Iron Squares | McMaster-Carr

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	Square Head Material Square Head Material

Cast Iron

Hardened Cast Iron

	Material Material

High-Speed Steel

Iron

	System of Measurement System of Measurement

Inch

Metric

	Blade Length Blade Length

	Blade Width Blade Width

5/8"

3/4"

	Blade Thickness Blade Thickness

1/16"

5/64"

3/32"

	Component Component

Blade

Square Head with Built-in
Level

Square Head

Center Head

Reversible Protractor Head
with Built-in Level

Reversible Protractor Head

Nonreversible Protractor
Head with Built-in Level

	Graduation Marks Graduation Marks

	Numeric Increments Numeric Increments

1/10"

4/32"

1 cm

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

	Blade Material Blade Material

Steel

	Manufacturer Model Number Manufacturer Model Number

	Blade Color Blade Color

	Silver
	Gold

	Head Length Head Length

2 1/4"

2 13/32"

4 1/2"

	For Maximum Blade Length For Maximum Blade Length

24"

48"

	Graduation Location Graduation Location

Front

Back

	Graduation Mark Style Graduation Mark Style

Etched

	Manufacturer Manufacturer

Starrett

	Graduation Color Graduation Color

	Black

	Angle Measured Angle Measured

90°

	Center Head Material Center Head Material

Cast Iron

Hardened Cast Iron

	For Use On For Use On

	Housing Material Housing Material

Iron

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69 Products

About Carbon Steel, Alloy Steel, Spring Steel, and Cast Iron

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. All have wear-resistant etched markings.

Square head checks 90° angles. Center head identifies the center on pipes, rods, and shafts. Protractor head measures angles.

Satin-chrome blade finish is corrosion resistant and reduces glare.

Blade with Square Head

Inch

				Blade				Graduation		Cast Iron Head
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
4"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	5/8"	1/16"	Satin-Chrome Steel	Silver	Black	Etched	2 1/4"	0000000	000000

Replacement Lockbolt for Square and Center Heads

0000000

Each

000000

Blade with Square Head and Center Head

Inch

				Blade				Graduation		Cast Iron Heads
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
4"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	5/8"	1/16"	Satin-Chrome Steel	Silver	Black	Etched	2 1/4"	0000000	0000000

Replacement Lockbolt for Square and Center Heads

0000000

Each

000000

Blade with Square Head with Built-in Level and Scriber

Inch

Inch/Metric

				Blade				Graduation		Cast Iron Head
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
6"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	3/4"	5/64"	Steel	Silver	Black	Etched	2 13/32"	0000000	000000
6"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	3/4"	5/64"	Satin-Chrome Steel	Silver	Black	Etched	2 13/32"	0000000	000000
6"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.002" to +0.004"	3/4"	5/64"	Satin-Chrome Steel	Silver	Black	Etched	2 13/32"	0000000	000000
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	00000
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
12"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
Inch/Metric
11 3/4"/300mm	1/2 mm (10 mm), 32nds (4/32")	Millimeters (10 mm), 64ths (8/64")	-0.0035" to +0.005"/ -0.09 mm to +0.15 mm	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
23 1/2"/600mm	1/2 mm (10 mm), 32nds (4/32")	Millimeters (10 mm), 64ths (8/64")	-0.0035" to +0.007"/ -0.11 mm to +0.25 mm	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000

Replacement Lockbolt for Square, Center, and Protractor Heads	0000000	Each	00000
Replacement Lockbolt for Square and Center Heads	0000000	Each	00000

Blade with Square Head with Built-in Level, Center Head, and Scriber

Inch

				Blade				Graduation		Cast Iron Heads
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
6"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.004"	3/4"	5/64"	Satin-Chrome Steel	Silver	Black	Etched	2 13/32"	0000000	0000000
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
12"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.005"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	0000000	000000

Replacement Lockbolt for Square, Center, and Protractor Heads	0000000	Each	00000
Replacement Lockbolt for Center Heads	0000000	Each	00000
Replacement Lockbolt for Square and Center Heads	0000000	Each	00000

Blade with Square Head with Built-in Level, Center Head, Protractor Head, and Scriber

Inch

				Blade				Graduation			Cast Iron Heads
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	0000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000

Replacement Lockbolt for Square, Center, and Protractor Heads

0000000

Each

00000

Blade with Square Head with Built-in Level, Center Head, Reversible Protractor Head, and Scriber


	Inch
	Inch/Metric

				Blade				Graduation		Cast Iron Heads
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.005"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	0000000
12"	32nds (4/32"), 64ths (8/64")	50ths (1/10"), 100ths (1/10")	-0.0035" to +0.005"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
18"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.006"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
24"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0035" to +0.007"	1"	3/32"	Steel	Silver	Black	Etched	4 1/2"	0000000	000000
Inch/Metric
11 3/4"/300mm	1/2 mm (10 mm), 32nds (4/32")	Millimeters (10 mm), 64ths (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
23 1/2"/600mm	1/2 mm (10 mm), 32nds (4/32")	Millimeters (10 mm), 64ths (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

Replacement Lockbolt for Square, Center, and Protractor Heads

0000000

Each

00000

Starrett High-Accuracy Combination Square Heads

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

Square head checks 90° angles. Center head identifies the center on pipes, rods, and shafts. Protractor head measures angles.

Square Head

Center Head

Protractor Head

		Protractor
Component	For Blade Lgs.	Angle Measuring Range	Graduation Marks (Numeric Increments)		Each
Cast Iron
Square Head	4"	__	__	0000000	000000
Square Head with Built-in Level	6"	__	__	0000000	00000
Square Head with Built-in Level	12"-48"	__	__	0000000	00000
Center Head	4"	__	__	0000000	00000
Center Head	6"	__	__	0000000	00000
Center Head	12"-48"	__	__	0000000	00000
Nonreversible Protractor Head with Built-in Level	12"-48"	0°-180°	1° (10°)	0000000	000000
Reversible Protractor Head with Built-in Level	12"-48"	0°-180°	1° (10°)	0000000	000000

Replacement Lockbolts

For Head Style	For Blade Lgs.		Each
Center	6"	0000000	000000
Square, Center	4"	0000000	00000
Square, Center	6"	0000000	00000
Square, Center, Protractor	12"-36"/300 mm-600 mm	0000000	0000

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. All have a corrosion-resistant satin-chrome finish that reduces glare and wear-resistant etched markings.

Square head checks 90° angles. Center head identifies the center on pipes, rods, and shafts. Protractor head measures angles.

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

Blade with Square Head with Built-in Level and Scriber

Inch

				Blade				Graduation
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Cast Iron Head
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	000000
Hardened Cast Iron Head
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	000000

Replacement Lockbolt

00000000

Each

00000

Blade with Square Head with Built-in Level, Center Head, and Scriber

Inch

				Blade				Graduation
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Cast Iron Heads
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	0000000
Hardened Cast Iron Heads
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	000000

Replacement Lockbolt

00000000

Each

00000

Blade with Square Head with Built-in Level, Center Head, Reversible Protractor Head, and Scriber

Inch

				Blade				Graduation
Blade Lg.	Front Grad. Marks (Increments)	Back Grad. Marks (Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Cast Iron Heads
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	0000000
Hardened Cast Iron Heads
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.0025" to +0.0025"	1"	3/32"	Satin-Chrome Steel	Silver	Black	Etched	4 1/2"	00000000	000000

Replacement Lockbolt

00000000

Each

00000

High-Accuracy Combination Square Heads

Square Head

Center Head

Protractor Head

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

Square head checks 90° angles. Center head identifies the center on pipes, rods, and shafts. Protractor head measures angles.

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

		Protractor
Component	For Blade Lgs.	Angle Measuring Range	Graduation Marks (Numeric Increments)		Each
Cast Iron
Square Head with Built-in Level	12"-24"	__	__	00000000	000000
Center Head	12"-24"	__	__	00000000	00000
Reversible Protractor Head	12"-24"	0°-180°	1° (10°)	00000000	00000
Hardened Cast Iron
Square Head with Built-in Level	12"-24"	__	__	00000000	00000
Center Head	12"-24"	__	__	00000000	00000

Replacement Lockbolt

00000000

Each

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. All have wear-resistant etched markings.

Square head checks 90° angles. Center head identifies the center on pipes, rods, and shafts. Protractor head measures angles.

Blade with Square Head with Built-in Level and Scriber

Inch

				Blade				Graduation			Cast Iron Head
Blade Lg.	Front Graduation Marks (Numeric Increments)	Back Graduation Marks (Numeric Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.002"	1"	3/32"	Titanium-Coated Steel	Gold	Black	Etched	4 1/2"	00000000	0000000

Blade with Square Head with Built-in Level, Center Head, Protractor Head, and Scriber

Inch

				Blade				Graduation			Cast Iron Heads
Blade Lg.	Front Graduation Marks (Numeric Increments)	Back Graduation Marks (Numeric Increments)	Accuracy	Wd.	Thick.	Material	Color	Color	Mark Style	Head Lg.		Each
Inch
12"	32nds (4/32"), 64ths (8/64")	8ths (1"), 16ths (1")	-0.002" to +0.002"	1"	3/32"	Titanium-Coated Steel	Gold	Black	Etched	4 1/2"	00000000	0000000

Easy-to-Machine Gray Cast Iron Sheets and Bars

Yield Strength: Not Rated
Hardness: Rockwell C20 (Hard)
Heat Treatable: Yes
Max. Hardness After Heat Treatment: Rockwell C50
Specifications Met: ASTM A247

Gray cast iron machines faster with less wear on cutting tools than most types of steel. It also absorbs vibration, so finished parts run quieter than those made of steel. It's often fabricated into gears, pulleys, and bushings.

For technical drawings and 3-D models, click on a part number.

Certificates with a traceable lot number are available for these products. Download certificates from ACTIVITY after your order ships.

2 5/8" Thick.
Wd.	Straightness Tolerance		1 ft. Lg.	2 ft. Lg.
2 5/8"	1/8" per 6 ft.	0000000	000000	0000000

Multi-Plane Levels

Two-Plane Cast Iron L

Adjust a surface into a level position on multiple planes.

Two-plane levels have two vials set at 90° angles to allow you to level in two directions simultaneously.

				No. of Vials			Housing
For Max. No. of Planes	Lg.	Wd.	Ht.	Horizontal	Vertical	Sensitivity	Material	Color	Vial Material		Each
L
2	2 3/4"	5/8"	2 3/4"	1	1	0.065 in./ft., 19 min./0.1"	Cast Iron	Black	Glass	0000000	000000

Multi-Plane Precision Levels with Calibration Certificate

Square

These levels come with a calibration certificate traceable to NIST that states they've passed a test for accuracy. They are precision-machined and check the accuracy of both horizontal and vertical surfaces simultaneously with two highly sensitive vials set at 90° angles.

V-groove provides stability on curved surfaces.

				No. of Vials			Housing				Mounting Holes
Lg.	Wd.	Ht.	For Max. No. of Planes	Horizontal	Vertical	Sensitivity	Material	Color	Vial Material	Mounting Fasteners Included	No. of	Dia.	Features		Each
T
3 5/32"	2 9/16"	0.667"	2	1	1	0.001 in./ft., 0 min./0.1"	Cast Iron	__	Glass	No	2	0.22"	__	000000000	0000000
Square
8"	1 9/16"	8"	2	1	1	0.0006 in./ft., 0 min./0.1"	Cast Iron	Green	Glass	__	__	__	V-Groove	00000000	00000000

Multi-Plane Precision Levels

Square

Check the accuracy of horizontal and vertical surfaces with these precision-machined levels. They have two highly sensitive vials set at 90° angles for checking two planes at the same time.

V-groove provides stability on curved surfaces.

				No. of Vials			Housing				Mounting Holes
Lg.	Wd.	Ht.	For Max. No. of Planes	Horizontal	Vertical	Sensitivity	Material	Color	Vial Material	Mounting Fasteners Included	No. of	Dia.	Features		Each
T
3 5/32"	2 9/16"	0.667"	2	1	1	0.001 in./ft., 0 min./0.1"	Cast Iron	__	Glass	No	2	0.22"	__	00000000	0000000
Square
8"	1 9/16"	8"	2	1	1	0.0006 in./ft., 0 min./0.1"	Cast Iron	Green	Glass	__	__	__	V-Groove	0000000	00000000

Grind-Your-Own Lathe Tool Blanks

Grind these hardened steel blanks to the size and shape you need.

PM T15 high-speed steel has excellent wear resistance and good heat resistance for use on all metal and plastic.

For technical drawings and 3-D models, click on a part number.

Square Shank

Shank					PM T15 High-Speed Steel
Wd.	Ht.	Overall Lg.	End Shape	Bevel Angle		Each
1/8"	1/8"	2 1/2"	Beveled	10°	0000000	000000
3/16"	3/16"	2 1/2"	Beveled	10°	0000000	00000
1/4"	1/4"	2 1/2"	Beveled	10°	0000000	00000
5/16"	5/16"	2 1/2"	Beveled	10°	0000000	00000
3/8"	3/8"	3"	Beveled	10°	0000000	00000
7/16"	7/16"	3 1/2"	Beveled	10°	0000000	00000
1/2"	1/2"	4"	Beveled	10°	0000000	00000
5/8"	5/8"	4 1/2"	Beveled	10°	0000000	00000
3/4"	3/4"	5"	Beveled	10°	0000000	00000
7/8"	7/8"	6"	Beveled	10°	0000000	000000
1"	1"	7"	Beveled	10°	0000000	000000