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Home / Screws / Grade 12.9 High-Strength Socket Set Screw Cup Point Machine Screw Set Screw Kit M3 M4 M5 M6 M8

Attributes

Brand -
Category Standard Parts, Components & Industrial Consumables / Screws
Origin -
Material Grade Alloy Steel Grade 12.9
Head Style Socket Cup Point
Drive Type Hex Socket (Allen)
Included Sizes M3, M4, M5, M6, M8
Surface Finish Black Oxide Coated
Thread Standard ISO Metric Coarse
Hardness Rating HRC 39-44
Tensile Strength 1220 MPa Minimum
Package Contents Assorted Kit with Storage Box
Application Heavy Duty Machinery & Automotive

6 reviews

A

Anonymous

Mar 25, 2026

Rating: 4/5

Very hard, be careful not to overtighten

Grade 12.9 is no joke; these are extremely hard. Make sure you use a calibrated torque wrench because it is easy to snap the head off if you apply too much force. Otherwise, great product.

A

Anonymous

Mar 23, 2026

Rating: 5/5

Reliable industrial grade fasteners

I order these regularly for our production line. Consistency is key, and this batch matched our specifications exactly. No defects found in the hundreds of screws we inspected.

A

Anonymous

Mar 18, 2026

Rating: 4/5

Good value for money

Solid set of screws for the price. The storage case is a bit flimsy, but the screws themselves are top-notch. Would recommend for any serious DIYer or mechanic.

A

Anonymous

Mar 11, 2026

Rating: 5/5

Excellent quality for heavy machinery

These screws are incredibly strong. I used the M6 and M8 sizes to secure components on a lathe, and they held up perfectly under high vibration. The hex sockets are precise and didn't strip.

A

Anonymous

Mar 02, 2026

Rating: 5/5

Perfect fit for automotive projects

Used the M5 screws for a custom intake manifold setup. The cup point digs in well to prevent slipping. The threads were clean and rolled smoothly into the tapped holes.

A

Anonymous

Mar 01, 2026

Rating: 5/5

Great assortment kit

Having all these common metric sizes in one box is a lifesaver for my workshop. The black oxide finish looks professional and seems to offer decent corrosion resistance for indoor use.

5 FAQ

Q: What is the return policy if the sizes don't match my needs?

A: We offer a 30-day return policy for unused items in their original packaging. Please contact our customer service team to initiate a return request.

Q: Does this kit include a thread locking compound?

A: No, this kit includes only the socket set screws and the storage box. Thread locking compound is sold separately.

Q: Are these screws suitable for outdoor applications?

A: While the black oxide finish offers some protection, Grade 12.9 steel is susceptible to rust in wet environments. For outdoor use, we recommend applying a thread-locking fluid with corrosion inhibitors or using stainless steel alternatives if strength requirements allow.

Q: What size Allen key do I need for the M6 screw?

A: For standard ISO metric socket set screws, an M6 screw typically requires a 5mm hex key. However, please verify with a caliper as tolerances can vary slightly by manufacturer.

Q: Can these be used in aluminum threads?

A: Yes, but caution is advised. Because Grade 12.9 is much harder than aluminum, there is a risk of galling or stripping the aluminum threads if over-torqued. Use proper torque settings and consider using a thread insert for high-load applications.

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