Precision Surfaces | McMaster-Carr

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53 Products

Surface Plates


Rectangular Plate	Rectangular Plate with Two Ledges

With flatness tolerances thinner than a strand of hair, these plates give you the flattest possible surface for accurate measurements. They’re typically used as a reference plane to inspect finished products and calibrate precision measuring tools, such as height gauges and dial indicators. Unlike metal plates, these granite plates won’t rust or interfere with nearby electronics. They also won’t warp when temperatures fluctuate. To maintain their flatness and finish, rotate plates regularly and apply granite cleaner (not included) to remove particles without leaving a residue.

Also Available: Other plate sizes. Please order 2245A999 and specify grade, length, width, thickness, and with or without ledges.

Laboratory-Grade AA Plate—Best for precision inspections and quality-control work in calibration labs. These plates have the tightest flatness tolerance for the highest level of accuracy.

Inspection-Grade A Plate—Your go-to for general inspections and quality-control work. These plates are slightly less precise than grade AA plates with double the flatness tolerance.

Toolroom-Grade B Plate—Suitable for checking routine measurements throughout a shop. These plates are the least precise with four times the flatness tolerance of grade AA plates.

Rectangular Plate with Two Ledges—Choose these plates if you need to mount fixtures and instruments with a clamp.

Black—Harder and denser than red plates to handle heavier loads, such as large bearings and other machined parts.

Red—Resist wear better than black plates to last up to five times longer. With a higher percentage of quartz, you can slide parts across these plates without worrying about nicks and scratches.

Surface Plate Covers—Prevent dust and debris from accumulating on plates when you’re not using them.

	Plates													Surface Plate Covers
								Rectangular Plate			Rectangular Plate with Two Ledges
	Flatness Tolerance	Lg.	Wd.	Ht.	Color	Specs. Met	Certificate Type	Wt., lb.		Each	Wt., lb.		Each		Each
Laboratory-Grade AA Plate





				Black Granite

				0.00005"	6"	4"	2"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	7	2245A101	0000000	—	———	0	———	0
				0.00005"	12"	8"	2"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	28	2245A81	000000	—	———	0	22455A101	0000000
				0.00005"	18"	12"	4"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	93	2245A39	000000	83	2245A72	0000000	22455A64	00000
				0.000075"	24"	18"	4"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	185	2245A41	000000	175	2245A53	000000	22455A65	000000
				0.0001"	36"	24"	6"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	601	2245A42	00000000	—	———	0	22455A66	000000
				0.0002"	48"	36"	6"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	1,203	2245A82	00000000	—	———	0	22455A67	000000




						Granite

						0.00005"	18"	12"	4"	Red	ASME B89.3.7, Fed. Spec. GGG-P-463	Accuracy Certificate Traceable to NIST	84	2245A105	00000000	—	———	0	22455A64	00000
						0.000075"	24"	18"	4"	Red	ASME B89.3.7, Fed. Spec. GGG-P-463	Accuracy Certificate Traceable to NIST	168	2245A106	00000000	—	———	0	22455A65	000000


						Inspection-Grade A Plate





										Black Granite

										0.0001"	6"	4"	2"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	7	2245A102	000000	—	———	0	———	0
										0.0001"	12"	8"	2"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	28	2245A83	000000	—	———	0	22455A101	000000
										0.0001"	18"	12"	4"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	93	2245A43	000000	83	2245A46	000000	22455A64	00000
										0.00015"	24"	18"	4"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	185	2245A44	000000	175	2245A47	000000	22455A65	000000
										0.0002"	36"	24"	6"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	555	2245A45	00000000	530	2245A48	00000000	22455A66	000000
										0.0004"	48"	36"	6"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	1,110	2245A56	00000000	1,063	2245A49	00000000	22455A67	000000




												Granite

												0.0001"	12"	8"	2"	Red	ASME B89.3.7, Fed. Spec. GGG-P-463	Accuracy Certificate Traceable to NIST	20	2245A104	000000	—	———	0	22455A101	000000


												Toolroom-Grade B Plate





																Black Granite

																0.0002"	6"	4"	2"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	7	2245A103	000000	—	———	0	———	0
																0.0002"	12"	8"	2"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	21	2245A23	000000	—	———	0	22455A101	000000
																0.0002"	18"	12"	3"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	70	2245A24	000000	66	2245A62	000000	22455A64	00000
																0.0003"	24"	18"	3"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	139	2245A21	000000	130	2245A63	000000	22455A65	000000
																0.0004"	36"	24"	4"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	370	2245A26	000000	357	2245A64	000000	22455A66	000000
																0.0008"	48"	36"	6"	Black	ASME B89.3.7, Fed. Spec. GGG-P-463, ISO 10012	Accuracy Certificate Traceable to NIST	1,203	2245A38	00000000	—	———	0	22455A67	000000

Surface Plate Stands

Mobile

Stationary

Attach to plates at three support points to keep them from sagging and warping, as specified in Fed. Spec. GGG-P-463-c. The welded steel construction offers greater strength, durability, and stability than economical alternatives such as block and wedge systems.

Mobile—Conduct measuring and inspecting tasks anywhere in your facility. With steel plate casters and hard, durable wheels, these stands support the same capacities as their stationary counterparts. Turn the adjustable screws on top of the stand to level the plate on uneven floors.

Stationary—Create a permanent setup for routine measurements and inspections. Twist the mounts at the bottom of each leg to level the plate, even on uneven floors.

	For Plate						For Rectangular Plates		For Rectangular Plates with Two Ledges
	Lg.	Wd.	Ht.	Load Cap., lb.	Ht.	Material		Each		Each
Mobile



		18"	12"	3", 4"	400	36"	Painted Steel	2196A711	0000000	2196A712	0000000
		24"	18"	3", 4"	500	36"	Painted Steel	2196A721	000000	2196A722	000000
		36"	24"	4", 6"	1,200	36"	Painted Steel	2196A731	00000000	2196A732	00000000
		48"	36"	6"	2,400	36"	Painted Steel	2196A741	00000000	2196A742	00000000


		Stationary



				18"	12"	3", 4"	400	36"	Painted Steel	2196A811	000000	2196A812	000000
				24"	18"	3", 4"	500	36"	Painted Steel	2196A821	000000	2196A822	000000
				36"	24"	4", 6"	1,200	36"	Painted Steel	2196A831	000000	2196A832	000000
				48"	36"	6"	2,400	36"	Painted Steel	2196A841	000000	2196A842	000000

Calibration Squares

Tri-Squares

Squares

Check the tool path of your CNC machine with the highest degree of precision. These calibration squares can lay flat to check that the X- and Y-axes of your tool path are at 90°. Or sit them up vertically to confirm the Z-axis is perpendicular. Made of Laboratory Grade AA granite, these squares have the tightest flatness tolerance available for granite. They also come with a calibration certificate traceable to NIST that states they've passed a test for accuracy. Moisture, coolant, and chips won't affect the granite, so they remain accurate even when used inside a milling machine. You can also use them to check the squareness and parallelism of finished workpieces.

They have drilled holes to reduce their weight and make them easy to position.

Tri-Squares—Tri-square plates have a face and two edges for checking 3-axis machines.

Squares—Square plates have two additional edges for checking both 3-axis and 5-axis machines.

						Tolerance per 6"
	No. of Finished Edges	No. of Finished Faces	Lg.	Wd.	Ht.	Flatness	Squareness	Parallel	Color	Material	Surface Plate Grade	Certificate Type		Each
Tri-Squares



		2	1	12"	9"	3"	0.00005"	0.00005"	—	Black	Granite	Laboratory Grade AA	Calibration Certificate Traceable to NIST	6177N11	000000000


		Squares



				4	1	12"	12"	3"	0.00005"	0.00005"	0.00005"	Black	Granite	Laboratory Grade AA	Calibration Certificate Traceable to NIST	6177N12	00000000