Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old January 19th 20, 05:18 AM posted to rec.crafts.metalworking
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Default U channel and squire tube which one is strong

8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube

--
for full context, visit https://www.polytechforum.com/metalw...ng-649641-.htm



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Old January 19th 20, 11:47 AM posted to rec.crafts.metalworking
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Default U channel and squire tube which one is strong

Jahan writes:

8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube

--
for full context, visit https://www.polytechforum.com/metalw...ng-649641-.htm


That's a fairly complex engineering question (??)

Apart from in pure tension, the load limit is usually about when the
section will buckle - go unstable - or exceed elastic bending
(smallish) and plastic bend by large amounts to collapse.

Normally, when the service is not pure tension, closed sections -
SHS's - Structural Hollow Section - are much stiffer for the same
amount of material and will give a much higher load bearing.

The technical breakthrough of being able to economically manufacture
large amounts of Structural Hollow Section from good-specification
steel has been a transformation.
Other advantages with SHS's are eliminating rust-traps, with
hermetically-sealed internal volumes (no corrosion) and smooth
external sections advantaging paint systems to give good protection
against corrosion for long low-maintenance service.
Hence the return (?) of truss bridges.

Complex matters.

You'll be wanting to study Second Moment of Area and the beam and
column calculations / equations.
The Euler column and the Euler-Bernoulli beam (both derived around the
1750's - about 250 years ago) which serve well for most applications
of beams and columns.

Regards,
Rich Smith
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Old January 19th 20, 05:46 PM posted to rec.crafts.metalworking
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Default U channel and squire tube which one is strong

"Jahan" wrote in
message
oupdirect.com...
8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube
--
for full context, visit
https://www.polytechforum.com/metalw...ng-649641-.htm

There are many web sites like this with strength calculators and
material properties.
https://www.roguefab.com/tube-calculator/

You need some familiarity with the mathematics and vocabulary of
"Statics" to make good use of them.
https://en.wikipedia.org/wiki/Statics



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Old January 19th 20, 10:23 PM posted to rec.crafts.metalworking
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Default U channel and squire tube which one is strong

"Richard Smith" wrote in message
...
Jahan writes:

8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube

....
You'll be wanting to study Second Moment of Area and the beam and
column calculations / equations.
The Euler column and the Euler-Bernoulli beam (both derived around
the
1750's - about 250 years ago) which serve well for most applications
of beams and columns.

Regards,
Rich Smith


When I built a log splitter, sawmill and a hydraulic bucket loader for
my tractor I welded every joint that wouldn't have to be taken apart
to store or modify them. However structural steel design manuals say
to avoid field welding whenever possible, due to high cost. They are
more neutral about shop welding versus bolting. Why would field
welding be prohibitably expensive? Heavy construction equipment is
almost entirely welded.


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Old January 20th 20, 10:50 PM posted to rec.crafts.metalworking
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Posts: 31
Default U channel and squire tube which one is strong

"Jim Wilkins" writes:

"Richard Smith" wrote in message
...
Jahan writes:

8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube

....
You'll be wanting to study Second Moment of Area and the beam and
column calculations / equations.
The Euler column and the Euler-Bernoulli beam (both derived around
the
1750's - about 250 years ago) which serve well for most applications
of beams and columns.

Regards,
Rich Smith


When I built a log splitter, sawmill and a hydraulic bucket loader for
my tractor I welded every joint that wouldn't have to be taken apart
to store or modify them. However structural steel design manuals say
to avoid field welding whenever possible, due to high cost. They are
more neutral about shop welding versus bolting. Why would field
welding be prohibitably expensive? Heavy construction equipment is
almost entirely welded.


Big difference between commercial and hobby, in all practical / real
senses.

That contention, "field welding expensive", would be true for typical
commercial cases.
Commercially, you use MIG (GMAW) in a workshop, and SMAW on-site

* in a well-set-up fab-shop MIG (GMAW) is vastly faster than stick
(SMAW) applied in the same situation

* they'd be talking about bolted steel connections for buildings -
"rattle-gun" (impact wrench) a few bolts, rather than weld (SMAW)
(noting that at the ends of beams, where the bolts are, you only
have a small shear force, with all the serious big beam bending
stresses far away in the mid-length of the beam)

Hence, commercially, due to processes used and the majority
application, the statement is true.

In a hobby workshop, at best you still have a single-phase electric
power and you cannot pull those 15kW from the mains which makes
fabshop MIG so productive. Most MIG's are transformer and something
like 50% efficient, whereas many SMAW sets now are inverters and
high-90's percent efficient - so those 3.12kW (British 240V 13A max)
give almost twice the bang-per-buck and even up the productivity. No
loss of productivity outdoors with stick, which is one of the few
processes which is in reality rather tolerant of wind and rain.
Then you are going to have much more trouble making bolted joints that
in a well-set-up commercial shop, with all your marking tools,
benches, ironworker for punching holes, etc, etc, etc.

In summary - it's no wonder you see a different picture where for your
home fabs. welding is vastly easier and quicker.

It all makes complete sense - be assured of that.

Regards,
Rich Smith


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Old January 21st 20, 01:16 AM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Jun 2011
Posts: 5,543
Default U channel and squire tube which one is strong

"Richard Smith" wrote in message
...
"Jim Wilkins" writes:

"Richard Smith" wrote in message
...
Jahan writes:

8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube

....
You'll be wanting to study Second Moment of Area and the beam and
column calculations / equations.
The Euler column and the Euler-Bernoulli beam (both derived around
the
1750's - about 250 years ago) which serve well for most
applications
of beams and columns.

Regards,
Rich Smith


When I built a log splitter, sawmill and a hydraulic bucket loader
for
my tractor I welded every joint that wouldn't have to be taken
apart
to store or modify them. However structural steel design manuals
say
to avoid field welding whenever possible, due to high cost. They
are
more neutral about shop welding versus bolting. Why would field
welding be prohibitably expensive? Heavy construction equipment is
almost entirely welded.


Big difference between commercial and hobby, in all practical / real
senses.

That contention, "field welding expensive", would be true for
typical
commercial cases.
Commercially, you use MIG (GMAW) in a workshop, and SMAW on-site

* in a well-set-up fab-shop MIG (GMAW) is vastly faster than stick
(SMAW) applied in the same situation

* they'd be talking about bolted steel connections for buildings -
"rattle-gun" (impact wrench) a few bolts, rather than weld (SMAW)
(noting that at the ends of beams, where the bolts are, you only
have a small shear force, with all the serious big beam bending
stresses far away in the mid-length of the beam)

Hence, commercially, due to processes used and the majority
application, the statement is true.

In a hobby workshop, at best you still have a single-phase electric
power and you cannot pull those 15kW from the mains which makes
fabshop MIG so productive. Most MIG's are transformer and something
like 50% efficient, whereas many SMAW sets now are inverters and
high-90's percent efficient - so those 3.12kW (British 240V 13A max)
give almost twice the bang-per-buck and even up the productivity.
No
loss of productivity outdoors with stick, which is one of the few
processes which is in reality rather tolerant of wind and rain.
Then you are going to have much more trouble making bolted joints
that
in a well-set-up commercial shop, with all your marking tools,
benches, ironworker for punching holes, etc, etc, etc.

In summary - it's no wonder you see a different picture where for
your
home fabs. welding is vastly easier and quicker.

It all makes complete sense - be assured of that.

Regards,
Rich Smith


So MIG indoors but stick outside. I though flux-core could stand a
breeze too. Does the time the crane spends holding the beam in
position figure in?

For reference, I do have a milling machine to locate and drill gusset
plate and beam end hole patterns, a 1 ton crane to lift steel, and my
welding and plasma cutting circuit is 240V, 100A which is half the
panel's capacity. I'm equipped to make and test prototype robotic and
aerospace components when I'm not sure what I want without seeing (and
modifying) the mental concept. The boss told me my parts looked like
they came from a Norden bombsight

The sawmill etc were retirement projects.





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Old January 21st 20, 02:12 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Jul 2006
Posts: 2,443
Default U channel and squire tube which one is strong

On 1/18/2020 11:18 PM, Jahan wrote:
8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube


How is this not a "duh"? The U channel is basically 1/2 the tube (3.2"
x 1.2").
  #8   Report Post  
Old January 21st 20, 08:31 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Apr 2016
Posts: 31
Default U channel and squire tube which one is strong

"Jim Wilkins" writes:

"Richard Smith" wrote in message
...
"Jim Wilkins" writes:

"Richard Smith" wrote in message
...
Jahan writes:

8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube

....
You'll be wanting to study Second Moment of Area and the beam and
column calculations / equations.
The Euler column and the Euler-Bernoulli beam (both derived around
the
1750's - about 250 years ago) which serve well for most
applications
of beams and columns.

Regards,
Rich Smith

When I built a log splitter, sawmill and a hydraulic bucket loader
for
my tractor I welded every joint that wouldn't have to be taken
apart
to store or modify them. However structural steel design manuals
say
to avoid field welding whenever possible, due to high cost. They
are
more neutral about shop welding versus bolting. Why would field
welding be prohibitably expensive? Heavy construction equipment is
almost entirely welded.


Big difference between commercial and hobby, in all practical / real
senses.

That contention, "field welding expensive", would be true for
typical
commercial cases.
Commercially, you use MIG (GMAW) in a workshop, and SMAW on-site

* in a well-set-up fab-shop MIG (GMAW) is vastly faster than stick
(SMAW) applied in the same situation

* they'd be talking about bolted steel connections for buildings -
"rattle-gun" (impact wrench) a few bolts, rather than weld (SMAW)
(noting that at the ends of beams, where the bolts are, you only
have a small shear force, with all the serious big beam bending
stresses far away in the mid-length of the beam)

Hence, commercially, due to processes used and the majority
application, the statement is true.

In a hobby workshop, at best you still have a single-phase electric
power and you cannot pull those 15kW from the mains which makes
fabshop MIG so productive. Most MIG's are transformer and something
like 50% efficient, whereas many SMAW sets now are inverters and
high-90's percent efficient - so those 3.12kW (British 240V 13A max)
give almost twice the bang-per-buck and even up the productivity.
No
loss of productivity outdoors with stick, which is one of the few
processes which is in reality rather tolerant of wind and rain.
Then you are going to have much more trouble making bolted joints
that
in a well-set-up commercial shop, with all your marking tools,
benches, ironworker for punching holes, etc, etc, etc.

In summary - it's no wonder you see a different picture where for
your
home fabs. welding is vastly easier and quicker.

It all makes complete sense - be assured of that.

Regards,
Rich Smith


So MIG indoors but stick outside. I though flux-core could stand a
breeze too. Does the time the crane spends holding the beam in
position figure in?

For reference, I do have a milling machine to locate and drill gusset
plate and beam end hole patterns, a 1 ton crane to lift steel, and my
welding and plasma cutting circuit is 240V, 100A which is half the
panel's capacity. I'm equipped to make and test prototype robotic and
aerospace components when I'm not sure what I want without seeing (and
modifying) the mental concept. The boss told me my parts looked like
they came from a Norden bombsight

The sawmill etc were retirement projects.


That's a lot of experience!
Need to only say what I can reasonably comment.

Gassless FCAW (Flux-Cored Arc Welding) can be used outdoors, yes.
Never met it - seen it in a welder testing ("Coding") centre once but
not watched what its like, running.

With shielding gas FCAW - not outside.

Crane time - yes, I would reckon - all times and use of resources add.

I think I have said as much as my experience permits.

Best wishes,
Rich S
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Old January 21st 20, 10:00 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Oct 2012
Posts: 3,095
Default U channel and squire tube which one is strong

On 1/21/2020 1:31 PM, Richard Smith wrote:
"Jim Wilkins" writes:

"Richard Smith" wrote in message
...
"Jim Wilkins" writes:

"Richard Smith" wrote in message
...
Jahan writes:

8 cm wide by 3 cm U Channel and 3 x 3 inch x 2 mm tube

....
You'll be wanting to study Second Moment of Area and the beam and
column calculations / equations.
The Euler column and the Euler-Bernoulli beam (both derived around
the
1750's - about 250 years ago) which serve well for most
applications
of beams and columns.

Regards,
Rich Smith
When I built a log splitter, sawmill and a hydraulic bucket loader
for
my tractor I welded every joint that wouldn't have to be taken
apart
to store or modify them. However structural steel design manuals
say
to avoid field welding whenever possible, due to high cost. They
are
more neutral about shop welding versus bolting. Why would field
welding be prohibitably expensive? Heavy construction equipment is
almost entirely welded.
Big difference between commercial and hobby, in all practical / real
senses.

That contention, "field welding expensive", would be true for
typical
commercial cases.
Commercially, you use MIG (GMAW) in a workshop, and SMAW on-site

* in a well-set-up fab-shop MIG (GMAW) is vastly faster than stick
(SMAW) applied in the same situation

* they'd be talking about bolted steel connections for buildings -
"rattle-gun" (impact wrench) a few bolts, rather than weld (SMAW)
(noting that at the ends of beams, where the bolts are, you only
have a small shear force, with all the serious big beam bending
stresses far away in the mid-length of the beam)

Hence, commercially, due to processes used and the majority
application, the statement is true.

In a hobby workshop, at best you still have a single-phase electric
power and you cannot pull those 15kW from the mains which makes
fabshop MIG so productive. Most MIG's are transformer and something
like 50% efficient, whereas many SMAW sets now are inverters and
high-90's percent efficient - so those 3.12kW (British 240V 13A max)
give almost twice the bang-per-buck and even up the productivity.
No
loss of productivity outdoors with stick, which is one of the few
processes which is in reality rather tolerant of wind and rain.
Then you are going to have much more trouble making bolted joints
that
in a well-set-up commercial shop, with all your marking tools,
benches, ironworker for punching holes, etc, etc, etc.

In summary - it's no wonder you see a different picture where for
your
home fabs. welding is vastly easier and quicker.

It all makes complete sense - be assured of that.

Regards,
Rich Smith

So MIG indoors but stick outside. I though flux-core could stand a
breeze too. Does the time the crane spends holding the beam in
position figure in?

For reference, I do have a milling machine to locate and drill gusset
plate and beam end hole patterns, a 1 ton crane to lift steel, and my
welding and plasma cutting circuit is 240V, 100A which is half the
panel's capacity. I'm equipped to make and test prototype robotic and
aerospace components when I'm not sure what I want without seeing (and
modifying) the mental concept. The boss told me my parts looked like
they came from a Norden bombsight

The sawmill etc were retirement projects.

That's a lot of experience!
Need to only say what I can reasonably comment.

Gassless FCAW (Flux-Cored Arc Welding) can be used outdoors, yes.
Never met it - seen it in a welder testing ("Coding") centre once but
not watched what its like, running.


* I use it all the time ... it runs just like solid wire with gas , but
works well outdoors as long as the wind isn't too bad . It does burn
hotter than solid wire , probably because the flux consumes the oxygen
in the weld zone (I think ...) . It does spatter more , and you do have
a little flux to clean off the weld , but the flux is usually pretty
soft and easy to remove - the spatter is harder to get off . The main
reason I use it is because it does burn hotter and I've been doing
repairs to thicker sections , right at the limits of my Lincoln 110V
Weldpak unit . If I need more power , I use either the 225A (AC only)
Tombstone or the TIG (AC/DC 250 amps) welder in stick mode .



With shielding gas FCAW - not outside.


* Are you referring to dual-shield or solid wire ?



Crane time - yes, I would reckon - all times and use of resources add.

I think I have said as much as my experience permits.

Best wishes,
Rich S



--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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Old January 21st 20, 10:51 PM posted to rec.crafts.metalworking
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Posts: 5,543
Default U channel and squire tube which one is strong

"Richard Smith" wrote in message
...
"Jim Wilkins" writes:
....
Need to only say what I can reasonably comment.

Gassless FCAW (Flux-Cored Arc Welding) can be used outdoors, yes.
Never met it - seen it in a welder testing ("Coding") centre once
but
not watched what its like, running.

With shielding gas FCAW - not outside.

Crane time - yes, I would reckon - all times and use of resources
add.

I think I have said as much as my experience permits.

Best wishes,
Rich S


Thanks. I've acquired a heap of galvanized tubing that might become an
upgrade to my 50' antenna mast, and was wondering if I'd missed a
reason why welding on a structure was discouraged, since it's how
ships are built.




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