CurtPalme.com Home Theater Forum

rpruen

The story so far...

I have a BD808s sat on top of it's flight case, right in the middle of my 'room of chairs', leaving very little if any space for chairs, let alone anything else.

What I want to do is attach it to the ceiling to get it out of the way. I have no problem with unistrut, and I'll be able to make the support. I had planned to use stainless steel unistrut as it is non magnetic, but as it is not as strong, I'm not sure.

I read the install manual for the barco mount, and it says the ceiling must be able to support 800kg. Do I need to make the support for 800kg, or is that overkill? The projector is just under 100kg, so 300kg should be enough?

I have to do the calcs, but that would mean spanning 8 or so joists (800kg), or 3 (300kg). I have access to the loft, so I was thinking to bolt/screw/clamp 40x60x5mm angle iron to the top of the joists, and then drop 6 M12 stainless steel threaded bars through the ceiling. To the threaded bar I can attach the unistrut, so that it is bolted up tight to the ceiling.

My other problem is that the ceiling is low, and the projector needs to be as close as possible to it. I have looked here and can't see any pictures that have the projector against the ceiling. I was thinking to attach unistrut to the two angle parts on the base of the projector, so the two unistrut rails overhang the projector by a little way. If I then arrange the rails on the ceiling to fit against the projector mounted rails, I can drill and pin the two sets of rails together with 4 10mm pins (secured with 'R' clips or split pins). That should lock the projector in place as close to the ceiling as it can get.

Obvioulsy some of you have done this before, and I would value your input on this. If anyone could point to some pictures of this sort of setup, even if it is totaly different, than that would be a help.

I was going to use the proper fittings, such as 'zebedee nuts' and square washers when fitting the unistrut. Does anyone think it would be a good idea to add some extra safety chains, as the proper Barco mount has?

The screen will be adjusted to suit the projector, so placement isn't so critical, just as long as it's parallel to the far wall, right?

If anyone has any thoughts on this, then I'd like to hear them.

Thanks

Richard

faradayblue · Posted: Tue Sep 09, 2008 1:13 am Post subject:

I just installed a Runco DTV 1100 ( Barco 1209s). I believe the 800kg force you are referring to is the rated strength in the region of the ceiling mount. The margin of safety is highly conservative and protects the manufacturer from any legal action. Most floors are designed to support hundreds of pounds of force whether pushing down from above or pulling from below. I had a steel plate manufactured that spans 3 joists and fastened the steel plate using 4 5/16in x 6in lag bolts on each joist. When installed properly each lag bolt will support several hundred pounds of force. My margin of safety was to use 12 bolts. The manufacturers mount is fastened to the steel plate with 9 bolts. The projector support which is part of the projector is fastened to the projector with only a few small bolts. See my posts on the DTV 1100 installation.

Please note I'm not providing any advise. My risk decisions were based on my own assessment and research for my own installation. I have no problem sitting under the projector.

jkruger · Joined: 24 Oct 2007 Posts: 2435 Location: Carlsbad, CA

I would not spend the extra money on stainless steel unistrut. Once it is installed you will probably adjust out any deflection from the unistrut's magnetism. Every location on earth has different magnetic properties, and the unistrut is not going to be a big deal. Some stainless alloys are magnetic, and the unistrut is made from an alloy that does become magnetic to a small degree. Use the galvanized steel stuff and 3/8" or 10mm rod and it will be stronger than a factory mount. Hang it across three 2"x8" joists and it will be plenty stong. I can send pictures of my mount if you like.

rpruen · Posted: Sun Oct 12, 2008 8:40 pm Post subject:

Thanks for the replies, good info.

I'll go for the normal galv unistrut then, and M10 high tensile threaded rod.

M10 high tensile thread bar have a safe working load of 300kg with a 3:1 safety factor, so no problems with that. As far as the unistrut goes that also will be more than enough, if built properly, to hold the projector.

I still have to sort out the loading for the ceiling, as there is no floor above, the joists are fairly small. I like the idea of a metal plate, or at least an angle iron 'frame' to spread the load. I'm now thinking to weld up a ladder frame from angle iron, this can then be bolted to the top of the joists. That would spread the load over a good area, and prevent any sagging over time.

Thanks again for the input.

Now I just have to sort out getting the job done.

Regards

Richard

Z-Photo · Posted: Mon Nov 10, 2008 3:09 pm Post subject:

The unistrut is made from the magnetic alloys (400/200 series) The nonmagnetic grade is the 300 series - typicall twice the price of the 400 series(think kitchen knives)

jkruger · Joined: 24 Oct 2007 Posts: 2435 Location: Carlsbad, CA

The 400 series stainless steel alloys are not used in unistrut. Standard structural galvanized unistrut (the most commonly used) is made from ASTM A1011 Steel and is not one of the stainless steel alloys, it is a low carbon mild steel. The stainless steel grades used in unistrut are grades 304 and 316, and both can become slightly magnetic thru the cold forming process of rolling the shape. They do not become as magnetic as the steel material, but can become magnetic. Either way you choose to go, the magnetic influence will most likely be shielded by the projector case as they tend to think of these things when they design them. If you want to see how much it affects the deflection, move the unistrut around the pj while displaying a test pattern. I found the ends of the strut had some affect, but when I held the struts in the position that they would be in when installed it had no visible affect. Just FYI

Z-Photo · Posted: Mon Nov 10, 2008 7:49 pm Post subject:

ooops - just did a quick google. No idea why anyone would use 304 over 409 for this application.

But as most of the OEM lift mount are made from low carbon crap steel - I would (and dont) worry about the minimal interaction the mounting material will have over deflection coils operation. Thats what they made adjustments for anyway.