Centering Heads | McMaster-Carr

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Square Head with Built-In Level

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66 Products

Center-Locating Punches for Curved Surfaces

Locate and mark the centerline on rods, tubes, and pipes, lay out keyways, and establish angles for connections.

Manual—Manual locators are for use with a hammer. Gently strike the rod to mark the center.

Spring Loaded—Spring-loaded locators mark the center with the pull of a trigger.

Adjustable Dial Protractor—Locators with an adjustable dial protractor aid in establishing marks for angled connections.

Angle Measured Range	Graduations	Angle Numeric Increments	For Min. Pipe OD	Material	Punch Material	Includes	Features		Each



Manual	0° to 90°	2.5°	10°	1/2"	Aluminum	Steel	Adjustable Dial Protractor	Bubble Level	000000	0000000


Spring Loaded	0° to 90°	2.5°	10°	1"	Aluminum	Steel	Adjustable Dial Protractor	Bubble Level	000000	000000

Replacement Levels

		Each
Replacement Dial/Level Assembly	0000000	000000

High-Accuracy Combination Square Heads

Attach to High-Accuracy Combination Square Blades with the included lockbolts.

Center Heads

Center heads identify the center on pipes, rods, and shafts.

Zinc—Zinc heads are lightweight and corrosion resistant.

Cast Iron—Cast iron heads are durable, so they resist dents and scratches. However, they corrode more easily than zinc heads.

Hardened Cast Iron—Hardened cast iron heads are more durable and last longer than cast iron heads.

	Combination Square Center Heads			Replacement Square Head Lockbolts
	For Blade Lg.		Each		Each
Zinc



		12" to 24"	00000000	00000	000000000	00000


		Cast Iron



				12" to 24"	00000000	00000	00000000	0000


				Hardened Cast Iron



						12" to 24"	00000000	00000	00000000	0000

Combination Squares

Replace your try square, miter square, depth gauge, marking gauge, 90° level, ruler, and scriber with one tool. Blades labeled with numeric increments that are less than 1" are quick-reading.

Blades with Square Head with Built-In Level, Center Head, Reversible Protractor Head with Built-In Level, and Scriber


	Inch/Metric

Square head checks 90° angles.

Protractor head measures angles.

Center head identifies the center on pipes, rods, and shafts.

Etched—Etched graduation marks are wear resistant.

				Blade				Graduation		Aluminum Square Head
	Blade Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Wd.	Thk.	Material	Color	Color	Type	Head Lg.		Each
Inch/Metric



		12"/300 mm	1 mm (10 mm), 1/32" (4/32")	1 mm (10 mm), 1/16" (1")	1"	3/32"	Steel	Silver	Black	Etched	4 1/4"	000000	000000

High-Accuracy Combination Squares

Use these squares in place of your try square, miter square, depth gauge, height gauge, center-point finder, and level. Blades are labeled with numeric increments that are less than 1" for quick reading.

Blades with Square Head with Built-In Level, Center Head, and Scriber


	Inch

Square head checks 90° angles.

Center head identifies the center on pipes, rods, and shafts.

Hardened Cast Iron Square Head—Hardened cast iron square heads are more durable and last longer than cast iron square heads.

Satin Blade—Satin blade appearance is corrosion resistant and reduces glare.

Etched—Etched graduation marks are wear resistant.

					Blade					Graduation			Cast Iron Square Head		Hardened Cast Iron Square Head
	Blade Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Lg. Accuracy	Wd.	Thk.	Material	Appearance	Color	Color	Type	Head Lg.		Each		Each
Inch



		12"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0025" to 0.0025"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	4 1/2"	00000000	0000000	00000000	0000000

Replacement Square Head Lockbolts

		Each
Replacement Lockbolt	00000000	00000

Blades with Square Head with Built-In Level, Center Head, Reversible Protractor Head, and Scriber


	Inch

Square head checks 90° angles.

Protractor head measures angles.

Center head identifies the center on pipes, rods, and shafts.

Hardened Cast Iron Square Head—Hardened cast iron square heads are more durable and last longer than cast iron square heads.

Satin Blade—Satin blade appearance is corrosion resistant and reduces glare.

Etched—Etched graduation marks are wear resistant.

					Blade					Graduation			Cast Iron Square Head		Hardened Cast Iron Square Head
	Blade Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Lg. Accuracy	Wd.	Thk.	Material	Appearance	Color	Color	Type	Head Lg.		Each		Each
Inch



		12"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0025" to 0.0025"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	4 1/2"	00000000	0000000	00000000	0000000

Replacement Square Head Lockbolts

		Each
Replacement Lockbolt	00000000	00000

Scratch-Resistant High-Accuracy Combination Squares

A titanium coating protects the blade against scratches and wear. Use these squares to replace your try square, miter square, depth gauge, height gauge, center-point finder, and level. Blades are labeled with numeric increments that are less than 1" for quick reading.

Blades with Square Head with Built-In Level, Center Head, Protractor Head, and Scriber


	Inch

Square head checks 90° angles.

Protractor head measures angles.

Center head identifies the center on pipes, rods, and shafts.

Etched—Etched graduation marks are wear resistant.

					Blade				Graduation		Cast Iron Square Head
	Blade Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Lg. Accuracy	Wd.	Thk.	Material	Color	Color	Type	Head Lg.		Each
Inch



		12"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.002" to 0.002"	1"	3/32"	Titanium-Coated Steel	Gold	Black	Etched	4 1/2"	00000000	0000000

Starrett High-Accuracy Combination Square Heads

Attach to Starrett High-Accuracy Combination Square Blades with the included lockbolts.

Center Heads

Center heads identify the center on pipes, rods, and shafts.

Cast Iron—Cast iron heads are durable, so they resist dents and scratches. However, they corrode more easily than zinc heads.

Hardened Steel—Hardened steel heads are more durable and last longer than cast iron heads.

	Cast Iron		Hardened Steel
For Blade Lg.		Each		Each
4"	0000000	000000	0000000	000000
6"	0000000	00000	0000000	000000
12" to 48"	0000000	00000	0000000	000000

Replacement Square Head Lockbolts

For Head Style	For Blade Lg.	Each
Center, Square	4"	000000
Center, Square	6"	00000
Center	6"	00000
Center, Square, Protractor	12" to 36"/300 mm to 600 mm	0000

Starrett High-Accuracy Combination Squares

Replace your try square, miter square, depth gauge, height gauge, center-point finder, and level. The blade on these squares meets Fed. Spec. GGG-R-791H, which establishes uniform standards for accuracy, graduations, and size. Blades are labeled with numeric increments that are less than 1" for quick reading.

Blades with Square Head and Center Head


	Inch

Square head checks 90° angles.

Center head identifies the center on pipes, rods, and shafts.

Satin Blade—Satin blade appearance is corrosion resistant and reduces glare.

Etched—Etched graduation marks are wear resistant.

					Blade					Graduation		Cast Iron Square Head
	Blade Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Lg. Accuracy	Wd.	Thk.	Material	Appearance	Color	Color	Type	Head Lg.		Each
Inch



		4"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.002" to 0.004"	5/8"	1/16"	Steel	Satin	Chrome, Silver	Black	Etched	2 1/4"	0000000	0000000

Replacement Square Head Lockbolts

		Each
Replacement Lockbolt for Square and Center Heads	0000000	000000

Blades with Square Head with Built-In Level, Center Head, and Scriber


	Inch

Square head checks 90° angles.

Center head identifies the center on pipes, rods, and shafts.

Hardened Steel Square Head—Hardened-steel square heads are more durable and last longer than cast iron square heads.

Satin Blade—Satin blade appearance is corrosion resistant and reduces glare.

Etched—Etched graduation marks are wear resistant.

					Blade					Graduation		Cast Iron Square Head			Hardened Steel Square Head
	Blade Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Lg. Accuracy	Wd.	Thk.	Material	Appearance	Color	Color	Type	Head Lg.		Each	Head Lg.		Each
Inch



		6"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.002" to 0.004"	3/4"	5/64"	Steel	Satin	Chrome, Silver	Black	Etched	—	———	0	2 13/32"	0000000	0000000


		12"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.005"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	4 1/2"	0000000	0000000	3 5/8"	0000000	000000

Replacements for Squares

		Each
Replacement Case for Combination Squares with 12" Long Blade	0000000	0000000
Replacement Lockbolt for Center Heads	0000000	00000
Replacement Lockbolt for Square and Center Heads	0000000	00000
Replacement Lockbolt for Square, Center, and Protractor Heads	0000000	0000

Blades with Square Head with Built-In Level, Center Head, Protractor Head, and Scriber


	Inch

Square head checks 90° angles.

Protractor head measures angles.

Center head identifies the center on pipes, rods, and shafts.

Etched—Etched graduation marks are wear resistant.

					Blade				Graduation		Cast Iron Square Head
	Blade Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Lg. Accuracy	Wd.	Thk.	Material	Color	Color	Type	Head Lg.		Each
Inch



		12"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.005"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	0000000


		18"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.006"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
		24"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.007"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000

Replacements for Squares

Blades with Square Head with Built-In Level, Center Head, Reversible Protractor Head, and Scriber


	Inch/Metric

Inch

Square head checks 90° angles.

Protractor head measures angles.

Center head identifies the center on pipes, rods, and shafts.

Hardened Steel Square Head—Hardened-steel square heads are more durable and last longer than cast iron square heads.

Satin Blade—Satin blade appearance is corrosion resistant and reduces glare.

Etched—Etched graduation marks are wear resistant.

					Blade					Graduation		Cast Iron Square Head			Hardened Steel Square Head
	Blade Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Lg. Accuracy	Wd.	Thk.	Material	Appearance	Color	Color	Type	Head Lg.		Each	Head Lg.		Each
Inch



		12"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.005"	1"	3/32"	Steel	—	Silver	Black	Etched	4 1/2"	0000000	0000000	—	———	0


		12"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.005"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	—	———	0	3 5/8"	0000000	0000000
		12"	1/32" (4/32"), 1/64" (8/64")	1/50" (1/10"), 1/100" (1/10")	-0.0035" to 0.005"	1"	3/32"	Steel	—	Silver	Black	Etched	4 1/2"	0000000	000000	—	———	0
		12"	1/32" (4/32"), 1/64" (8/64")	1/50" (1/10"), 1/100" (1/10")	-0.0035" to 0.005"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	—	———	0	3 5/8"	0000000	000000
		18"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.006"	1"	3/32"	Steel	—	Silver	Black	Etched	4 1/2"	0000000	000000	—	———	0
		18"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.006"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	—	———	0	3 5/8"	0000000	000000
		18"	1/32" (4/32"), 1/64" (8/64")	1/50" (1/10"), 1/100" (1/10")	-0.0035" to 0.006"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	—	———	0	3 5/8"	0000000	000000
		24"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.007"	1"	3/32"	Steel	—	Silver	Black	Etched	4 1/2"	0000000	000000	—	———	0
		24"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.007"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	—	———	0	3 5/8"	0000000	000000
		24"	1/32" (4/32"), 1/64" (8/64")	1/50" (1/10"), 1/100" (1/10")	-0.0035" to 0.007"	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	—	———	0	3 5/8"	0000000	000000


		Inch/Metric



				11 3/4"/300 mm	0.5 mm (10 mm), 1/32" (4/32")	1 mm (10 mm), 1/64" (8/64")	-0.0035" to 0.005"/ -0.09 mm to 0.15 mm	1"	3/32"	Steel	—	Silver	Black	Etched	4 1/2"	0000000	000000	—	———	0


				11 3/4"/300 mm	0.5 mm (10 mm), 1/32" (4/32")	1 mm (10 mm), 1/64" (8/64")	-0.0035" to 0.005"/ -0.09 mm to 0.15 mm	1"	3/32"	Steel	Satin	Chrome, Silver	Black	Etched	—	———	0	3 5/8"	0000000	000000
				23 1/2"/600 mm	0.5 mm (10 mm), 1/32" (4/32")	1 mm (10 mm), 1/64" (8/64")	-0.0035" to 0.007"/ -0.11 mm to 0.25 mm	1"	3/32"	Steel	—	Silver	Black	Etched	4 1/2"	0000000	000000	—	———	0

Replacements for Squares

Magnetic Pipe Flange Aligners with Level

Ensure an even seal around your flange—these tools align and level flanges in a single step. The strong magnets make sure your bolt holes are perfectly inline horizontally and that your flange isn’t tilted. If your flange is made of stainless steel or another nonmagnetic material, secure these aligners using the included threaded cones.

	For Max. Flange Hole Ctr.-to-Ctr. Distance	Level Lg.	Aligner Connection Method	Includes	Cone Material	Magnet Material	Container Type		Each
Aluminum Body



	1/2" to 2"	9 1/2"	10 1/2"	Magnetic	Threaded Cones	Steel	Neodymium	Carrying Case	0000000	0000000

Pipe Flange Aligners with Protractor

Line up two pipe flanges and determine pipe angle with the included nut-and-bolt pins, level, and protractor. Flange holes align as you tighten the pins.

	Angle Measured Range	Graduations (Angle Increments)	For Distance Between Bolt Holes		Each
Aluminum



	3/16" to 1 3/4"	0° to 90°	2.5° (2°)	2" to 5 1/2"	0000000	0000000

Pipe Flange Aligner Pins with Horizontal Level

Ensure horizontal alignment of pipe flanges with a level rod that runs between two alignment pins. One pin in each pair has a level for vertical alignment. Insert these nut-and-bolt pins into adjacent flange holes and tighten to align flanges before connecting two pipes.

	Aligner Connection Method	Rod Lg.		Each
Steel



	1/2" to 1 7/16"	Screw Together	10"	00000000	0000000


	1/2" to 1 15/16"	Screw Together	18"	00000000	000000

Pipe Flange Alignment Kits

Hand-Crank Alignment

Ratchet Alignment

Hydraulic Alignment

Align flanges on heavy pipes when alignment pins don't fit through the flange holes. Often used for pipefitting, welding, and maintenance, these kits make it possible to correct angular and offset misalignment on a range of pipe sizes.

Choose an alignment mechanism based on how much force you need to move the pipe. If you're not sure, measure the flange hole diameter—it correlates to the pressure class and size of your pipe. Larger pipes typically require more force.

Hand-Crank Alignment—Hand-crank aligners are best for routine maintenance and quick repairs. As you turn the hand crank, it moves the pipe.

Ratchet Alignment—Ratchet aligners produce four times as much force as hand crank aligners. Position the tool's arm through a flange hole on the pipe you plan to move, and place the lead screw on the edge of the stationary pipe's flange. Wrap the strap around the pipe you plan to move. As you rotate the lead screw with a wrench, the misaligned pipe moves into position.

Hydraulic Alignment—Hydraulic aligners are best for severe misalignment—they generate over twice as much force as ratcheting aligners. Position the tool's arm through the flange hole on the pipe you plan to move, and place the lead screw on the edge of the stationary pipe's flange. Wrap the strap around the pipe you plan to move. As you press down on the hand pump connected to the lead screw, the pipe moves.

Alignment Mechanism	Wt. Cap., lb.	For Min. Flange Hole Dia.	Includes	Container Type	Each
Hand Crank	2,400	5/8"	Strap	—	000000000
Ratchet	9,900	1"	Socket, Strap, Wrench	Plastic Carrying Case	00000000
Hydraulic	22,200	1 3/8"	Hand Pump with Gauge, Hydraulic Cylinder, Hydraulic Hose, Strap	Plastic Carrying Case	00000000

Stepped Pipe Flange Aligner Pins

Each step on these aligner pins matches common bolt holes on pipe flanges, so they're more precise than conical aligner pins and don’t require nuts. Press the pair of pins into mated flanges to make sure the flanges are aligned. Once two sets of holes are aligned, you'll know the rest of the holes are as well. Made of durable chrome-plated steel, they'll hold their shape over time and resist rust.

	Lg.		Pair
Chrome-Plated Steel



	3/8" to 3/4"	3 5/8"	0000000	000000


	3/4" to 1 1/4"	5 1/2"	0000000	00000
	3/4" to 1 3/8"	8"	0000000	00000

Pipe Flange Aligner Pins

Insert a pair of these nut-and-bolt pins into adjacent flange holes and tighten to align flanges before connecting two pipes. One pin in each pair has a level for vertical alignment. Use a separate level to align the flange horizontally. Also known as two-hole pins.

4 1/2" Lg. Extension—Pins with a 4 ½” length extension let you increase the length of your pins to align thicker flanges.

Two Couplings—Use the included couplings to connect the extension to your pins.

	For Flange
	Hole Dia.	Thk.	Aligner Connection Method	Includes		Pair
Steel



		5/16" to 15/16"	1"	Screw Together	—	0000000	000000


		1/2" to 1 7/16"	2 1/2"	Screw Together	—	0000000	00000
		1/2" to 1 15/16"	4"	Screw Together	—	0000000	000000
		5/8" to 3"	9"	Screw Together	4 1/2" Lg. Extension, Two Couplings	0000000	000000

Replacements for Pipe Flange Aligners

For Flange Hole Dia.	Material	Lg.		Each
5/8" to 3"	Steel	1"	0000000	00000

For Flange Hole Dia.	Material	Lg.		Each
5/8" to 3"	Steel	2 7/8"	0000000	00000
5/8" to 3"	Steel	4 1/2"	0000000	0000

Magnetic Pipe Flange Aligner Pins

Swiftly and accurately align pipe flange bolt holes without the hassle of threads. These pins have strong magnets that snap together. Insert them into adjacent bolt holes to help make sure flanges are parallel before connecting pipes. Also known as two-hole pins.

For 2 3/4" Flange Thickness—Pins for 2 _3/4" thick flanges can be used with pipe flange aligner extensions (sold separately) to lengthen their reach for flanges up to 3 _1/2″ thick.

	Pipe Flange Aligners						Pipe Flange Aligner Extensions
	For Flange
	Hole Dia.	Thk.	Aligner Connection Method	Magnet Material		Pair	Lg.		Each
Steel



		5/16" to 7/8"	7/8"	Magnetic	Neodymium	0000000	000000	—	———	0


		1/2" to 1 7/16"	1 3/8"	Magnetic	Neodymium	0000000	000000	—	———	0
		3/4" to 1 15/16"	2 3/4"	Magnetic	Neodymium	0000000	000000	1 3/4"	0000000	000000