What happened here ? M 10

[Hal.]

Any thoughts for the community ?

[John Cuthber]

I think it's screwed.

[Xittenn]

The bolt was too long and bottomed out and the cap was still free to move. The amount of thread there, above the break, was probably in an untapped over sized bore. Somebody applied too much torque on it when it bottomed and it twisted off like an old school bottle cap? Is there a particular answer you are looking for?

 

Somebody may have forgotten to use the appropriate washer .....

[Hal.]

I don't think screwed is defined in engineering terms .

 

There is no known ' solution ' because I don't know what happened to it . Compression ? , Tension ? , Torque ? , Karate Chop ? ...............

[Xittenn]

Actually it is pretty obvious based on the formation of the break ... :/

[Hal.]

Xittenn , some terms may be used in one country and not in another . Can I bother you for a meaning of ' Bottom out ' and ' Bottomed ' ?

[Xittenn]

Xittenn , some terms may be used in one country and not in another . Can I bother you for a meaning of ' Bottom out ' and ' Bottomed ' ?

 

I'm sorry I think that a) that is pretty self explanatory from the description and b) I have never met an English speaking person, regardless of nationality, who would be in an appropriately related profession, who hasn't used or understood this statement in any of the probable contexts(of which there are several) ... I am refraining from answering this question.

Edited April 18, 2011 by Xittenn

[Hal.]

Xittenn , there is a first time for everything . Hi , I don't know what these terms mean and if you don't want to explain , don't . The expression you use may be slang . I thought that it might be American , if you say it is in common use I'll find it's meaning somewhere quite easily .

[Xittenn]

[Hal.]

[lemur]

I think it looks like it broke while being loosened, probably because whatever it was threaded into had shifted in a way that prevented it from loosening and whoever was trying to loosen it kept applying torque in the hope that it would break/give (by "break" here, I mean the moment when the bolt goes from being stationary to turning).

 

btw, I think another way to say "bottomed out" could be that it couldn't move further into the hole. Sorry, xitten, if this undermines your insistence on the term "bottomed out" being comprehensible to all English-speakers, which I actually agree with if they would use a tiny bit of imagination. As for your explanation, I tried thinking of ways to tell if it broke while tightening or loosening but I could come up with reasons both ways. Loosening was my initial impression, though.

Edited April 19, 2011 by lemur

[Xittenn]

I think the strongest evidence to suggest that this didn't happen on the way out lemur, is that there exists an intact broken off portion. If it had gotten stuck on the way out and sufficiently so as to break the Allen Screw the most likely thing to have followed would have been the drilling and possible subsequent re-taping of the hole. Also if tools had been used to take the piece out without a head it would have left a mark that would have been worth mentioning; assuming it could have been taken out whole. You can also, again, tell by the formation of the break and where the slope and the rise meet the 'stock' or the 'break' respectively.

 

And undermine away .... I was just not going to bother with such a trite detail ....

Edited April 19, 2011 by Xittenn

[SMF]

Bottoming out is a clear concept. What of the obvious hole in the bottom piece, could this have been drilled for an (not so) Easy Out extraction? If broken on tightening it would require a non-threaded portion as Xitten says. It could be broken on extraction with a completely threaded hole, but I have never had this happen with a solid Allan head bolt. Usually the Allan wrench twists off and there is no sign of a Vise Grip (or other) assist to the Allan wrench. If the hole through the bottom piece is preexisting then this could explain the breakage because the screw would be weak at the top of this section. I am stumped. SM

[Xittenn]

I disagree about the hole being obvious, I think it looks more like the dimple of an extremely worn out set screw .... but I could be wrong and if it is a hole well maybe it was extraction .... I don't think I am though :/

 

If it was a through drill I would expect to see some striations in the shiny bit and some burring ...

Edited April 19, 2011 by Xittenn

[Hal.]

Here is the original image and another of the image it came from .

 

 

 

 

Edited May 15, 2011 by Hal.

[Realitycheck]

The bolt was too long and bottomed out and the cap was still free to move. The amount of thread there, above the break, was probably in an untapped over sized bore. Somebody applied too much torque on it when it bottomed and it twisted off like an old school bottle cap? Is there a particular answer you are looking for?

 

Somebody may have forgotten to use the appropriate washer .....

I'm pretty sure that it bottomed out and was over-torqued. It was longer than it should have been, or it was missing a washer/spacer.

 

In other words, the bottom edge of the bolt hit the base of the bore hole/tap before the head could tightly secure the object with the hole in it. So the bolt was tightened dow all the way into its receptacle. Since it was too long to secure the object, it was tightened exceedingly, to try and take up the slack, but broke because there was no more room for the thread to fit. Does that make sense?

Edited May 15, 2011 by Realitycheck

[Hal.]

The image of the bolt on it's own is a crop from the other image of the 3rd bolt down and it has also been resized upwards .

[Realitycheck]

By the way, it is just a hollow bolt, very weak, not sure why, maybe even plastic. Been there, done that.

[Hal.]

I don't think the bolts are hollow and I do think they show metallic brittle fractures .

[Moontanman]

I am not an engineer but I worked with engineers for much of my career with DuPont and i have seen the very thing you are showing in the pics with bolts that "appear" to actually be the same bolts we used in high pressure very hot (300c) polymer pipes. The bolt always comes out like that, you can tell by the lack of damage to the threads that the bolt was not twisted off, that would have broken it above the threads. It is entirely possible that the bolt may have failed due to inherent flaws that made the bolt break when heated (we used them at 350c) and torqued (100fp). We never knew the bolt was broken until we removed the bolt but we were far more likely to see this in manifolds that had been allowed to cool to room temperature after being bolted with hot bolts when the pipes were also very hot. .

 

Oh yeah, one of the studies showed the number of broken bolts went up when we bolted cold bolts into hot manifolds as well, it's been a long time, sorry if it's not helpful.

Edited May 16, 2011 by Moontanman

[Hal.]

Can I say , these bolts do not exist to me as a physical problem that requires a solution . They are from the web and when I saw them a good year ago , I thought they were very interesting . Everything is helpful , everyone can take their own views .