|
Posted by on November 2, 2007, 2:41 pm
> On Nov 2, 2:40 am, alvinamo...@notmail.com wrote:
>
>
>
>
>
> > When I installed my (used) wooden garage door some years ago, the door
> > was made for an 8 foot high wall, thus the door is about 7 feet. My
> > garage walls are 9 feet tall. But I needed to save some money and had
> > that door, and really did not need the extra height. The only problem
> > is that the rails were 2 feet lower than the ceiling rafters. I just
> > installed a couple 2 foot 2x4's. Shortly after, one of them split
> > from the spring pressure, so I added another 2x4 (doubled it). That
> > worked fine but I soon had to add some angle braces because the 2x4's
> > were pulling loose from the rafters (by the nails). A year later one
> > of them almost pulled off the rafter, so I added carriage bolts.
> > After that I was fine until a couple months ago when one of the spring
> > cables broke. The spring launched, completely destroying the entire
> > (double) 2x4 and brace, and the spring ripped apart some shelves in
> > the rear of the garage in the process.
>
> > I am finally getting around to fixing this. I got new cables and also
> > got a set of safety cables so if it breaks again, no one gets hurt.
> > However, I am wondering if I should use some of that angle steel
> > rather than 2x4's this time. It's made for that purpose. But it's
> > not the thickest steel, and while it might work for a one foot or less
> > drop, will it support a 2 foot drop without buckling? On the other
> > hand, I could use some thick angle iron for the main support and just
> > use that thinner garage door steel for the braces.
>
> > I know I can make something work, but was wondering if anyone else had
> > used that angle stock made for garage doors and if it was strong
> > enough for my needs.
>
> > Thanks
>
> I'm a little confused here........but seems like you're describing a
> sectional door installation but how did the "spring pressure" cause
> the 2x4 failure?
>
He has a sectional door with extension springs. One of them broke
while extended and it sounds like it was the end closest to the door
that broke. The spring which was under tension, then goes flying
back towards the support hanging from the ceiling and hit it with
great force. And of course the longer the suspension from the
ceiling the more leverage it has to rip the support out.
I had the cable snap recently on one of my springs. It didn't rip
out the support from the ceiling, but it did jerk it backward and the
track on that side with it enough to rip the 2X4 that the door
vertical door track was attached to from the door opening. Net
result was the door was pulled back about an inch on that side. I
had to take the whole door apart to remove the rail and reattach the
2X4. They should have used more nails and maybe it wouldn't have
come loose. But the mechanism is the same as what the OP is
describing.
All the mistakes that this guy has made, he's lucky he hasn't killed
someone by now.
> Or is this a slab door with guide tracks & a suspended pivot point???
> If so ignore the sectional door comments.
>
> If its a slab door & suspended pivot....your mounting location needs
> to be nearly as strong as the garage ceiling diaphragm. So you'll
> need to make a relatively strong & stiff "drop ceiling"".
>
> like two narrow runs of drop ceiling about 18" wide (at the ceiling)
> tapering to 6" wide at the track, that way you can take advantage of
> the plywood 24" half width & get twice as many braces from a sheet.
> Skin the braces (vertical & angled surfaces) and you've got a very
> strong & stiff mount for all the door hardware.
>
> Sectional door relative comments:
>
> I've seen lots of sectional door installations (& have one) where the
> horizontal portions of the roller guide tracks (rails) are a ways down
> from the garage ceiling. My installation uses that thin angle
> material with all the holes in it, not the strongest stuff but no
> problems so far (10years).
>
> However, not 2 feet. Two feet seems like a lot but you should be
> able to support & brace it with fairly thin angle material. I would
> suggest supporting & bracing the rails at three locations per
> horizontal run. Use a vertical angle member at each location AND a
> 45 deg angled brace as well.
>
> The loads on each support & brace will be pretty low....just make sure
> that everything is lined up straight & square so the door is "happy"
> during its travel.
>
> The vertical supports can be lighter material, the braces need to be
> thicker because the supports are in tension (more stable) but the
> braces are in compression or tension depending in the loading demands.
>
> No need for massive angle irons.....a possible substitute for angle
> material would be 1/2" EMT which would be less likely to buckle but
> perhaps more problematic to deal with connections.
>
> Just make sure you can adjust everything before final attachment so
> they're tight & don't tweak the rails out of true.
>
> Wooden members (esp 2x4's) when short & nailed tend not to work too
> well...."grain effects" come into play causing splits.
>
> If wood is easier for you to work with, you could make up some angle
> brackets from 3/4" plywood; glued & screwed or pin nailed. Kinda big
> & kludgey but really stiff.
>
> cheers
> Bob- Hide quoted text -
>
> - Show quoted text -
|