suitable for drilling most materials including [https://en.wikipedia.org/wiki/Carbon_steel#Mild_and_low-carbon_steel '''Mild Steel''']. They are more completely known as '''Morse Twist Drills''', named after the American Engineer, [http://www.morsecuttingtools.com/cgi/CGP2CSGEN?PAHDID=000000112731547&PARDID=316332221178492&PMSIDE=Y&PMFILE=MS2ABOUT01.html '''Stephen A. Morse'''] who first developed them in 1864.
	[[File:TwistDrills.png\|~~200px~~\|right]]		[[File:TwistDrills.png\|250px\|right]]


			=====Features and Uses=====
	Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills may have a reduced diameter shank to fit into '''[[Portable Electric Drills]]''' or can have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which fits directly into the hollow spindle of a '''[[Drill Press\|Bench Drill]]''', '''[[Drill Press\|Pedestal Drill]]''' or '''[[Centre Lathe\|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.		Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills may have a reduced diameter shank to fit into '''[[Portable Electric Drills]]''' or can have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which fits directly into the hollow spindle of a '''[[Drill Press\|Bench Drill]]''', '''[[Drill Press\|Pedestal Drill]]''' or '''[[Centre Lathe\|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.

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	</span>		</span>
	----		----

	~~__TOC__~~


	=====Maintenance and Manufacture=====		=====Maintenance and Manufacture=====
	[[File:TwistDrill.png\|400px\|right]]		[[File:TwistDrill.png\|400px\|right]]
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	=====~~[https://en.wikipedia.org/wiki/Drill_bit#Lip_and_spur_drill_bits~~ Dowel Bits]=====		=====Dowel Bits=====
	[[File:DowelBits.png\|~~200px~~\|right]]		[[File:DowelBits.png\|250px\|right]]

	Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] tearing and leaving a rough edge to the hole. '''Dowel Bits''' ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] to ensure clean, straight holes.		Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] tearing and leaving a rough edge to the hole. [https://en.wikipedia.org/wiki/Drill_bit#Lip_and_spur_drill_bits '''Dowel Bits'''] ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] to ensure clean, straight holes.


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	~~=====Masonry Bits=====~~		{{Twist Drill Buyers Guide}}
	~~[[File:MasonryBits.png\|200px\|right]]~~

	These are used mainly with '''[[Portable Electric Drills]]''' with a [https://en.wikipedia.org/wiki/Hammer_drill '''Hammer Action'''] and have a [https://en.wikipedia.org/wiki/Tungsten_carbide '''Tungsten Carbide Tip'''] to penetrate masonry such as brick, concrete and stone. Drills intended for heavier work may be designed for use with an '''[[Portable Electric Drills\|SDS Drill~~]]''' and have tips able to withstand the constant hammering action.~~


	They are normally replaced rather than sharpened but, if sharpening is required, this must be done using a '''Green Grit''' ''(i.e. [https://en.wikipedia.org/wiki/Silicon_carbide#Abrasive_and_cutting_tools '''Silicon Carbde''']) grinding wheel.


	[[Category:Drilling and Boring]]		[[Category:Drilling and Boring]]

DT Online: Corrected Link

2016-05-14T14:14:09Z

Corrected Link

← Older revision		Revision as of 14:14, 14 May 2016
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	[[File:CentreDotPunching.png\|100px\|right]]		[[File:CentreDotPunching.png\|100px\|right]]
	<span style="color: green">'''Note:'''		<span style="color: green">'''Note:'''
	For accurate drilling through harder and smoother surfaced materials such as steel, hole centres should be marked with a '''[[Punches\|Centre Punch]]''' and when extreme precision is required, the hole diameter should be scribed with '''[[Dividers and Compasses\|Dividers]]''' and its intersections with the two axes marked with a '''[[Punches\|Dot Punch]]''' - an accurately drilled or bored hole would cut each of the dot punched marks in two!		For accurate drilling through harder and smoother surfaced materials such as steel, hole centres should be marked with a '''[[:Category:Punches\|Centre Punch]]''' and when extreme precision is required, the hole diameter should be scribed with '''[[Dividers and Compasses\|Dividers]]''' and its intersections with the two axes marked with a '''[[:Category:Punches\|Dot Punch]]''' - an accurately drilled or bored hole would cut each of the dot punched marks in two!
	</span>		</span>
	----		----

DT Online: Added link

2016-02-08T08:59:15Z

Added link

← Older revision		Revision as of 08:59, 8 February 2016
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	[[File:DowelBits.png\|200px\|right]]		[[File:DowelBits.png\|200px\|right]]

	Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the ~~grain~~ tearing and leaving a rough edge to the hole. '''Dowel Bits''' ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the ~~grain~~ to ensure clean, straight holes.		Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] tearing and leaving a rough edge to the hole. '''Dowel Bits''' ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the [https://en.wikipedia.org/wiki/Wood_grain '''Grain'''] to ensure clean, straight holes.

DT Online: Corrected links

2015-11-08T09:56:01Z

Corrected links

← Older revision		Revision as of 09:56, 8 November 2015
Line 4:		Line 4:


	Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills may have a reduced diameter shank to fit into '''[[Portable Electric Drills]]''' or can have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which fits directly into the hollow spindle of a '''[[Bench Drill]]''', '''[[Pedestal Drill]]''' or '''[[Centre Lathe\|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.		Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills may have a reduced diameter shank to fit into '''[[Portable Electric Drills]]''' or can have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which fits directly into the hollow spindle of a '''[[Drill Press\|Bench Drill]]''', '''[[Drill Press\|Pedestal Drill]]''' or '''[[Centre Lathe\|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.

DT Online: Added Image

2015-10-27T23:29:58Z

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← Older revision		Revision as of 23:29, 27 October 2015
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	----		----
			[[File:CentreDotPunching.png\|100px\|right]]
	<span style="color: green">'''Note:'''		<span style="color: green">'''Note:'''
	For accurate drilling through harder and smoother surfaced materials such as steel, hole centres should be marked with a '''[[Punches\|Centre Punch]]''' and when extreme precision is required, the hole diameter should be scribed with '''[[Dividers and Compasses\|Dividers]]''' and its intersections with the two axes marked with A '''[[Punches\|Dot Punch]]''' - an accurately drilled or bored hole would cut each of the dot punched marks in two!		For accurate drilling through harder and smoother surfaced materials such as steel, hole centres should be marked with a '''[[Punches\|Centre Punch]]''' and when extreme precision is required, the hole diameter should be scribed with '''[[Dividers and Compasses\|Dividers]]''' and its intersections with the two axes marked with a '''[[Punches\|Dot Punch]]''' - an accurately drilled or bored hole would cut each of the dot punched marks in two!
	</span>		</span>
	----		----

DT Online: Added Images and text

2015-10-27T20:31:08Z

Added Images and text

← Older revision		Revision as of 20:31, 27 October 2015
Line 4:		Line 4:


	Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills ~~often~~ have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which ~~fit~~ directly into the ~~drill~~ spindle or '''[[Centre Lathe\|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.		Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills may have a reduced diameter shank to fit into '''[[Portable Electric Drills]]''' or can have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which fits directly into the hollow spindle of a '''[[Bench Drill]]''', '''[[Pedestal Drill]]''' or '''[[Centre Lathe\|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.


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	</span>		</span>
	----		----

			__TOC__


			=====Maintenance and Manufacture=====
	[[File:TwistDrill.png\|400px\|right]]		[[File:TwistDrill.png\|400px\|right]]
			Twist Drills can be sharpened using a '''[[Tool Grinder\|Bench Grinder]]''' and are usually ground to a '''Cutting Angle''' of 59° to its axis for general work ''(to create a '''Point Angle''' of 118°)'' but this can vary for hard or soft materials ''(e.g. 45° is more suitable for [https://en.wikipedia.org/wiki/Cast_iron '''Cast Iron'''] and [https://en.wikipedia.org/wiki/Brass '''Brass'''])''.
	Twist Drills are usually ground to a '''Cutting Angle''' of 59° to its axis for general work ''(to create a '''Point Angle''' of 118°)'' but this can vary for hard or soft materials ''(e.g. 45° is more suitable for [https://en.wikipedia.org/wiki/Cast_iron '''Cast Iron'''] and [https://en.wikipedia.org/wiki/Brass '''Brass'''])''.


	Most modern Twist Drills are manufactured from [https://en.wikipedia.org/wiki/High-speed_steel '''High Speed Steel (HSS)'''] and sometimes coated with [https://en.wikipedia.org/wiki/Titanium_nitride '''Titanium Nitride'''], for example, to harden the surface and give it a gold-coloured look. This is suitable for most materials but for drilling holes in masonry, a [https://en.wikipedia.org/wiki/Tungsten_carbide '''Tungsten Carbide Tip'''] is [https://en.wikipedia.org/wiki/Brazing '''Brazed'''] on.		Most modern Twist Drills are manufactured from [https://en.wikipedia.org/wiki/High-speed_steel '''High Speed Steel (HSS)'''] and sometimes coated with [https://en.wikipedia.org/wiki/Titanium_nitride '''Titanium Nitride'''] for example, to harden the surface and give it a gold-coloured look. This is suitable for most materials but for drilling holes in masonry, a [https://en.wikipedia.org/wiki/Tungsten_carbide '''Tungsten Carbide Tip'''] is [https://en.wikipedia.org/wiki/Brazing '''Brazed'''] on.


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	[[File:DowelBits.png\|200px\|right]]		[[File:DowelBits.png\|200px\|right]]

	Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the grain tearing and leaving a rough edge to the hole. '''Dowel Bits''' ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the grain to ensure clean, straight holes. They can often be made of [https://en.wikipedia.org/wiki/Carbon_steel#Higher-carbon_steels '''Carbon Steel'''] instead of '''HSS''' and, if so, are not suitable for use on harder metals but similar drills~~, with a 90° Point Angle,~~ can be used for ~~drlling~~ plastics and some softer metals such as '''Copper'''.		Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the grain tearing and leaving a rough edge to the hole. '''Dowel Bits''' ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the grain to ensure clean, straight holes.


			They can often be made of [https://en.wikipedia.org/wiki/Carbon_steel#Higher-carbon_steels '''Carbon Steel'''] instead of '''HSS''' and, if so, are not suitable for use on harder metals but similar drills can be used for drilling plastics and some softer metals such as [https://en.wikipedia.org/wiki/Copper '''Copper''']. Sharpening is best achieved using a file or the edge of a grinding wheel.


	=====Masonry Bits=====		=====Masonry Bits=====
	[[File:MasonryBits.png\|200px\|right]]		[[File:MasonryBits.png\|200px\|right]]

			These are used mainly with '''[[Portable Electric Drills]]''' with a [https://en.wikipedia.org/wiki/Hammer_drill '''Hammer Action'''] and have a [https://en.wikipedia.org/wiki/Tungsten_carbide '''Tungsten Carbide Tip'''] to penetrate masonry such as brick, concrete and stone. Drills intended for heavier work may be designed for use with an '''[[Portable Electric Drills\|SDS Drill]]''' and have tips able to withstand the constant hammering action.


			They are normally replaced rather than sharpened but, if sharpening is required, this must be done using a '''Green Grit''' ''(i.e. [https://en.wikipedia.org/wiki/Silicon_carbide#Abrasive_and_cutting_tools '''Silicon Carbde''']) grinding wheel.


			[[Category:Drilling and Boring]]

DT Online: Created Article

2015-10-27T19:20:24Z

Created Article

New page

[[File:TwistDrillSet.png|150px|right]]
[https://en.wikipedia.org/wiki/Drill_bit '''Twist Drills'''] are the most commonly used drill bit and are suitable for drilling most materials including [https://en.wikipedia.org/wiki/Carbon_steel#Mild_and_low-carbon_steel '''Mild Steel''']. They are more completely known as '''Morse Twist Drills''', named after the American Engineer, [http://www.morsecuttingtools.com/cgi/CGP2CSGEN?PAHDID=000000112731547&PARDID=316332221178492&PMSIDE=Y&PMFILE=MS2ABOUT01.html '''Stephen A. Morse'''] who first developed them in 1864.
[[File:TwistDrills.png|200px|right]]

Most '''Twist Drills''' have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Straight_shank '''Parallel Shank'''] and, for everyday use, come in sets covering [https://en.wikipedia.org/wiki/Drill_bit_sizes '''Drill Sizes'''] up to 13mm diameter. Larger diameter drills often have a [https://en.wikipedia.org/wiki/Drill_bit_shank#Morse_taper_shank '''Morse Taper Shank'''], ''(also named after Stephen A. Morse)'', which fit directly into the drill spindle or '''[[Centre Lathe|Lathe Tailstock]]''' for example. Drill lengths too can vary but the most common are the [https://en.wikipedia.org/wiki/Drill_bit_sizes#Jobber-length_drill '''Jobber'''] length of drill.

Whenever a large hole has to be drilled, it is good practice to first drill a smaller ''pilot hole'' to act as a guide.

----
<span style="color: green">'''Note:'''
For accurate drilling through harder and smoother surfaced materials such as steel, hole centres should be marked with a '''[[Punches|Centre Punch]]''' and when extreme precision is required, the hole diameter should be scribed with '''[[Dividers and Compasses|Dividers]]''' and its intersections with the two axes marked with A '''[[Punches|Dot Punch]]''' - an accurately drilled or bored hole would cut each of the dot punched marks in two!
</span>
----
[[File:TwistDrill.png|400px|right]]

Twist Drills are usually ground to a '''Cutting Angle''' of 59° to its axis for general work ''(to create a '''Point Angle''' of 118°)'' but this can vary for hard or soft materials ''(e.g. 45° is more suitable for [https://en.wikipedia.org/wiki/Cast_iron '''Cast Iron'''] and [https://en.wikipedia.org/wiki/Brass '''Brass'''])''.

Most modern Twist Drills are manufactured from [https://en.wikipedia.org/wiki/High-speed_steel '''High Speed Steel (HSS)'''] and sometimes coated with [https://en.wikipedia.org/wiki/Titanium_nitride '''Titanium Nitride'''], for example, to harden the surface and give it a gold-coloured look. This is suitable for most materials but for drilling holes in masonry, a [https://en.wikipedia.org/wiki/Tungsten_carbide '''Tungsten Carbide Tip'''] is [https://en.wikipedia.org/wiki/Brazing '''Brazed'''] on.

=====[https://en.wikipedia.org/wiki/Drill_bit#Lip_and_spur_drill_bits Dowel Bits]=====
[[File:DowelBits.png|200px|right]]

Ordinary HSS Twist Drills can be used to drill wood but, because of its fibrous nature, this can result in the grain tearing and leaving a rough edge to the hole. '''Dowel Bits''' ''(aka Brad Point or Spur Point drills)'' are not ground to the usual Point Angle but are sharpened to have a small point at the tip of the bit and '''''spurs''''' on either side which first cut across the grain to ensure clean, straight holes. They can often be made of [https://en.wikipedia.org/wiki/Carbon_steel#Higher-carbon_steels '''Carbon Steel'''] instead of '''HSS''' and, if so, are not suitable for use on harder metals but similar drills, with a 90° Point Angle, can be used for drlling plastics and some softer metals such as '''Copper'''.

=====Masonry Bits=====
[[File:MasonryBits.png|200px|right]]