12 point head bolt 1

[rQuestionEngineering]

Why do bolts have different type of head design ? and what are the advantages of each ? How application is evaluated ?

1. 12 point head
2. Hex head
3. Cap screw
4. Stud and nut separate

 

[SnTMan]

Partial list:

1) Used when small head diameter, light weight is wanted (ex aviation). 12 pt to provide adequate strength for torqueing. Disadvantage: No crescent wrenches
2) Most common, low cost, works for very many applications
3) [Assumed as socket head] various head styles available, ex socket, flat, button, etc. [In some uses any headed machine fastener is considered a cap screw]
4) Used in services where dis-assembly is frequent, ease of dis-assembly is important, (ex pipe flanges, heavy machine parts). Studs may remain in place, nuts only removed, etc.

Lots more...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

It's called 'market forces deciding'.
Most of the outcomes are bad, e.g., VHS over Betamax.
But none worse than the Phillips screw head.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[SnTMan]

But none worse than the Phillips screw head.

Ever try to power drive a slot head?

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[kingnero]

yes, 30 years ago... I doubt it's still commonly available in Europe so that problem solves itself

another reason: so-called "security" or to make something moron-proof. I'm mostly speaking of safety-torx (with the little pin in the middle of the hole), or splined heads as used in automotive applications, or OEM design screws in electronic/electric equipment...

 

[3DDave]

The hex is a compromise. Comparing the options:

1 face - that would be a smooth round, obviously difficult to easily wrench, though pipe wrenches do work
2 faces - not sure what that shape would be, maybe like a thumbscrew - the advantage is that for thin head design the contact angle is nearly 90 degree. The disadvantage is the head is thin and easily broken off.
3 faces - requires a tool that fits all three at the same time to produce leverage; requires 120 degrees of turn to get to next position, 60 degrees if wrench is offset
4 faces - tools are simple to make, just a constant width slot; requires only 90 degrees to get to next position, 45 degrees if wrench is offset; face pairs can have some offset such that a slight rhombus would also work; they have excellent contact angle mating with tool (45 degrees)
5 faces - tools are more difficult to make, but not entirely uncommon, requires contacting three faces to turn, only 72/36 degrees to get to next position
6 faces - tools are simple to make and compatible with 4 face fasteners; requires only 60/30 degrees to get to next position. Note that this also means up to 12 engagements per full turn. The contact angle is 30 degrees
7 faces - tools are more difficult same as 3 and 5.
8 faces - tools that fit 6 and 4 can fit this, but the contact angle is small increasing the chances of rounding the corners from the fastener or damaging the tools. The contact angle is about 22 degrees

skip to

12 POINT - these are, essentialy, 2X 6 faced fasteners. The contact angle is back to 30 degrees and is now distributed over up to 12 faces. This requires additional precision to mate correctly. They are typically used where the torque requirements are high but the volume to fit a 6 face fastener is not available.

 

[CWB1]

Be very careful when selecting or even discussing drive systems, there are many that appear very similar but have very different costs and require different tools. I wish I had a nickel for every DIY mechanic that mistook an external torx for a 12-point hex.

From an engineering standpoint, usually you choose a drive system based on a combination of cost, torque capacity/limitations, and desire to prevent disassembly.

 

[3DDave]

The worst are the Torq-set recesses. Designed to not be compatible with Phillips recess, they attract a ton of attack vectors that leave everyone the worse for wear. They are also, in conversation, confused with Torx, and are in no way related except being found in screws. Seeing the abuse, they were supplemented with Tri-Wing recesses. At least no one grabs a Phillips driver.

 

[BrianPetersen]

JIS versus Phillips is the one that irks me. Japanese motorcycles are filled with screws having JIS heads, and JIS screwdrivers are not readily found here. A Phillips screwdriver will sort-of work, but if the screw is tight, it will "cam out" and strip the head of the screw.

I like Torx and "e" (inverse of Torx). They seem the most resistant to stripping.

Triple-square (type XZN) are resistant to stripping, too, until someone attempts to jam a regular or 12-point (not the same!) socket onto them.

 

[Tmoose]

And then there is Reed & Prince or Frearson. Not quite Philips, and vice versa.

 

[EdStainless]

All of my JIS screwdrivers say Shimano on them, for my bike work. It took me years to figure that out.

We used a lot of 12 point (Ferry cap screw) in places where we needed to fully load the bolts and there wasn't room for a std hex head.
In fact we had them custom made in Monel K-500.
These were the ones that a std 12 point socket would fit.

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P.E. Metallurgy, Plymouth Tube