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The problem:

So basically I want to calculate the weight/pressure of TV that I want to mount on my wall so I can on my own later on find the right anchors, right fittings, and TBH I am interested in getting a formula on this one. So I will represent some of my sketches and thoughts and questions about the problem, but all in lay-man terms as I don't know else. You will see a lot of kinda non-physics related images, but those are for showing where the pressure point of both the mounts are, so you can get a better picture. I really tried finding an answer before questioning, but I couldn't with this particular use-case.

The trick is the following, I am looking for a mount that is capable of doing 90 degree swirl to one side, basically making the TV perpendicular to the wall. This means the mass of the TV will not have the same effect to the wall if it was parallel without an offset like usually. Another thing which makes me think about this problem is that my walls are constructed of vertically perforated brick, not a solid brick or consisting wooden wall studs, so I wanna make sure everything will be fine.

So by different swirling angles I mean from 0 to 90 degrees on a side, by different type of brackets, is the most interesting part for me that I want to figure it out which is having screws positioned on a horizontal vs vertical plate, and what would be the strongest.


The examples:

I am taking two mounting brackets, here are the images of a sketch with all the dimensions needed of both types.

The horizontally positioned mounting bracket that can swirl 90 degrees to a side:

enter image description here

The vertically positioned bracket that can also swirl 90 degrees to a side:

enter image description here

also I found another more detailed picture from the vertical one, it has screw hole distances and such, some holes are not correct, I will mention this later on, but in my physics question I think it doesn't really matter.

enter image description here


The questions (my concerns and current understandings):

As I already mentioned, I want to find the right anchors types and sizes which would be much more easy if I find the weight of the TV in few positions. I'll ask in two parts.

So first, without dictating the mounting bracket environments, how much weight does an rectangle which we would call a TV put to a line, which would we call a wall.

TV mass = 20 kg

TV width = 110 cm

  1. How much weight does the TV put on the wall at a parallel non offset setting?
  2. How much weight does the TV put on the wall at a parallel 60 cm offset to the wall setting. Note that the TV is mounted in the center of the bracket handler?
  3. How much weight does the TV put to the wall while being perpendicular e.g swirled at a 90 degree angle to the wall?
  4. How much weight does the TV put to the wall while being perpendicular and swirled at a 45 degree angle to the wall?

So basically I want to get an understanding of the formula that goes into this. Here is my visual representation of the first 3 questions.

enter image description here

The second part and that is how would each type of mounting bracket (or connection) affect the weight of the TV to the wall.

The first bracket has its screw holes placed on two horizontal lines, here is a picture:

enter image description here

Now I know that the pressure will be on the top screws so I can put more screws there compared to the bottom, and I thought this was a clear winner, which probably might be, but after realizing the following for the vertical bracket I am not sure for what difference.

So the second bracket is a vertical screw setup and as I mentioned, in one of the pictures it is not shown correctly, it actually looks like this:

enter image description here

I was sure that the vertical bracket was worse than the horizontal bracket before I realized that the vertical one also has middle section with 2 screws:

enter image description here

Now we can also assume that even tho there is a middle section, the hands of the bracket are not actually directly connected to that part, but it still gives some leverage. As we can see from picture 2 or 3, the vertical section is about 40 cm in length or should I say height. This middle section length is about 8.6 cm as seen in picture 3, and it is right in the middle of the 40 cm bracket, with two screws above the middle and beneath it, this I guess gives a much, much better withstanding strength then if it were just the top and bottom two screws.

So how do I calculate this, of course there are some additional equations that might go in, but I would not bother them here as this is the physics section, like what connection is better, does the two screw that are much closer to each other is better, or should I put them horizontally and vertically (like I mentioned, picture 3 is a bit wrong with the screw holes, and there are actually 4, so you can choose whether or not you want to put them:

There are 2 screws on the top and bottom sockets, but four and I can choose from them, like this:

Horizontally,

enter image description here

or vertically,

enter image description here

anyways, like I mentioned I think this is not that important in physics terms, it might be a question for another section, but I think that I needed to include this for you to get the idea if I am missing something and maybe it is possible to calculate if vertical or horizontal screw position will be better.

So the second part of the questions, where we will take the actual examples:

First we know that the horizontal bracket width is about 48 cm, height about 21.5 cm, while the vertical one is about 40 cm with a width of just 7.5 cm.

So again, to visually represent my mind set, this is what I think are the pressure points, with a level of stress to each of them, please correct me where I will be wrong:

enter image description here

I will name the Horizontal Mount as HM, the vertical VM.

HM width = 48 cm HM height = 21.5 cm

VM width = 7.5 cm VM height = 40 cm

So I will just want to ask if you can transition the formulas from the first part of the question and modify them so they are correct in the real life scenario, I already did the sketch and colored of what I think are the pressure points, and please correct me if I am wrong.

If I used some of the terms badly, or use of tags to this post let me know. I am looking for your answer.

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closed as off-topic by JMac, John Rennie, Jon Custer, user191954, Kyle Kanos Nov 1 '18 at 9:58

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question appears to be about engineering, which is the application of scientific knowledge to construct a solution to solve a specific problem. As such, it is off topic for this site, which deals with the science, whether theoretical or experimental, of how the natural world works. For more information, see this meta post." – John Rennie, Jon Custer, Community, Kyle Kanos
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    $\begingroup$ This seems more like an engineering question to me. IMO it seems both too broad, and too focused on this one scenario, to fit well on the Stackexchange Q&A's. Quite a bit of work can go into the design and verification of fasteners and inserts. $\endgroup$ – JMac Oct 30 '18 at 18:06
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Here's the easy answer:

All of the brackets you illustrate are designed to be screwed into the studs in the wall. Using any other sort of mounting WILL pull out of the wall. It will be fine for a while, then you'll bump it one day and "er mah gawd!"

So find the studs, and get some nice long wood screws (2.5" are good) and do it right. Even a 1" screw all the way in will give you >200lbf of pull-out strength, which is way more than even a toggle bolt will get you, so longer ones will do fine even when spaced out by the drywall.

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  • $\begingroup$ I have a vertically perforated hollow wall as I mentioned, this is brick. Also, the thing is I am not sure what force is used, you said pull, but it might also be tensile + shear + diagonal, I am not sure, I also want to know the torque of the thing at 0 distance, or at 1 meter, then 1 meter TV perpendicular to TV and so on, for these I would need a formula. Lastly, like I also already mentioned, there are a lot of products for any material on the market, but I need to know what actual weight this situation of mine puts. I cannot change the wall, so I am searching for a solution. ;/ $\endgroup$ – appwizcpl Oct 29 '18 at 20:50
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enter image description here This is a static problem.

Sum of the forces toward the z axis:

$\sum_{fz}=f_{z1}+f_{z2}-M\,g=0$

With:

$f_{z1}=f_{z2}$

$\Rightarrow$

$f_{z1}=\frac{M\,g}{2}$

Sum of the torques around the x axis

$\sum_{\tau_x}=-f_{y1}\frac{H}{2}+f_{y2}\frac{H}{2}-M\,g\,L_{max}=0$

with:

$f_{y2}=-f_{y1}$

$\Rightarrow$

$f_{y1}=-\frac{M\,g\,L_{max}}{H}$

$f_{y2}=+\frac{M\,g\,L_{max}}{H}$

Data:

M=20 [kg]

g$\approx$10 [m/s^2]

$L_{max}$=0.615 [m]

H=0.214 [m]

$f_{y1}\approx -600 $[N]

$f_{z1}=100$[N]

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  • $\begingroup$ I have some misunderstandings. First, is it that the torque you mentioned intentionally counter clockwise because you are telling me what force the screws/wall gives to counter the torque of the mounting bracket and TV? Secondly why is 2R = 0.467 m (which you probably thought 0.476) but this is the width of the bracket, why not the height? $\endgroup$ – appwizcpl Oct 29 '18 at 20:44
  • $\begingroup$ My mistake it should be the height, sorry $\endgroup$ – Eli Oct 29 '18 at 22:31
  • $\begingroup$ No problem! Although as I already mentioned I am lacking formal physics knowledge and language and I do not understand sometimes why you did something, so if its possible to explain the steps in a bit layman terms after each formula and each statement at least with a short sentence, this would really help me out not messing up. For example, why do you take the height instead of the width or even both? I also have no idea how to declarethe tensile, shear and diagonal force. $\endgroup$ – appwizcpl Oct 30 '18 at 20:19

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