Bolt or bolt tip name and standard?

[JohnDB]

These bolts have a plain end that's good for locating them in holes. They aren't tri-lobe or other thread forming.

I can't find anything about this style on the 'net, do you know if it has a particular name, and is there a standard or rule of thumb for the dimensions of the unthreaded portion?

I can guess a rule of thumb from the dimensions, but I'm curious to know if there's something more formal.

Thinking of modifying some M12 through-bolts to this arrangement.

Thanks in advance.

 

[ken erickson]

I believe “pilot point” bolt or “dog point” is the most common descriptor for this style bolt. My impression is that “dog point” bolts and screws are more commonly used as “set” screws rather than a “pilot “ point bolt used for aid in assembly or alignment.

I do not know if there is a standardized formal engineering specifications for diameter and length of point in relation to bolt size and application. I do know that the diameter must be turned down to at least minor diameter of thread size and pitch for the point to aid in alignment during assembly.

Common uses range from oil pan plug bolts to automotive body and fender bolts.

 

[Rcflyer330]

As far as I know there is no rule of thumb for dimensions unless there is a specific hole it must fit into. for the dimensions in the picture, that bolt was turned to or slightly smaller then the minor diameter of the thread. The minor diameter for a m8 is around 6.6mm. A m12 minor diameter would be around 10.1 mm. If that pin is just to locate the bolt for easy threading then the pin length can be whatever you want. Just make sure you leave enough threads for the bolt to do its job without stripping.

If I was to make this with an m12 bolt I think I would start with turning the diameter down to between 9.5 to 9.8 mm, a length of 6 to 7.5mm then adjust from there. Another way, if you don't want to measure, is just eyeball it. Turn the threads to solid metal and let the length be what looks good to you. Buy a few extra bolts and experiment to see what works.

 

[JohnDB]

Thanks @ken erickson and @Rcflyer330.

For the life of me I couldn't find the name even after scrolling through pages of bolt images, and now you've solved it.

I was interested in whether there was a standard but I guess there's no need, it's just got to fit the hole and do the job. I'll ask a friend with a lathe to turn some existing bolts down for me. The example has a nice ~0.5mm radius rolled on the leading edge, will do something similar with a file on the lathe.

 

[TheOldHokie]

Thanks @ken erickson and @Rcflyer330.

For the life of me I couldn't find the name even after scrolling through pages of bolt images, and now you've solved it.

I was interested in whether there was a standard but I guess there's no need, it's just got to fit the hole and do the job. I'll ask a friend with a lathe to turn some existing bolts down for me. The example has a nice ~0.5mm radius rolled on the0 leading edge, will do something similar with a file on the lathe.

Of course there are standards promulgated by the usual players

I have not looked but Machinerys Handbook probably has a section with some of the data

BS 4168 (United Kingdom)
ASME B18.3.6M (United States)
DIN 915 (Germany)
ISO 4028 (Most of the world)

But that does not gaurantee that (application specific ??) fastener is conformant.

Dan

 

[Gus1957]

I believe “pilot point” bolt or “dog point” is the most common descriptor for this style bolt. My impression is that “dog point” bolts and screws are more commonly used as “set” screws rather than a “pilot “ point bolt used for aid in assembly or alignment.

I do not know if there is a standardized formal engineering specifications for diameter and length of point in relation to bolt size and application. I do know that the diameter must be turned down to at least minor diameter of thread size and pitch for the point to aid in alignment during assembly.

Common uses range from oil pan plug bolts to automotive body and fender bolts.

Pardon Our Interruption...

Listed as pilot point on eBay - Nissan part

 

[Gus1957]

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Listed as Dog Point in catalog . Learned something new. TY

 

[JohnDB]

OK, this is great! @ken erickson seems to have summed it up: dog point for locking into holes or recessess in shafts etc, like the standards @TheOldHokie refers, and pilot point usually reserved for alignment/assembly @Gus1957 's Nissan example. On the science of self alignment is MAThreads https://www.bulten.com/en/products/bolts-and-screws/self-aligning-screws-bolts/ (and they use both terms pilot and dog so there we go Very helpful, thanks team!

 

[dvcochran]

As others have said, there are a few different names so go to Fastenal, McMaster-Carr or similar and you can 'build' the bolt(s) you need. 'Partial thread bolt' is also a common name.
Fastenal Bolt Selection

 

[chim]

After a few failures of a Fastenal branch near our shop to match some bolts we needed, I nicknamed them "Fastensome".

 

[PoTreeBoy]

Of course there are standards promulgated by the usual players

I have not looked but Machinerys Handbook probably has a section with some of the data

BS 4168 (United Kingdom)
ASME B18.3.6M (United States)
DIN 915 (Germany)
ISO 4028 (Most of the world)

But that does not guarantee that (application specific ??) fastener is conformant.

Dan

Here's what BS 4168 in the 23rd edition (1988) says. Sorry, this was before B18.3.6M, I believe. In any case, I think OP's is non-standard; he thinks it's for alignment to facilitate thread engagement, not to lock two parts together. Also, the flange head implies the bolt head is the stop; with set screws, the bottom end is the stop.

 

[Dustball]

Thinking of modifying some M12 through-bolts to this arrangement.

Thanks in advance.

What's the application? Would M12 drain plugs work?

Oil Drain Plug - M12-1.75 Pilot Point - Wholesale / Bulk

Oil Drain Plug - M12-1.75 - 15MM Head - Interchanges: 090-034, 11520, DP7825, D7825, 78-25

www.buyautosupply.com

 

[JohnDB]

@PoTreeBoy yes, correct the flange head is the stop, its not a setscrew/grubscrew, so that explains why there's probably no standard for such an assembly type of bolt end.

@Dustball thanks, a drain plug will be too short. Its to bolt a 10mm thick plate to another using 4 x bolts in a relatively inaccessible location = needs to be easy to assemble by feel.

Its the ADHD/OCPD in me that wondered about a name and standard for these things so naturally I turned to OTT for help and received it. I'll grab a couple of bolts and turn the ends down.