On 12/24/2011 5:06 PM, Ignoramus22709 wrote:
On 2011-12-24, Howard wrote:

"Gunner wrote in message
...
On Sat, 24 Dec 2011 12:43:54 -0600, Ignoramus22709
wrote:

I made this forklift hook adaptor:

http://igor.chudov.com/tmp/Forklift-Hook.jpg

The horizontal cross bar is a rectangular tubing piece, 1/8" thick,
2x4 in cross section. ...
....
Thin wall tubing. No..its not going to hold 5k
....

I would not trust 1/8" to hold 5K, ...



Thanks guys. SOmeone else also told me the same thing. I think that
whatever I may be lifting, will be worth more than what a proper
adaptor costs, and also, the life and health is worth even more. I
will redo it, with some sadness.
....

Should have just gone and done some simple guess'ineering and gotten a
good idea it wasn't up to the task...

http://www.calculatoredge.com/civil%20engg%20calculator/beam.htm#hollow

For a 2-ft section of 1/8" tube, deflection for 5k load is roughly 1/4"
and a bending stress 80 kpsi (using yield of 29E6 psi). That's spooky
enough even w/ the crude approximation of real loading to be clearly
_a_bad_idea_ (tm).

--

On Sun, 25 Dec 2011 09:24:33 -0600, dpb wrote:

On 12/24/2011 5:06 PM, Ignoramus22709 wrote:
On 2011-12-24, Howard wrote:

"Gunner wrote in message
...
On Sat, 24 Dec 2011 12:43:54 -0600, Ignoramus22709
wrote:

I made this forklift hook adaptor:

http://igor.chudov.com/tmp/Forklift-Hook.jpg

The horizontal cross bar is a rectangular tubing piece, 1/8" thick,
2x4 in cross section. ...
...
Thin wall tubing. No..its not going to hold 5k
...

I would not trust 1/8" to hold 5K, ...



Thanks guys. SOmeone else also told me the same thing. I think that
whatever I may be lifting, will be worth more than what a proper
adaptor costs, and also, the life and health is worth even more. I
will redo it, with some sadness.
...

Should have just gone and done some simple guess'ineering and gotten a
good idea it wasn't up to the task...

http://www.calculatoredge.com/civil%20engg%20calculator/beam.htm#hollow

For a 2-ft section of 1/8" tube, deflection for 5k load is roughly 1/4"
and a bending stress 80 kpsi (using yield of 29E6 psi). That's spooky
enough even w/ the crude approximation of real loading to be clearly
_a_bad_idea_ (tm).

My belly told me there's something fishy about those numbers. Lacking
any information on the assumed loading and support conditions, that
calculator is worse than useless. It appears to be a calculation for a
cantilever beam.

The numbers for Iggy's setup yield a deflection of .016" and a stress
of 20 ksi at the center of the beam. In other words, it'd support the
5000#, but with an inadequate factor of safety for overhead lifting.
The stress *would* be acceptable in bridge and building construction.

Don't take this as an endorsement of the device -- I don't know all
the details of the construction, the soundness of the welds, or the
intended use.

--
Ned Simmons