How do I calculate the force on a threaded rod? 3

[GogiBOB]

Hi,
I am trying to calculate how much force can my threaded rod withstand.
My 5/16-18" 304 S/S threaded rod is inserted into the metal plate of 0.25" thickness so there are 4.5 threads inserted in the plate.

There's upward force from the center of the plate which is 0.95" away from the rod.

Can anyone give me a heads up?
Thanks!

 

[zekeman]

"'s not mind reading, Zekeman, it's taking a look at the problem and using common sense. As pointed out by a few in this discussion for example, there is not enough information to properly answer the problem. Working through the problem in a step-by-step fashion, I made an assumption based on the missing information. This uncertainty led me to speculate that it was possible to at least get a theoretical answer.

This computation is only a preliminary study. Obviously a more detailed analysis is required.

Regards,"


It's mind reading 101...

 

[dhengr]

I lauded Cockroach for his effort and presentation, on an OP which was poorly defined and presented. The poor, incomplete question reflects badly on the OP’er. and his engineering experience and abilities, no one else. Cockroach made a few assumptions, consistent with what little info. was given, out of dozens of possible interpretations, and offered one possible tack on the problem. He also showed a set of hand calcs. for these types of problems, which would be a good example for many of these people to be able to emulate. Since, many of them couldn’t engineer their way out of a paper bag which was open at both ends, without $20,000 worth of computer stuff at their disposal. And, then, they still wouldn’t know if they had a real answer to their problem.

I agree with Zekeman on the issue that we see way too many poorly posed questions here a E-Tips. I can’t help but wonder if some of these are from high school science or tech students, certainly not college students or graduate engineers, one hopes. And, it scares the hell out of me that some of these might be real tech people designing products or structures which will be foisted on the public and maybe hurt someone, for lack of any real engineering input into their design. And, I don’t know who to blame/damn for this state-of-affairs; the company which expects non-engineers to engineer their products, on the cheap; or the engineer (young or otherwise) who has oversold his abilities to the point that he can’t even define his design problem, and is trying to get us to help him dig out of the hole he made for himself.

I just tend to ignore questions which don’t have enough info. for an intelligent discussion. If the guy couldn’t waste the time to post an intelligent question with sufficient info., why should I waste my time trying to decipher what he wants or needs? He probably wouldn’t understand what was said anyway, or worse yet might misuse it in a dangerous way. By the way, I am all for helping other engineers with a problem they may not have seen before, but I would like them to show a little native ability in the engineering area they claim to be practicing in. And like Zekeman, I wonder, if they can’t even pose an intelligent engineering question, should I help them pretend to be engineers.

 

[zekeman]

Dhengr,

Spot on. I couldn't agree with you more.

What scares me that in addressing these poorly defined problems and giving answers sometimes with caveats, the socalled "engineer" may then take the info and "design" something completely out of whack that may be unsafe, putting somebody at risk of life and limb.

Perhaps a policy change at the administrator level should give us, the responders, better guidelines in giving answers to these oblique inquiries.

 

[GogiBOB]

I realize my question was very poorly described and not enough information was given to solve the problem.I was just hoping to get some heads up. ... Next time I;ll make sure I provide every piece of information when I ask a question.

Yes I am a fresh graduate and have no real experience.
I went though two textbooks on statics from university and none of them mentioned thread engagement.

Again, my apologies for being ignorant.

and thank you again cockroach for your help.

regards,

 

[dhengr]

GogiBOB:
Nobody else said ignorant, so don’t you either; lazy maybe, inexperienced probably... But, you should start thinking like a real working engineer, where every aspect of a problem is not given to you on a golden platter. You actually have to dig for some of the needed design info. And, you have to step through the problem in a logical fashion, just as Cockroach did for you.

The take-away here should be to provide a sketch; read through your word-picture (description), word-for-word, and it better be detailed enough so any of us can only draw one picture as we read it. If there can possibly be two or three interpretations, then you’ve got us guessing (wasting our time) and there’s a good chance that you might get the wrong answer. We can’t see, from here, what you are imagining or CADing, you gotta show us. Even if you are a new grad. engr., and we all were once upon a time, think through your problem, what info. is needed to come to a solution, these guys will need that info. to give you good advice. There are a bunch of really sharp people here willing and able to help. At the same time, they are giving you their time and experience, so don’t waste it just because you are lazy in your OP or further posts to the thread. Then follow your thread, and don’t leave people who have helped hanging, finally when you have your answer close out the thread, with a Thank You, as you have done.

If you aspire to do this kind of design and to be a good Mech.E., you should have a few good Strength of Materials, Engineering Mechanics and Machine Design text books as your best friends. Maybe a good Mech. Engr’s. Handbook, Marks’ comes to mind, for general info. Also, get a copy of Machinery’s Handbook, pub. by Industrial Press, Inc. for a wealth of mechanical info. Cockroach has undoubtedly done that set of calcs. more than a few times in his life, and I’ll bet a dollar to a doughnut that he used a few ref. books while he did the above calcs. I certainly don’t remember all those values and formulas without looking them up, and I don’t have the time to develop them each time, our advantage is we already have those ref. pages marked, and know where to look.

 

[GogiBOB]

Lessons I learned from this single thread is more then I learned from my engineering ethics class. Thank you for your words!

 

[rb1957]

for better, or for worse ?

 

[GogiBOB]

rb1957/ for better of course

I recently had some time to work on this project and tried to prove the model by adapting the options Cockroach suggested. While I understand adding a washer/nut would help the rod to resist bending stress I am not too sure which equations to mathematically prove. Can anyone give me a little more explanation?

Also, I don't have much mechanical background and having hard time looking for references.
Is there any good mechanical engineering reference books other then Machinery's handbook?(I just ordered one!)