But the point you conveniently missed is that most of the weight (and force) is still downwards on the bottom fixings.
How much does the telly weigh? If it's sufficient that the "turning moment" on the top fixings is 30kg as you stated then I would stand it on the floor!
MBQ
messagenews: snipped-for-privacy@z66g2000hsc.googlegroups.com...
But the point you conveniently missed is that most of the weight (and force) is still downwards on the bottom fixings.
How much does the telly weigh? If it's sufficient that the "turning moment" on the top fixings is 30kg as you stated then I would stand it on the floor!
MBQ
This part of the thread came about as a result of someone stating that it was common to find large screen CRT sets sitting on free wall-mounted shelves. Such a TV weighs *considerably* more than 30kg and, short of using expansion bolts direct into a brick or block wall, I for one would not want to risk hanging one on the wall via shelf fixings. On the other hand, a largish - say 42" - plasma TV does weigh around 30kg which, whilst still a significant amount, is nothing like as much as a large CRT set. Further, the many types of wall mounting brackets for these have multi fixing points over a (relatively) large area to spread the load on the wall and the fixings. Even given all this, I still stand by my original contention that fixing one to an ally framed wall, requires careful consideration, and planning of the type and locations of the fixings.
As far as most of the weight being borne by the lower fixings, this is true, but only emphasises the point that the load is not evenly spread across the fixings, as might be the 'obvious' conclusion. Further, the turning moment will also ensure that a fair bit of the downward force is also turned inwards, so between the top and bottom fixings, it will be trying to turn the wall into an "S" shape.
Don't get me wrong. I fully accept that many people do fix plasma and LCD sets to all types of wall, and for the most part, successfully. I just felt that with the type of wall under consideration in this case, some careful thought needed giving to what, on the face of it, would seem a straightforward job. Especially as the OP was going to be doing it as a favour for someone else ... d;~}
Arfa
Looking at the threading, it seems that that "someone" was me. I did say something like that, but not the "large screen" bit, which I think you imagined.
In the message I was replying to you said "nothing much heavier than a mirror used to get hung on a wall before the advent of flat screen TV sets". In my experience your average portable (not "large screen") TV, of the sort that is commonly wall-mounted, is rather heavier than your average mirror. Additionally its centre of gravity is considerably further from the wall, making it more difficult than a mirror to mount securely.
No, read the bit of the thread I left quoted above. It was s imple comparison of weight. No one said anything about it being common to wall mount large CRt sets
I agree, but if the telly only weighs 30kg, the *outward* force will be nothing like 30kg.
MBQ
Well I'm sorry, but I think that's being a bit silly then. :-) The entire thread had been about hanging bloody great plasma TV sets on an ally framed wall, and then you came in with your post about CRT sets. The exact bit that you were replying to was a comment made by me in regard to Kevin saying that his new 42" flatscreen was lighter than his old 32" CRT set. I was pointing out that such a CRT set size was not typically fixed to a wall, and you came back with your statement about fixing shelves to the wall, and then sticking the TV on them. So whilst you do not refer to large screen CRT sets directly, as you were replying to a comment that *was* specifically in their regard, then the inference has to be that you too were talking about large screen CRT sets, and it was not something that I "imagined".
Of course portables get put on shelves in kitchens and bedrooms, and always have done, but then they don't weigh tuppence ha'penny. You can raise one over your head on one hand. Any shelf that you put one on will be secured by probably 4 or more fixing points, as will any custom arm-supported mount, so the relatively light weight of the set will be reasonably well spread around the fixings, even given that its c of g is several inches out from the wall. However, that said, unless it's fixed properly to a 'weak' wall such as one that is plasterboard faced, the result could still be that the top fixings get pulled out.
I do accept your point about mirrors though. It was a somewhat 'throw away' comment on my part, and probably not properly thought through in regard to the whole scenario. But many modern mirrors are quite heavy - a warehouse local to me sells many designs that are 4 foot or more across - and these probably weigh as much as a portable TV, and get hung on one or maybe two screws, so probably exert as much destructive force on the fixings as the TV shelf, even though the c of g is closer to the wall.
Arfa
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