Starrett Squares | McMaster-Carr

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Square Head with Built-In Level

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84 Products

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


	Inch

Square head checks 90° angles.

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		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	0000000	0000000

Replacement Square Head Lockbolts

		Each
Replacement Lockbolt for Square and Center Heads	0000000	000000

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 and Scriber


	Inch/Metric

Inch

Square head checks 90° angles.

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	—	Silver	Black	Etched	2 13/32"	0000000	0000000	—	———	0


		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	2 13/32"	0000000	000000	2 13/32"	0000000	0000000
		6"	1/32" (4/32"), 1/64" (8/64")	1/50" (1/10"), 1/100" (1/10")	-0.002" to 0.004"	3/4"	5/64"	Steel	Satin	Chrome, Silver	Black	Etched	2 13/32"	0000000	000000	2 13/32"	0000000	000000
		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	000000	—	———	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	4 1/2"	0000000	000000	3 5/8"	0000000	000000
		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	4 1/2"	0000000	000000	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	Satin	Chrome, Silver	Black	Etched	4 1/2"	0000000	000000	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	Satin	Chrome, Silver	Black	Etched	4 1/2"	0000000	000000	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	Satin	Chrome, Silver	Black	Etched	4 1/2"	0000000	000000	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	Satin	Chrome, Silver	Black	Etched	4 1/2"	0000000	000000	3 5/8"	0000000	000000

Replacements for Squares

		Each
Replacement Case for Combination Squares with 12" Long Blade	0000000	000000
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, 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	000000
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

		Each
Replacement Case for Combination Squares with 12" Long Blade	0000000	000000
Replacement Lockbolt for Square, Center, and Protractor Heads	0000000	0000

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
				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	Satin	Chrome, Silver	Black	Etched	—	———	0	3 5/8"	0000000	000000

Replacements for Squares

		Each
Replacement Case for Combination Squares with 12" Long Blade	0000000	000000
Replacement Lockbolt for Square, Center, and Protractor Heads	0000000	0000

Starrett High-Accuracy Combination Square Heads

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

Square Heads

Square heads check 90° angles.

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.	Features		Each		Each
4"	—	0000000	000000	0000000	000000
6"	Built-In Level	0000000	00000	0000000	000000
12" to 48"	Built-In Level	0000000	00000	0000000	000000

Replacement Square Head Lockbolts

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

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

Protractor Heads

Protractor heads measure angles.

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

			Protractor		Cast Iron
For Blade Lg.	Reversible	Features	Angle Measured Range	Graduations (Numeric Increments)		Each
12" to 48"	No	Built-In Level	0° to 180°	1° (10°)	0000000	0000000
12" to 48"	Yes	Built-In Level	0° to 180°	1° (10°)	0000000	000000

Replacement Square Head Lockbolts

For Head Style	For Blade Lg.		Each
Center, Square, Protractor	12" to 36"/300 mm to 600 mm	0000000	00000

Starrett High-Accuracy Squares

These squares meet Fed. Spec. GGG-S-656-E, which establishes uniform standards for square accuracy to ensure reliable, repeatable angles.

	Squares								Measuring Square Cases
			Blade
	Angle Measured	Blade Lg.	Wd.	Thk.	Min. Lg. Accuracy	Color		Each		Each
Inch







				Steel

				90°	1 1/2" × 1 1/2"	1/2" × 17/32"	3/64" × 1/4"	0.0001"	Silver	0000000	0000000	0000000	000000


				90°	3" × 2 3/8"	47/64" × 7/8"	1/16" × 13/32"	0.0001"	Silver	0000000	000000	0000000	00000
				90°	4 1/2" × 3 1/2"	1 1/8" × 15/16"	23/32" × 1/2"	0.0001"	Silver	0000000	000000	0000000	00000
				90°	6" × 4 5/16"	1 5/16" × 1 1/16"	5/64" × 1/2"	0.0001"	Silver	0000000	000000	0000000	00000
				90°	12" × 7"	2" × 1 31/64"	5/64" × 3/4"	0.0002"	Silver	0000000	00000000	0000000	000000

Starrett High-Accuracy Combination Square Blades


Inch	Inch/Metric

Use these blades with Starrett High-Accuracy Combination Square Heads. They meet Fed. Spec. GGG-R-791, which establishes uniform standards for accuracy, graduations, and size. Blades are labeled with numeric increments that are less than 1" for quick reading. All have a corrosion-resistant satin chrome-plated finish that reduces glare and wear-resistant etched markings.

								Graduation
	Lg.	Front Graduations (Numeric Graduations)	Back Graduations (Numeric Graduations)	Lg. Accuracy	Wd.	Thk.	Color	Color	Type		Each
Inch







				Satin Chrome-Plated Steel

				4"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.002" to 0.004"	5/8"	1/16"	Silver	Black	Etched	0000000	000000


				6"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.002" to 0.004"	3/4"	5/64"	Silver	Black	Etched	0000000	00000
				6"	1/32" (4/32"), 1/64" (8/64")	1/50" (1/10"), 1/100" (1/10")	-0.002" to 0.004"	3/4"	5/64"	Silver	Black	Etched	0000000	00000
				12"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.005"	1"	3/32"	Silver	Black	Etched	0000000	00000
				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"	Silver	Black	Etched	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"	Silver	Black	Etched	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"	Silver	Black	Etched	0000000	000000
				36"	1/32" (4/32"), 1/64" (8/64")	1/8" (1"), 1/16" (1")	-0.0035" to 0.007"	1"	3/32"	Silver	Black	Etched	0000000	000000


				Inch/Metric







								Satin Chrome-Plated Steel

								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"	Silver	Black	Etched	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"	Silver	Black	Etched	0000000	000000

Starrett Protractors with Adjustable Arm


Half-Round Head	Rectangular Head

Also known as bevel protractors, set bevels and measure angles with the adjustable arm. All have graduations from 0° to 180° in both directions. They have a corrosion-resistant satin-chrome finish that reduces glare and wear-resistant etched markings.

					Head				Graduation
	Degree Angle Measured Range	Degree Graduations (Angle Increments)	No. of Arms	Arm Length	Shape	Ht.	Wd.	Color	Color	Type	Mfr. Model No.		Each
Satin Chrome-Plated Steel



		0° to 180°	1° (10°)	1	6"	Half Round	2"	3 1/4"	Silver	Black	Etched	C19	0000000	0000000


		0° to 180°	1° (10°)	1	6"	Rectangle	2"	3 3/8"	Silver	Black	Etched	C183	0000000	000000

Starrett Protractors with Graduated Arm

Measure angles and dimensions with one tool. Protractor has graduations from 0° to 180° in both directions. Also known as a bevel protractor, it has an adjustable arm. The arm is narrow to fit into holes for use as a depth gauge. It has a corrosion-resistant satin-chrome finish that reduces glare and wear-resistant etched markings.

				Arm				Head				Graduation
	Degree Angle Measured Range	Degree Graduations (Angle Increments)	No. of Arms	Lg.	Wd.	Front Graduation Marks (Numeric Increments)	Back Graduation Marks (Numeric Increments)	Shape	Ht.	Wd.	Color	Color	Type	Mfr. Model No.		Each
Satin Chrome-Plated Steel







				Inch

				0° to 180°	1° (10°)	1	6"	3/16"	1" (1"), 1/64" (1")	1" (1"), 1/32" (1")	Rectangle	2"	3 3/8"	Silver	Black	Etched	C493B	00000000	0000000