On 4/6/21 12:08 PM, Clare Snyder wrote:
On Tue, 06 Apr 2021 13:06:00 +0100, Richard Smith
wrote:

Clare Snyder writes:

On Sun, 4 Apr 2021 21:19:14 -0500, Robert Nichols
wrote:

On 4/4/21 4:52 PM, Clare Snyder wrote:
On Sun, 4 Apr 2021 09:36:53 -0500, Robert Nichols
wrote:

On 4/3/21 11:47 PM, Clare Snyder wrote:
On Sat, 3 Apr 2021 19:38:26 -0700 (PDT), Linda Iverson
wrote:

On Friday, August 2, 2019 at 6:18:04 AM UTC-7, Goncalves wrote:
replying to mjacobsen925, Goncalves wrote:
Really mjacobsen925, a forum is where one asks questions not where one gets
censored.
--
for full context, visit https://www.polytechforum.com/metalw...pe-639655-.htm

What if I just want to use black steel pipe as a curtain rod to hang heavy velvet drapes spanning a window greater than 12 feet long without the need for a center support? Ill anchor ends using flanges (nipples and elbows) screwed into solid wooden header above window. Seems like it should be more than strong enough for such a girly thing.
2 or 3 inch might work but not 3/4 or 1 inch unless you want them to
sag

The pipe, even 2 inch, will sag just from its own weight.
Sched 40 will sag - sched 80 MIGHT work in 2 inch but not with HEAVY
drapery

A 12 foot length of 2 inch Sched 80 steel pipe would weigh over 60 lbs.
That's quite some curtain rod!!
But it will support itself and some load over a 12 ft span. (about 1
1/2 times?? as much as sched 40.

Just did as bit of investigating and 1 1/4 inch sched 80 should be
adequate for a pretty heavy curtain - and weigh about 40 lb? - about
10 lb per meter) will sipport about 30 lb evenly didtributed with
about an inch of deflection.
Sched 40 will only handle around 20 lb with almost 1 1/2 inches of
deflection with a wight of ropughly 30 lb.

That's Euler-Bernoulli beam - very clear and exact. You can have the
load it can take and the deflection at that load to great accuracy.
If you set-up the load on the finished article, you'd find the
deflection matched to within a millimetre or something like that.
The end supports cannot be anything like rigid enough against rotation
to benefit the load capacity and stiffness against deflection.
You've got a "simple supported beam" ("double-supported beam").
A fair and reasonable conservative assumption would be to put the
entire weight of the curtain in the middle of the "curtain rail" when
doing the Euler-Bernoulli calculation for what tube to specify.
So that truly is the "simply supported centrally-loaded beam" case.

I do a lot of these calculations.
eg.
http://www.weldsmith.co.uk/tech/stru...lat_calcs.html


Rich Smith
Interesting liittle project - O like your reasoning and explanation -
particularly your "tap stick"
I've run into a lot of your "welders" who would make the thing so
heavy it could hardly support itself!!! (or they would fasten it to
the rig instead of the barge and it would be so heavy it would tip the
rig before it would bend - - -


Speaking of welders, how about making a truss? Those can be quite lightweight,
have a decorative design, and still be very rigid.

--
Bob Nichols AT comcast.net I am "RNichols42"