How strong IS MDF?

Discussion in 'Archived Threads 2001-2004' started by James Bergeron, May 17, 2002.

  1. James Bergeron

    James Bergeron Supporting Actor

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    I bought a piece of 1/2" MDF I got it to hold my PJ on my ceiling (CRT approx 140lbs) It will be secured with MANY screws in 3 places. Along the short edge, 3 rows basically like beams accross the MDF with 2.5" screws.

    I am then going to bolt my pj mount to the MDF with 4 bolts, the 4 bolts will all be fairly close to the screwed edges.

    What do you "wood experts" think. They guy at home depot seemed like he knew what he was talking about, he said it should be no problem.
     
  2. Greg_R

    Greg_R Screenwriter

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    MDF is not very strong. It is used in speakers because of it's dampening properties. For strength I would use 3/4" baltic birch ply or marine grade plywood. Also, MDF can tear out more easily (so screws have less holding power). MDF is cheaper but is also heavier (vs. quality ply). Not all Home Depots sell BB ply.

    But is MDF strong enough? I would at least go with 3/4" MDF (vs. 1/2"). For peace of mind I'd spend the $$$ on some good ply (you're supporting a pricey PJ). I assume you've also read about the unistrut mounting solution?
     
  3. James Bergeron

    James Bergeron Supporting Actor

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    Yeah I've read about the uni-strut but I have the factory mounting bracket [​IMG]
    I WAS going to go with 3/4" plywood, but the store would only sell me an entire 4x8 sheet! I had NO means of cutting or moving it for that matter.
    I guess I'll go with my original Idea. Attached the MDF and bracket and hang from it. If I fall or shake or hear funny noises I go get plywood. Otherwise I'm happy.
    Or maybe I can find a store that will provide me with a half sheet of 3/4" plywood, and cut it to my likeing.
    The MDF cost me $3 if I don't use it, it's not like I lost my shirt!
     
  4. James Bergeron

    James Bergeron Supporting Actor

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    Ok.... Maybe I should dispose of the MDF and spend $15 I found a place that will cut me a piece of 3/4" Fur Ply for $15.

    This should be PLENTY strong..... I hope!
     
  5. Kerry Hackney

    Kerry Hackney Stunt Coordinator

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    I wouldn't want to put "my" projector on a 1/2" MDF shelf hung from the ceiling. Go with the plywood...
    [​IMG] If I had a projector that is....
     
  6. Pete Mazz

    Pete Mazz Supporting Actor

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    If you use the appropriately sized bit when pre-drilling and some wood glue, the MDF should be fine. In fact the glue will be stronger than the screws. Be wary of fir ply. Some of it is only 5 ply, and rather unstable. Plywood doesn't hold screws very well either(into an edge), and glueing is only as good as the lamination bond, which in some plywood is not that great. Couple this with the fact that glueing butt joints with plywood only bonds well onto the long grain layer of the edge(end grain butt joints are very weak).

    If you can get a decent particle board, it would work better for this application.

    Pete
     
  7. James Bergeron

    James Bergeron Supporting Actor

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    I'm just FULL of ideas today. I was just talking to a co-worker and he was saying, what's wrong with 1x2?

    or 1x4 strapping for that matter. What's the difference? I'm only attaching it in 4 places (the projector and mounting bracket) so will having plywood or something similar really be of benefit? What if I attached strips of 1x4 strapping on my beams and then mounted the projector on that?

    These are just ideas.... what do you guys think? When I go to a lumber store they look at me funny when I say I want to hang a 140lb projector from my ceiling. They haven't the foggiest what would be good.
     
  8. Pete Mazz

    Pete Mazz Supporting Actor

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    Now I see what you want to do.[​IMG]
    In that case, solid wood would be best. Poplar would be a good choice, bang vs buck. HD sells it. Paints well, medium hardness, and stable.
    Pete
     
  9. Andrew Low

    Andrew Low Extra

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    James, go to Rona in Ottawa (merivale & huntclub). They sell smaller cuts of most wood.

    The recommendation is to use a board of the same size as your projector, even though the mount point is a lot smaller surface area. The reason to use a larger surface area board is to spread the weight out a bit.

    For my projector (ECP 4101) I used a 3/4 MDF sheet and mounted it to the ceiling using 12, 4inch long screws. Its pretty happy up there.

    Roo
     
  10. James Bergeron

    James Bergeron Supporting Actor

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    Well actually I checked it's 3/4" MDF so I'm good to go! It's not as big as the projector but it's larger than the mounting bracket, I could have went wider and that may have been better, but I think it will be ok.

    Thanks.
     

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