"Pat" wrote in message
ups.com...
On Jul 2, 9:03 pm, "Eigenvector" wrote:
So I posted a little bit ago about hanging a punching bag from the
rafters.
I have the bag on a fixture mounted to 2 rafter beams (the rafters are
roof
trusses, 2x6's). The bag is a 110lb bag, hanging from an eyebolt . The
issue that I'm seeing is that when I punch the bag, the whole ceiling is
moving. I don't mean shifting off its mounts of course, but rather I can
see the ceiling drywall moving back and forth and rocking in tempo with
the
bag.

It's not like I'm Rocky Balboa or someone, but I'm a pretty strong guy
and
110lbs is a lot of weight. So I'm looking for some advice/options for my
concerns. My concerns being that I'm afraid that if the ceiling is
moving
enough for me to see, that means the whole structure is under way more
stress that it can take. But what to do about an object that weighs that
much but has to hang from 9 feet in the air. The rafters in my house are
at
exactly the right height.

Could I build up the rafters at the location where its suspended, add a
second 2x6, add a lot more cross bracing between the two rafters its hung
from, something like that. Admittedly I didn't do a lot of mod to the
hanging point, not knowing how it would respond I chose to take it slow
and
see if this was feasible or not.

Right now the eyebolt is hanging from 2 2x4's with a 1/2 plywood sheet on
top across 2 rafter beams. I believe MeatPlow offered that suggestion up
last time I posted this. Give a little more effort I could make a better
suspension jig, maybe 3 2x4's (hole for eyebolt in middle board), 1/2
plywood to tie them together on top.

I don't know, what do you all think?

I'll assume that you've already looked at all of the free-standing
supports and ruled them out for one reason or another.

I'm not quite sure, but it appears that you have mounted the bag to
the horizontal part of the joist and it has given you just the right
height. But by making a solid connection you are transferring the
energy from you bag to the joist. The joists aren't really pretty
flexible and that's what's moving.

You might want to consider hooking the bag to a rope and hooking the
rope to a rafter that is supporting the roofing. That will allow the
bag to have more movement (swinging) and get rid of a the jarring
aspect of the punch. It will get rid of the "hard" contact between
the bag and the support. Plus, the rafters are more stable.


/ \
/ | \
/ | \
/ | \
|
B
A
G


Good luck with it.


The more I look at this scenario the more I wonder if a stand would in fact
be a the best I could hope for.

My attic is an A frame truss, that is with 2x6's nailed to a ridgepole, and
a single 1x8 connecting each 2x6, plus a 2x6 ceiling beam. That's just not
an inherently stable configuration especially for jarring loads.

I'm gonna go ahead and try the rope trick, see what that will do for me but
I'm thinking my best hope is to get a stand - otherwise I might be faced
with a big leak in my roof from the stresses.

http://photos.imageevent.com/eigenve...e/P7070115.JPG
http://photos.imageevent.com/eigenve...e/P7070116.JPG