In article rs.com,
buck wrote:
OK here's one for you mechanical engineers out there........... I want to
screw two (2) screw eyebolts into an overhead 2x4 rafter. Then I will
attach a 3' long chain to each one so that they hang down. Assuming that
the wood of the rafter is excellent and structurally sound as well as any
other hardware, such as the chain ...... "Would these two screw eyebolts
hold up to 400 pounds (share 200 pounds each)? I have no real good idea of
shear factor for this type of fastener........ ie. Would the screw break
before the wood?????

The eyebolts that would be used are 3/8" diameter and 3 1/2" - 4" long. The
eyebolts would be just standard Home Depot mild steel with galvanized plate
plate I suppose. I am thinking that these two bolts would equally share the
load and probably be fine but......... The weight of 400 pounds might strip
them out of the 2x4s....... Is this likely or would the threads be strong
enough ??
Not looking for any promises.... just some good swags. And yes, I am
intending to hang from this but I weigh a little over 200 pounds.... safety
factor you know..... :~)

Thanks for any help!




I am guessing you mean a joist and not a rafter? And you are talking
about an "eyebolt" that has a thread like a lag bolt, correct? If so,
I have always called these "screw eyes" and use the term "eyebolt" for
a bolt with machine threads that goes in a through-hole, with
a nut on the end. Maybe someone here can verify what the correct
nomenclature is.

At any rate, if the wood is sound and the pilot hole sized properly
to the eyebolt/screw eye, it should able to support 200lbs dead load
without pulling the threads out of the wood.

Some thoughts and concerns: You mention that you will be "hanging"
from the eyebolts. That's probably OK but if you are "swinging"
from them, maybe not, especially in soft wood. No way for instance,
that I'd hang a kids swing from a screw eye.
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Larry Wasserman Baltimore, Maryland