question on materials - on flexi rack? (1 Viewer)

[Raphael O]

i want to build a flexi rack for my 32 inch toshiba TV and this thing weigh a ton (approx more than a hundred lbs ,maybe around 130).

i want to know if these supplies will work to hold it .

the rack will be around 40 inch wide ,20 inch deep and 24 inches high .
i will use 3/4 threaded rods - six of them for support - two on each side and two in the middle.
there will be 3 shelves - the lower would be around 12 inches and the upper will be whet is left over .
i want more room at the lower for the avr 8000.

what thickness mdf do u guys think i should go for?

would this design be able to support the tv ok?

need your input guys ok

 

[David Ison]

don't use mdf for the shelves they will sag and eventually break holding this much weight on such a wide span, use 3/4" plywood.

 

[Brian Knauss]

There was a thread going on about a week or two ago where the guy made a flexy, and it sounds like the same design you're going for. I think curved flexi might be in the title of the thread

 

[Raphael O]

tnx for the info guys - even if i have 6 points of support (6 rods) wont cut it huh.

ill look around and search for different materials to use.

 

[Wes Nance]

I disagree with David. If you have the 2 support posts in the middle, I don't think you will have any problem at all. Make sure that the rack is supported from the floor right under those posts, so the whole rack doesn't sag in the middle. If you were just sitting the rack on the threaded rods at the bottom, this won't be an issue. But some people put casters, ball transers, etc., on the bottom, so you would need to make sure you had those under the middle rods as well, not just the end ones.

I have a Sony Wega 27" TV, which is probably not as heavy as your Toshiba, but close- it's easily around 100lbs. I have a flexy temporarily assembled, with just the 2 posts on either end of a 3 shelf rack, 48" wide by 24" deep, sounds close to your design. It was sagging in the middle by about 3/4". I will put one center post on it to take care of that, but in the meantime I just cut 2 pieces of MDF to place inbetween the shelves to prevent the sag. Now it sags around 1/8", but there is no center support to the floor, so that's why it sags still.

So when I add the center pole, and have it supported to the floor in the center, it shouldn't sag at all.

If you build your rack right, you can probably get up and jump on it, and it will hold no problem.

Others have more flexy experience than I do, so I hope they chime in.

Wes

 

[Wes Nance]

By the way, I only used 5/8" rods, too. 3/4" should be really strong. . .

Wes

 

[Raphael O]

tnx again for the info
ill make sure all 6 supports are on the floor even .

 

[David Ison]

I will concede I may be wrong about the sagging, why take a chance when spending a few dollars more will give you peace of mind?

 

[Wes Nance]

David,

I think that plywood could still sag without a center support over a 4 foot span with a 150 lb tv on it. With a center support design that is anchored to the floor, there is no way that MDF is going to sag over a 2 foot span when the TV is directly over the center posts.

I would prefer MDF for cosmetic reasons. I routed a decorative edge on my shelves- plywood would not work for this. MDF is also easier to get a smooth paint result because it can be finished so smooth.

This is all my opinion, of course, but I have a 3 shelf flexy in my basement that gives me some idea that it might work. . .

Wes

 

[Ron-P]

Here is a pic from my old Green Room theater with a flexy I built for my 200lb RPTV. It is constructed with 3/4" MDF and has 6 legs, 4 around the perimeter and two in the center. I had no problems with sagging. The two center rods were cut to match the height of the top shelf.
Sorry the pics not that great. I don't have any other pics of the rack online anywhere.
Peace Out~

 

[Raphael O]

ron , pics are not working - can you email it to me at [email protected]

 

[Ron-P]

Sorry about that. I just read the disclaimer over at AVS and did a no-no.
HERE is a link to my pics over at that site. You'll see the pic over there along with others of my old room. I do have better ones I can email you later tonight.
Peace Out~

 

[Ryan Schnacke]

"David,
I think that plywood could still sag without a center support over a 4 foot span with a 150 lb tv on it."
Huh? He didn't say anything about removing the center support. And 40 inches is not 4 feet.
I built a very similar flexy. 20 deep x 42ish wide to hold a 32 inch JVC television that weighed 90 - 100 lbs. But I used 3/4 plywood. No issues for the 1 year I used it. You can see pics at
http://photos.yahoo.com/ryan_schnacke/
I'm in the process of building a flexy to enclose my 47" widescreen.

 

[Wes Nance]

Ryan,

Is that 3/4" birch veneer plywood? What's the cost difference compared to 3/4" MDF?

don't use mdf for the shelves they will sag and eventually break holding this much weight on such a wide span, use 3/4" plywood.

I assumed he had to be speaking about the whole span of 40", because there's no way MDF is going to sag and break over a 20" span.

I accidentally used 4 feet, because that's what my rack is; sorry for the confusion.

I think that your rack looks great, and surely that 3/4" veneer plywood is one alternative, but I don't think the reason to use it is just because the MDF is going to break, as that's not really the case.

Wes

 

[Ron-P]

Raphael, no need to send you pics, mine looked identical to Ryan's except that my 2 center supports were inset about 6" instead of being right on the edge and I did not put wheels it.
Peace Out~

 

[MarcVH]

You may find it helpful to consult a table of MDF strength. Sounds like you'll be fine.
There are trade-offs, of course -- having the extra metal rod in the center means you lose the option of putting your center speaker under the TV, if that matters to you, or adjusting the system to make your TV higher or lower later.
I have a Flexy with a 38" span supporting my 140-lb TV. Normally that wouldn't be strong enough, but the MDF is reinforced with a couple of 2x4s. I'm sensitive to the matter because I just re-adjusted my whole system to raise my TV 3 inches higher, and make a slightly larger component shelf for outboard amps to have enough breathing room. One key advantage of the Flexy architecture is that you can change it later pretty easily.

 

[Ryan Schnacke]

Wes,

"Is that 3/4" birch veneer plywood? What's the cost difference compared to 3/4" MDF?"

Yep. Its about $45 for a 4x8 sheet vs about $17 for MDF. Plus you've got to buy the veneer edging for about $5 - $6 for 25 feet. Plus your choice of finish (stain and polyurethane in my case) but the MDF would need some sort of finish so this isn't really extra. Definitely more expensive and definitely more work - veneering the edges seems like a small job until you get started. But it must not be that bad since I'm working on my 3rd using veneer ply.

"I think that your rack looks great"

Thanks. I wanted to try something other than painted MDF. BTW I do recommend using some sort of cushioning washers. I used only metal washers on my first 2 flexys and one of them (the TV stand) creaks every now and then.

Marc,
Great link! I didn't even know there was LD, MD and HD versions of MDF. I wonder what the stuff at Home Depot/Lowe's is.

 

[Arthur_King]

What I would suggest is something more robust. Create a "strong shelf" (tm) for example, involving 2 sheets of MDF and 2x4 pieces on their side between them. In essence make a "box" that increases the strenght of that shelf. Then put the one rod in the middle, or put some metal L-brackets along the back.

There are several ways of strenghtening your shelf. I would say, however, that just one shelf of MDF, without at minimum a center bar for support will NOT be enough for ya.

Daffy Arthur King