Dale, Very good point, if this is a swing for really "swinging", I can imagine letting a foot down just too far as you come forward and getting it caught on the edge. Could propell one's little blind face right down on the concrete porch.
If this is just a lovers swing, it might not be so bad, but any time a part of the old bod is being propelled towards a hard edge, it's a worry. Tom Fowle On Wed, Sep 09, 2009 at 04:56:02PM -0400, Dale Leavens wrote: > All you say is of course true Dan and with a lever ratio like that I think it > would be really hard to keep bolts secure in the concrete. > > I have misgivings though about having a swing moving out over the edge of a > concrete platform. Sounds to me like a good way to get a leg broken or > someone to get hit as the swing glides backward out over the open space. > > > ----- Original Message ----- > From: Dan Rossi > To: blindhandyman@yahoogroups.com > Sent: Wednesday, September 09, 2009 9:38 AM > Subject: Re: [BlindHandyMan] Calculating load capability > > > Nancy, > > I agree that you probably don't have to worry about the posts snapping off > but remember that as the swing moves forward, the uprights are attempting > to pivot around the point where they cross the floor of the porch, meaning > that the bottoms of the posts are pulling away from the wall of the porch. > Not only that, but since the floor of the porch is the fulcrum, you have a > six foot lever arm above, and maybe a ten inch lever arm below, so the > force at the top of the uprights, as the swing moves forward, is > multiplied by about 7 times and that is a force attempting to pull the > bolts out of the porch wall. > > I would think that sinking the posts into concrete a couple of feet down > would go a long way to helping the system be more structurally stable. > > We've just had a discussion on the issues of burying posts or not, so you > can make your own decision on that point, but I think that it might be > prudent in this case. > > As far as chain strength, the guys at any big box store should be able to > tell you what the relative strengths are of the various gauges of chain. > I don't have any real knowledge of that. > > -- > Blue skies. > Dan Rossi > Carnegie Mellon University. > E-Mail: d...@andrew.cmu.edu > Tel: (412) 268-9081 > > > > > [Non-text portions of this message have been removed] >
