"Simon Lang" wrote in message
roupdirect.com...

Wanting legs for a winch base to pull concrete post bases from soil i have
seen a polish fellow make one, he was using square steel tube about 1-1/4"
tube about,

thanks to trump and covid none is locally available,
i pulled some 3/4 inch gas line from my house was wondering if i could use
this instead of square tube max stress according to the winch would be 1200
lbs i suspect it to be about 500 to 700 lbs

--
for full context, visit
https://www.polytechforum.com/metalw...pe-651220-.htm

---------------------------------

Possibly, if you design the support correctly.

https://amesweb.info/Beam/Column-Buc...alculator.aspx

Load capacity increases rapidly with diameter, doubling or more with each
step up in pipe size. I use tripods of 2" pipe, EMT and chain link fence
posts to pull stumps and lift logs and boulders weighing much more than your
estimated load, after calculating their column strength, proof testing with
a load cell and applying a safety factor.

However I'm not a structural engineer and don't know how to calculate the
loss from the off-center loading component of my method of connecting the
legs and hoist flexibly at the top so I won't describe it or mention how
much weight I've lifted.

The problem can be solved with hardware store material if you figure out
how. The keys are maximizing the second moment of area and not wasting it
with bending loads on the columns, or threaded pipe joints and fittings.

Smaller diameter tubing has failed the proof test and the 2" stuff can
buckle if accidentally hit on the side. I've retired several 2" legs for
damage.

An electric winch adds a considerable jolt to the static load as it pulls
tight, though it lets you stand further away from the danger zone. I prefer
a manual lever chain hoist or a chain fall that gives feedback of the legs
buckling or sinking into the ground or other developing problems.