8-40 Bolts | McMaster-Carr

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	System of Measurement System of Measurement

Inch

	Thread Size Thread Size	Show

8-40

	Thread Size Thread Size	Hide

	Length Length

	Drive Style Drive Style


Hex	Slotted

	Drive Size Drive Size

3/32"

	Threading Threading

	Fully Threaded

	Head Type Head Type


Rounded	Thumb

	Material Material

Stainless Steel

	Thread Spacing Thread Spacing

Extra Fine

	Head Height Head Height

0.087"

1/2"

	Head Diameter Head Diameter

1/4"

0.312"

	Thread Direction Thread Direction

	Right Hand

	Thread Type Thread Type

UNS

	Rounded Head Profile Rounded Head Profile

Standard

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	RoHS (Restriction of Hazardous Substances) RoHS (Restriction of Hazardous Substances)

RoHS Compliant

	Tensile Strength Tensile Strength

70,000 psi

80,000 psi

	Thread Fit Thread Fit

Class 2A

Class 3A

	Hardness Hardness

Rockwell B55

Rockwell B83

	Rounded Head Style Rounded Head Style

	Button

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

DFARS Specialty Metals
Compliant

	Round-Head Thumb Screw Profile Round-Head Thumb Screw Profile

	Narrow

	Thumb Screw Head Shape Thumb Screw Head Shape

	Round

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9 Products

About Thumb Screw and Binding Post Materials

About Rounded Head Screws

18-8 Stainless Steel Button Head Hex Drive Screws

18-8 stainless steel button head screws have good chemical resistance and may be mildly magnetic. Length is measured from under the head.

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

18-8 Stainless Steel

Stainless Steel

8-40
Lg.	Threading	Head Dia.	Head Ht.	Drive Size	Tensile Strength, psi	Pkg. Qty.		Pkg.
1/4"	Fully Threaded	0.312"	0.087"	3/32"	70,000	1	000000000	00000
3/8"	Fully Threaded	0.312"	0.087"	3/32"	70,000	1	000000000	0000
1/2"	Fully Threaded	0.312"	0.087"	3/32"	70,000	1	000000000	0000

Narrow Knurled-Head Thumb Screws

Use these slim thumb screws in tight spaces. Made from 18-8 stainless steel, they're chemical resistant and may be mildly magnetic. The head is knurled for slip-resistant controlled adjustment. Length is measured from under the head.

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

		Head
Lg.	Threading	Dia.	Ht.	Tensile Strength, psi	Hardness		Each
18-8 Stainless Steel
8-40
1/2"	Fully Threaded	1/4"	1/2"	80,000	Rockwell B83	000000000	00000
3/4"	Fully Threaded	1/4"	1/2"	80,000	Rockwell B83	000000000	0000
1"	Fully Threaded	1/4"	1/2"	80,000	Rockwell B83	000000000	00000

Slotted Narrow Knurled-Head Thumb Screws

These thumb screws are slim to fit in tight spaces. Made from 18-8 stainless steel, they're chemical resistant and may be mildly magnetic. The head is knurled for slip-resistant controlled adjustment. Length is measured from under the head.

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

		Head
Lg.	Threading	Dia.	Ht.	Tensile Strength, psi	Hardness		Each
18-8 Stainless Steel
8-40
1/2"	Fully Threaded	1/4"	1/2"	80,000	Rockwell B83	000000000	000000
3/4"	Fully Threaded	1/4"	1/2"	80,000	Rockwell B83	000000000	00000
1"	Fully Threaded	1/4"	1/2"	80,000	Rockwell B83	000000000	00000