OT Metal question source/data

This should help  *LINK*


https://www.engineering.com/calculators/beams.htm

Re: This should help

Gary Smyth

Dick, Thank you! The plug ins work for almost in every value I want to check for this project. Now part of my "favorites".

If playing with tubing or hollows and different values (another idea) I sometimes get a NaN calculation. I believe that that is "Not a Number" but what does that mean? Is it a go or no go? Lastly what is the source? Seems like something I should have -- maybe already do have.

Re: This should help

Ellis Walentine

Cool site, Dick. I don't see a way, though, to differentiate between a point load and a uniformly distributed load. I'm guessing that these calculations assume a point load centered on the length of the beam. If I were a more savvy engineer, I'd probably understand it better...

Re: OT Metal question source/data

Bill Tindall, E.Tn.

this weight does not seem much to challenge even a modest bracket. think book shelf with 100 pounds of books. I think you are over thinking the requirement. Do you doubt the bracket you illustrate would successfully hold 100 pounds?

diagram?

John K Jordan

>>>loads

It did look simplistic. My first thought was it was interesting but it needs a diagram to define the support and load positions. My second thought was it didn't seem applicable to a horizontal beam with a web support like the scroll in the second photo or with the cross-section changes in as in the third photo.

I see it has titanium in the materials list and I have some 10' lengths tubing - my third thought was it would be fun to try applying a weight in various configuration and see how close the numbers came to the actual deflection.

The "wood" material entry seems simplistic too, but perhaps a starting point.

Ok, I'm out of thoughts now. But I still bookmarked the page.

JKJ

Re: OT Metal question source/data

Barry Irby

I agree with Bill. 27 lbs doesn't seem like much. Use any bracket that looks sturdy with an angle brace in it. I think the weak link in this might be the top screw that holds it to the wall. The force is trying to extract the screw as much as shear it off. A good screw would be better than a nail.

Re: This should help

Dick Coers

I just found that yesterday with a Google search. I never ceased to be amazed at how easy engineering calculations can be now. When I started as a draftsman for Caterpillar Research Division in Oct 1972, they had a room filled with engineers, that all they did was calculate all day long. Finite element analysis, beam loads, etc. Hard to visualize row after row of guys using slide rules today! Guys that lived on cigarettes and coffee. Guys that had to empty their ash trays at noon. Certainly a different time.

Re: This should help

MartinMJ

I do not think I know an engineer that smokes. We called those rooms full of engineers bullpens in aerospace and they have long transformed into cubicle farms. But the latest trend is to go back to a bullpen like open area with no assigned space. Try to find your supervisor in that sea of bodies when he has a different location each day!

Way back in 86 it took a small static model of one SRB cable cover 6 hrs to run on the latest 'hot' DEC computer. Then the IBM workstation arrived. I submitted the model and 3 minutes later - 'bing', signalling the job completed. I thought there was a data error. No, it was done. As was the era of those massive mainframes.

NaN

John in NM

Usually it just means that the calculator returned an invalid value.

Agree....

John in NM

27 lbs is pretty minimal for a steel bracket. The loading will be very different than shelves though, so I would err on the stout side. 3/16" X 1" strap with a scroll welded in would be perfectly sturdy. Probably 1/8" strap would be ok too, depending on the design.

Barry's right about the top screw too - I would use a long heavy screw into a very solid piece of wood. Otherwise I could see the swinging weight causing the screws to loosen long before the bracket bends.

Re: NaN

John K Jordan

Perhaps when a calculation sees a "divide by zero".

Re: OT Metal question source/data

Gary Smyth

I plugged in several values on the lengths, and added weight this time up to 40 pounds. No braces on these plug ins. The deflection was four zeros after the decimal point before the first number. I'm confident that deflection will not be a problem even if it hangs for years or someone pulls at it. The wood backing was a concern for me too so I intend instead to use anchor bolts into a brick wall and epoxy them in. It should last my lifetime.

Re: NaN

John in NM

That one is the most common I think. Trig also gives you lots of undefined conditions.

Re: NaN

Larry Barrett

I tried the calculator and for one of the dimensions I entered 1/8 and got the NaN when I hit 'Calculate'. I then changed the 1/8 to .125 and got a result.

Re: NaN

John K Jordan

Ha, an input error. I never even considered someone might write the parser to accept fractions. However, it would have been easy (and nice) for the programmer to echo the error to give the user a clue to what he did wrong. Lazy programmer.

JKJ

Re: NaN

John in NM

Unfortunately, that kind of laziness in programming is all too common!

Re: OT Metal question source/data

Lowell Johnson

I bit more information is needed to calculate the sizes needed for the brace. This is a fairly simple problem, a type first presented in college physics. Step one: draw a free body diagram. That is a "stick" diagram from the side, with all relevant dimensions given and best drawn to scale. How far from the wall do you want the bell? Compare this to brackets used for hanging flower baskets. (My brackets bent when I switched from 16" to 18" baskets.)

There will be deflection, the only question is how much. With the bell hanging 12" from the wall, 1/16 would be a reasonable target, without an angle brace.

The topmost mounting fastener is a separate problem but also important. It will be loaded in a combination of shear and tension. It may be easier to find tables for this. The inputs are the fasteners type, length, diameter, and the material behind it.

That online calculator is not explained well enough to use. It is apparently for a horizontal simple span beam, with a concentrated load at the center. It needs a free body diagram to explain. My understanding is that your problem is a cantilever beam.