How do you know your Plasma is not going to fall off the wall?

[RichTJ99]

Hi,

I just mounted my 50" Philips plasma the other day using the Omniview U3 XL Tilt wall mount. I hit the center of all 4 studs and the bracket/TV has been up for a few days without incident. This TV is roughly 150 pounds (at least) & if it ever did fall, it would most likely kill anyone in its way.

The length of the omni mount is about 40 inches with the extensions (which I needed). The TV is 55 inches long and the wall studs at my home are 16 inches apart.

The setup came with 4 lag bolts which get screwed into the studs.

Anyway, with everything bolted in, it looks something like this:



------TV--|||---------------==--------------------==---------TV--|||--------



The ---- is the wall mount & the ===== are the studs in the wall and ||| is where the extensions are. TV is where the TV starts & ends. There was no way to get it centered completely as the TV was just a tad to long to mount without the extensions.

Anyway, where the studs are, the lag bolts are secure. If I pull on the extension rods, you can see the metal flex a little however the area where the lag bolts are is dead on solid.

It almost looks a little like if you shake it, the bolt area isnt moving but the ends (because they are 10 inches from the lag bolts) are moving a little. The mount is almost 100% flush against the wall (there is 1 or 2 mm of space on the right side).

It seems to be fully solid, but as my friend who was helping me said, this is one of those things that will fall without warning (if it ever falls).

Of course OCD me gets a little paranoid about that.

Any suggestions on making sure its on the wall solidly? I would rather break the 3k TV than have anyone get hurt. If I start pulling on it to test it, does that weaken things?

Help!!

Rich

[Argetni]

Thats the reason my plasmas are on furniture!

[Doc Tonic]

There are plenty of horror stories about plasmas falling off the wall. Typically nobody is around or its after an earthquake here in CA. We just make sure the seats are far from the plasma and keep our fingers crossed.

[G-force]

My sanus I used is rated for 130lbs my TV is only 83lbs so I think I'm safe. The ratings are usually far less than they can actually hold, but if you can see it flex that might worry me.

The sanus mount is pretty thick gauge steel and seems solid as a rock, I highly doubt I could ever get any flex out of it.

Just take extra time to place your lag bolts, I use very thin nails to pilot hole and find dead center of studs before I drill. Also listen closely when tightening down your lag bolts for any splintering. Also if your bracket is 40" wide couldn't you fasten it to 3 studs instead of just the 2.

If would also advise not to remove and reinstall the bracket once it's up. You want that initial bite of the lag bolts for strength. I think once the lag bolts come out and then go back in those same holes you'll lose some of the strength.

If I had a set that weighed 150lbs I might think twice about wall mounting it, unless of course that wall was costructed to hold such a load.

[JohnS-MI]

Another vote for mounting across 3 studs; 32" of the 40" are then well supported. How far apart are the hooks on the tv bracket that engage the wall plate? Probably close to that 32" dimension.

[esanger]

Aren't studs normally either 16", 20 or 24" across? Even at 16", 3 across is spanning 48"...

[pj2004]

Well actually if they're 16" on center you'd have two outer ones 32" apart (on center) and then one in the middle of those two, so you could do 3 studs. At first I was thinking the same thing.

[MNbri]

sounds to me like all you're getting is a little play from using the extensions?

don't worry about it, just enjoy your panel :)

[tlgpa]

[QUOTE=RichTJ99]Anyway, where the studs are, the lag bolts are secure. If I pull on the extension rods, you can see the metal flex a little however the area where the lag bolts are is dead on solid.

It almost looks a little like if you shake it, the bolt area isnt moving but the ends (because they are 10 inches from the lag bolts) are moving a little. The mount is almost 100% flush against the wall (there is 1 or 2 mm of space on the right side).[/QUOTE]
Did you follow the instructions exactly? Fill out the warranty card? If so, you don't have anything to worry about. The movement you're seeing is most likely flexing of the bracket. It's a static application. Unless you're in a mobile home, it shouldn't be moving. Also, looking at your diagram, your lag bolts seem pretty close to the center. Do you have another stud you can catch closer to the ends? If so, and you're really concerned, go to a hardware store and pick up a few extra lag bolts.

It seems to be fully solid, but as my friend who was helping me said, this is one of those things that will fall without warning (if it ever falls). What did he use for the basis for this determination? If you've got 4 lag bolts, and you hit them in the center of studs, it's never gonna fall.

Of course OCD me gets a little paranoid about that. For your paranoia:
http://www.techdata.com/techsolutions/digitalenvironments/files/OmniMount%20FP%20Wall%20Mounts%20handout.pdf#search='lag%20bolt%20stud%20pull%20strength'
I’m concerned about single stud mounting a heavy Plasma display. Is single stud mounting really safe?
There are two primary factors that determine mounting integrity in a wooden stud application:

1. The shear strength of the mounting bolts used
2. The pull-out strength of the bolts when screwed into a wooden stud

Shear strength is a measure of how much force it takes for the load a bolt is suspending to shear, or cut through that bolt. OmniMount provides four 3/8" by 2 ½” steel lag bolts with each mount, and the shear strength of these bolts is 8820 lbs. each. This means that a single bolt will not shear under the weight of a plasma display.

Pull out strength is determined by how far a bolt is driven into a wooden stud. A 3/8” bolt has a minimum pull-out or 235 lbs. for every inch of thread engagement. Our 2 ½” lag bolts provide 587 lbs. of pull-out strength per bolt.

So, considering all of the above, if only 3 bolts are used to secure the mount to a stud, and those bolts are driven in to their full length of 2 1/2", [COLOR=Sienna] then you have over 1700 lbs of pull out strength. This is enough weight capacity to support a small car[/COLOR].

Any suggestions on making sure its on the wall solidly? I would rather break the 3k TV than have anyone get hurt. If I start pulling on it to test it, does that weaken things?
Do not start pulling on anything. You may crack your drywall or bend the bracket.
Like I mentioned, if possible, add more lag screws closer to the ends of the mount.
Did you use a stud finder to locate the center of your studs? In not, get one (they're cheap) and make sure you lag bolts are centered.

If you can't hit another stud, get some drywall anchors and secure the ends of of your mount with them.
http://www.simpsonanchors.com/images/product/sure-wall-main.jpg

This will eliminate the flexing you're seeing.

http://www.simpsonanchors.com/images/tables/SUREWALLLOAD.gif
4 of these will give you up to an additional 80lbs tensile/260lbs shear load.
[COLOR=Sienna]In addition to the 35,280lb/2,348lb load strength of the lag bolts you have[/COLOR].

[RichTJ99]

[QUOTE=MNbri]sounds to me like all you're getting is a little play from using the extensions?

don't worry about it, just enjoy your panel :)[/QUOTE]


That is what it feels like. The bolts are solid in the wall.

After remeasuring, the mount itself is 29 inches wide with two 6" long extension rails. Due to the size of the TV, only one side is using an extension rail (the other is using the regular part of the 29 inch mount (there is no way to get both sides on the inside or outside of hte mount.

The metal part of the mount itself seems to be bending a bit.

If the mount itself is 29 inches, the bolts are about 5 inches from either end, so the mount is held secure in a 20 inch area (on the inside).

The pink in the JPG is where the bolts are attached. The blue on the right is where the mount is lifting slightly.

If I pull on that extension bar, the metal itself is about to move but the bolt in the wall is not budging one bit.

That is what I am trying to see if I should be concerned about.

[kbp]

The analysis of the applied forces and the failure modes are not nearly that simple as the previous poster states, but the point that four lag bolts are not the weak link is correct. It seems like the mount is flexing a bit.

[B1g Bleu]

A couple of toggle bolts (maybe even 1) should stiffen that end.

[tws1972]

Well, I'm no expert but I did install my own 42" plasma on my wall (with help from my Dad) and I have to say, I've NEVER worried about it falling down. I've had it up there for 2 years now. When we installed the Sanus wall mount, we both tried to hang from the edges of the wall mount to just see how solid that thing was. I have to say, it doesn't seem like anything can bring that thing down...unless of course we have a catastrophic earthquake (I live in L.A.)...in which case, I will just be happy to be alive to witness my plasma on the floor. I really don't think you have anything to worry about. Like some said, ENJOY THE PANEL!!!

By the way, I also helped install 2 other plasmas for 2 different friends. Same type of setup...and same type of solid install.

[DAB]

Rich, how old is your Plasma- 150lbs wow.

I just installed a Omnimount UCL-X wishbone( weight up to 200--- tv is 100lbs), it has three bolts pre-side. Even at full extension it does not even wiggle. If you place the bolts in correctly you should be fine even in Quake county like me.
the real question is ,is what is your mount's weight capacity?
db

[mattsoft]

After bolting the mount to the wall, I actually grabbed onto the mount and pulled myself up -- all 190lbs of me -- and it stayed just fine. Figured if it could hold me, it could hold a plasma TV. :D

[tlgpa]

[QUOTE=kbp]The analysis of the applied forces and the failure modes are not nearly that simple as the previous poster states, [/QUOTE] Actually it is that simple. Assuming the 4 lag bolts are screwed properly into the studs.

Unless the TV will generate 35,280lb of shear force, the bolts won't break.
Unless the TV generates 20,000 lbs of tensile force, the bolts won't break.
Unless the TV generates 2,348lb of pull force, the bolts won't pull out of the studs.

Unless the studs pull out of the wall (or the wall falls over), the TV won't fall.

[Naylia]

Well as long as the mounting bracket doesn't break....I think that's what kbp meant.

[No_Towel_Lint]

We have a lot of plasmas mounted in our showroom using the omnimount U3 tilt mount and none of them have had any problems. Of all the ones we have mounted, the Philips is the only one that requires the extensions but it too has hung for months without any problems.

[hammick]

In late 2001 I mounted a 50" pioneer in my office conference room (yes it was expensive). The walls had metal studs. I used a heavy tilt mount (the kind that has a screw from the top to tilt) and was concerned that I could only mount to one stud if I wanted to center it on the wall.

I cut out a rectangle piece of 3/4" plywood wide enough to mount to two studs with four lag bolts. I think I bolted the mount to the plyboard and used big washers on the back prior to mounting the plyboard but I cannot remember for sure. I do know that I was comfortable with the 3/4" plyboard carring the load across two studs and I was able to hang on the mount and shake around without any movement of the mount or the wall. I probably weighted about 170lbs at the time. This was a very heavy TV that took three people to safely lift onto the mount.

If you are concerned cut a piece of plyboard to distribute the load. Paint it the same color as the wall and you will never notice it. Only negative is that your TV will be 3/4" further from the wall.

[kbp]

[QUOTE=tlgpa]Actually it is that simple. Assuming the 4 lag bolts are screwed properly into the studs.

Unless the TV will generate 35,280lb of shear force, the bolts won't break.
Unless the TV generates 20,000 lbs of tensile force, the bolts won't break.
Unless the TV generates 2,348lb of pull force, the bolts won't pull out of the studs.

Unless the studs pull out of the wall (or the wall falls over), the TV won't fall.[/QUOTE]
No, there are several mistakes and omissions in the analysis of the forces applied to the bolts and the capacity of the bolts to resist. Again.....this doesn’t mean that lag bolts are not adequate. I’m just pointing out that your values are wrong and that people should realize they are not nearly that high.

The allowable shear value you give is for the bolt material. This is NOT the governing shear failure mechanism. The actual shear capacity for a lag bolt is governed by failure of the wood holding the bolt, not the bolt material. This is different than pullout failure. Secondly, a 3/8" dia x 2½" long lag bolt installed through a metal mount and through ½" of drywall will only be embed about 1 7/8" into the stud, not 2½". Taking this into account, the allowable shear for one bolt in a typical Spruce-Pine-Fir wood stud is about 120 lbs (119 lbs, actually) to support dead loads, like a TV. This neglects bending of the bolt in the gap (drywall space) between the mount and the stud face, which technically should be considered. Assuming the four bolts are equally loaded (which would be very unlikely in a single stud mount) the total allowable shear force would be about 480 lbs. As I said, still plenty, just nowhere near 35,280 lbs.

Pullout value, as you correctly state is 235 lb per embeded inch, for a Spruce-Pine-Fir wood stud. However, it is based on embedment of the THREADED portion of the lag bolt, not including the tapered tip nor the unthreaded portion of the shank. For a standard 3/8" dia. x 2½" lag bolt this length is just over 1½". The pullout capacity in a typical Spruce-Pine-Fir wood stud is then 352 lbs per bolt. While the weight of the TV is trying to pullout the anchors, it is only the top ones that are actually resisting this force. The mount is actually pushing INTO the wall at the bottom, while trying to pullout at the top. Therefore, the pullout capacity is 352 lbs. per /bolt x 2 bolts = 704 lbs. Again, as I said, perfectly adequate, just not 2348 lbs.

Things also not taken into account which will also reduce the allowable load.....if the single stud is not centered on the TV, the forces, the shear and pullout, will not be distributed equally to all bolts. This would make the total capacity of installation somewhat less than the sum of the maximum capacity of all the anchors. There is also an interaction of stresses, when both a shear and a pullout load are applied to a bolt at the same time, which reduces the allowable load.

Simple, right? :)

[RichTJ99]

Are the omni mount bolts 2 x 3/8? Should I be getting a 3/8 lag bolt for the sheet rock (or whatever the right term for the bolt is for the sheet rock?

[QUOTE=tlgpa]Did you follow the instructions exactly? Fill out the warranty card? If so, you don't have anything to worry about. The movement you're seeing is most likely flexing of the bracket. It's a static application. Unless you're in a mobile home, it shouldn't be moving. Also, looking at your diagram, your lag bolts seem pretty close to the center. Do you have another stud you can catch closer to the ends? If so, and you're really concerned, go to a hardware store and pick up a few extra lag bolts.

What did he use for the basis for this determination? If you've got 4 lag bolts, and you hit them in the center of studs, it's never gonna fall.

For your paranoia:
http://www.techdata.com/techsolutions/digitalenvironments/files/OmniMount%20FP%20Wall%20Mounts%20handout.pdf#search='lag%20bolt%20stud%20pull%20strength'
I’m concerned about single stud mounting a heavy Plasma display. Is single stud mounting really safe?
There are two primary factors that determine mounting integrity in a wooden stud application:

1. The shear strength of the mounting bolts used
2. The pull-out strength of the bolts when screwed into a wooden stud

Shear strength is a measure of how much force it takes for the load a bolt is suspending to shear, or cut through that bolt. OmniMount provides four 3/8" by 2 ½” steel lag bolts with each mount, and the shear strength of these bolts is 8820 lbs. each. This means that a single bolt will not shear under the weight of a plasma display.

Pull out strength is determined by how far a bolt is driven into a wooden stud. A 3/8” bolt has a minimum pull-out or 235 lbs. for every inch of thread engagement. Our 2 ½” lag bolts provide 587 lbs. of pull-out strength per bolt.

So, considering all of the above, if only 3 bolts are used to secure the mount to a stud, and those bolts are driven in to their full length of 2 1/2", [COLOR=Sienna] then you have over 1700 lbs of pull out strength. This is enough weight capacity to support a small car[/COLOR].


Do not start pulling on anything. You may crack your drywall or bend the bracket.
Like I mentioned, if possible, add more lag screws closer to the ends of the mount.
Did you use a stud finder to locate the center of your studs? In not, get one (they're cheap) and make sure you lag bolts are centered.

If you can't hit another stud, get some drywall anchors and secure the ends of of your mount with them.
http://www.simpsonanchors.com/images/product/sure-wall-main.jpg

This will eliminate the flexing you're seeing.

http://www.simpsonanchors.com/images/tables/SUREWALLLOAD.gif
4 of these will give you up to an additional 80lbs tensile/260lbs shear load.
[COLOR=Sienna]In addition to the 35,280lb/2,348lb load strength of the lag bolts you have[/COLOR].[/QUOTE]

[RichTJ99]

The TV is the 50 inch Philips plasma that was on sale at costco last week. p50f2200 (something like that). The mount is the Omnimount UXL-T (XL) & holds up to 200 pounds.



[QUOTE=DAB]Rich, how old is your Plasma- 150lbs wow.

I just installed a Omnimount UCL-X wishbone( weight up to 200--- tv is 100lbs), it has three bolts pre-side. Even at full extension it does not even wiggle. If you place the bolts in correctly you should be fine even in Quake county like me.
the real question is ,is what is your mount's weight capacity?
db[/QUOTE]
The

[DAB]

Rich, i looked up your mount-their are many- i did not see this model # UXL-TA(CEL). but the UA3-TA.
If omnimount state it will hold up to 200lbs. with correct mounting. it should work. but make sure all your bolts have hit the center of your stud-straight in. If your bolts are on the very edge of the stud -bolt hoding could be a future -issue. Onmi supply( at least for my mount) the "correct bolts" for the job.(think warranty here). One criticism of omin's extended arm mounts were they where slight wabbly. That is why i went w/ the wishbone series.

[tlgpa]

[QUOTE=kbp] I’m just pointing out that your values are wrong and that people should realize they are not nearly that high. [/QUOTE]
Not my values. They come from Omnimount. I did add the tensile strength of the bolt as reference.

The actual shear capacity for a lag bolt is governed by failure of the wood holding the bolt, not the bolt material. This is different than pullout failure.
And as the wood fails, the bolt will pull out. The bolt will never shear since it is far stronger than the lumber. The "shear load" refers to the amount of vertical force required to pull a screw out of lumber in a direction perpendicular to the screw's axis. Nothing actually "shears".

Secondly, a 3/8" dia x 2½" long lag bolt installed through a metal mount and through ½" of drywall will only be embed about 1 7/8" into the stud, not 2½". I believe this is a typo by Omnimount. Their instructions http://www.omnimount.com/pdf/U3Tinst.pdf (http://) call for a 3/8 x 3 ½ LG bolt. Which would give 2 ½ of engagement, not actually a 3/8 x 2 ½ bolt. Thus 235 lbs x 2 ½ = 587 lbs pullout.

While the weight of the TV is trying to pullout the anchors, it is only the top ones that are actually resisting this force. The mount is actually pushing INTO the wall at the bottom, while trying to pullout at the top. Therefore, the pullout capacity is 352 lbs. per /bolt x 2 bolts = 704 lbs. Again, as I said, perfectly adequate, just not 2348 lbs. This is an incorrect analysis. While the cantilever effect will cause the bottom of the bracket to be in a compressive force against the wall, and the top to be in tensile, the bolts will all be in tensile. The actual pivot point of the bracket is below the bottom row of bolts. And it appears to be approx. 2" below.
http://img372.imageshack.us/img372/7158/bracket9fl.jpg

http://www.roymech.co.uk/images5/bolt_4.gif
Each bolt withstands a tensile force of Fnt = ( Fv. Rv + Fh. Rh) . Vn / (V12 + V22....Vn2 )


Granted, the moment from the pivot to the bottom bolts will be less than from the moment to the top bolts, but all will be in tensile. It will require 587lbs of pull force on each of the bolts. The top bolts can't pull out if the bottom ones don't pull out as well.

[tlgpa]

[QUOTE=RichTJ99]Are the omni mount bolts 2 x 3/8? Should I be getting a 3/8 lag bolt for the sheet rock (or whatever the right term for the bolt is for the sheet rock?[/QUOTE]
I believe the Omnimount bolts are 3/8 dia x 3 1/2" lg.
Do these match what you have? http://www.omnimount.com/pdf/U3Tinst.pdf
These would be for mounting to the studs.

If you're looking to help secure the bracket from pulling away from the drywall (IN ADDITION TO THE LAG BOLTS), you would want drywall anchors.
http://www.simpsonanchors.com/Catalog/mechanical/sure-wall/
THey come with everything you need. You can get them at any hardware store, walmart, etc.

[kbp]

The allowable shear load for the bolted connection are as I posted. If the lag bolts are actually 3½" long then the allowable shear load would be 546 lb/bolt. The failure mechanisms of a bolted wood connection due to a shear force is complicated and has been extensively researched. There are actually six modes of shear failure, each of which is checked to see which will govern. These modes take into account, among other things, the crushing of wood against the bolt which results in slippage of the connection. At this point, the connection has failed, long before the bolts pull out and before the bolt material shears through. As mentioned before, the allowable shear load on any bolts also in tension would be even less, due to interaction of stresses.

The diagram with the pivot point is not really a valid analysis for this case. First, the model should have a compression block at the bottom, which is the area necessary to distribute the compression force to the drywall without failing (crushing) it, rather than a pivot point. In the posted diagram, the bottom bolts would be within this area, the compression block, and would not be in tension. Also, your analysis assumes a relatively stiff mounting bracket to distribute the moment proportionally to the anchors based on their moment arm. In reality, most mounts will flex too much for this to be a valid assumption.

Secondly, in looking at the posted photograph of mount it is clear that the compression force is applied directly to the bottom rail, while the tension force is applied directly to the top rail. The top rail spans horizontally and transfers the tension directly to the two top anchors only.

Again, my point is that while most lag bolted mountings are perfectly adequate, the safe loads are not as high as earlier stated, and determining the actual allowable capacity is not necessarily obvious or simple.

[mbryda]

Simple.

I hung our 42" Philips across 3 studs, which in our house (for whatever reasons) appear to be 2x4's turned 90 degrees so that the stud is 4 inches on the wall side and 2 in. deep.

I found the center of the studs, drilled and anchored all 6 bolts to wood. Put the mount up, and hung from the frame (I'm 6"2', 275lb). Didn't budge or even make any noises. Double checked the bolts.

Put the puny 110lb Philips up and I know it's not going anywhere unless the wall comes down. In which case we'll have bigger problems.

[kbp]

Yep, that’s a good way to go. 6 lag bolts should easily hold 275 pounds.

[Falhawk]

do you think a single stud could hold a 60 pound 37" plasma?

[74Capri]

That's why i let them install it.
You just never know.

Kind of hope it does, piece of junk anyways.

[LXIX]

Why are people so concerned with this? For years we have put CRT TVs onto improper TV stands and I cannot remember a single concern about TV's tipping. Even when Circuit City had a TV fall over onto a child, consumers never changed their habits when it cam to mounting a CRT TV (surely a CRT display would be safer if it were bolted to a stud by a strap).

I own speakers that weigh 60lbs each and if tipped would do damage to whomever they hit. My in-laws 32" Sony XBR (162 lbs) is on a generic stand with no straps holding it into place. I have never been worried about these items falling and hitting me or my family.

You have just mounted a 150lb TV to a wall with a minimum of 3 3" bolts and you are concerned about it falling over? I think your paranoia is without merit. You should have been more concerned when your old TV wasn't bolted to anything and it stood on a stand that probably weighed half as much as the TV.

Just my $.02

[kbp]

[QUOTE=Falhawk]do you think a single stud could hold a 60 pound 37" plasma?[/QUOTE]
Yes, it’s very possible, but dependant on the mounting hardware and location of the plasma relative to the stud. Personally, I would prefer hitting two studs, but I understand sometimes this isn't possible.

[Falhawk]

heh 200 year old house

post and beam, I'm hoping that there's even 1 stud (since it is a wall that actually has another wall on the other side of it jutting out perpendicularly)

[trailingedge]

[QUOTE=mbryda]Simple.

I hung our 42" Philips across 3 studs, which in our house (for whatever reasons) appear to be 2x4's turned 90 degrees so that the stud is 4 inches on the wall side and 2 in. deep.

I found the center of the studs, drilled and anchored all 6 bolts to wood. Put the mount up, and hung from the frame (I'm 6"2', 275lb). Didn't budge or even make any noises. Double checked the bolts.

Put the puny 110lb Philips up and I know it's not going anywhere unless the wall comes down. In which case we'll have bigger problems.[/QUOTE]

What kind of lag bolts did you use in the wall mount? 3/8" X 2" long? Or did you have to use even shorter lag bolts? My mother has the same situation, and I'm trying to figure out how to safely secure the TV to these studs. I will also use a total of 6 bolts.

[meitzner]

Ok, I mounted the TV myself using the articulating Vantage Point single stud mount (See attached pic)...this is holding a 26" HPLC2600N LCD TV that weighs in under 50 lbs, but the mount is rated at 100lbs. But now, directly underneath the stud where it's mounted the drywall and paint is cracking. I followed the instructions exactly, but am now obviously concerned that something is wrong. The crack extends pretty much from the stud that the TV is mounted to halfway to the next stud in either direction, so it's about 16-20" long. It's not too wide right now, but it's noticeable. I don't swivel the TV much anymore but I used to quite a bit (but then again, that's what this particular mount was designed for). Any suggestions? Do you think it's okay to repaint this crack or should I caulk it or what? It's in a pretty prominent spot in my bedroom, so whatever I do has to look good. DO you think it'll get worse or is the wall or TV in any danger? Thanks a million for any help.

[whityfrd]

im currently laying out plans for my own tv stand. im adding a wood wall extension to the back of it like some plasma furniture so i dont have to tear up the wall. and the wife will be happy too!