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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  #11   Report Post  
Old January 22nd 20, 09:52 PM posted to rec.crafts.metalworking
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Default U channel and squire tube which one is strong

"Jim Wilkins" writes:

....


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.


* you'd burn the galv away around the weld - and the weld never has
any galv (spray with zinc-based paint - which will need periodically
reapiring / re-applying)

* you are not supposed to weld over galv. Zink toxicity & disturbs
arc (arc goes a lilac colour) & could affect weld strength and
fusion

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Old January 22nd 20, 11:42 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:

....


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.


* you'd burn the galv away around the weld - and the weld never has
any galv (spray with zinc-based paint - which will need
periodically
reapiring / re-applying)

* you are not supposed to weld over galv. Zink toxicity & disturbs
arc (arc goes a lilac colour) & could affect weld strength and
fusion


We went over this a while ago, and I asked you what you paint on the
weld because the brush-on zinc-rich paint I have lets rust bleed
through after a year or three, even though I sandblasted the area
clean first. I then sprayed on waxy LPS-3 which kept the rust from
expanding, but it seems to need some existing rust to soak into or it
washes off.

The goop that does last outdoors is Ox-Gard, for aluminium electrical
connections. The element and feed connections on my antennas remain at
a few milliOhms for many years after scrubbing them and quickly
applying it. I measure the resistance with a voltmeter while 1.00A
flows through the joint, 1mV = 1 milliOhm. I had to drill out the
rivets and install aluminium screws and nuts.

Our digital TV reception is much better than the old analog, and TVs
aren't taxed in the USA, however almost everyone prefers to pay
$150/month and up for cable. Antenna reception is pretty much a
do-it-yourself project with no repairmen to call. This British digital
receiver with the spectrum analyzer program is a great aid in aiming
the antenna to minimize multipath.
https://www.sdrplay.com/rsp1a/


  #13   Report Post  
Old January 23rd 20, 12:31 AM posted to rec.crafts.metalworking
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Posts: 275
Default U channel and squire tube which one is strong

On 22/01/2020 22:42, Jim Wilkins wrote:
"Richard Smith" wrote in message
...
"Jim Wilkins" writes:

....
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.

* you'd burn the galv away around the weld - and the weld never has
any galv (spray with zinc-based paint - which will need
periodically
reapiring / re-applying)

* you are not supposed to weld over galv. Zink toxicity & disturbs
arc (arc goes a lilac colour) & could affect weld strength and
fusion

We went over this a while ago, and I asked you what you paint on the
weld because the brush-on zinc-rich paint I have lets rust bleed
through after a year or three, even though I sandblasted the area
clean first. I then sprayed on waxy LPS-3 which kept the rust from
expanding, but it seems to need some existing rust to soak into or it
washes off.

The goop that does last outdoors is Ox-Gard, for aluminium electrical
connections. The element and feed connections on my antennas remain at
a few milliOhms for many years after scrubbing them and quickly
applying it. I measure the resistance with a voltmeter while 1.00A
flows through the joint, 1mV = 1 milliOhm. I had to drill out the
rivets and install aluminium screws and nuts.

Our digital TV reception is much better than the old analog, and TVs
aren't taxed in the USA, however almost everyone prefers to pay
$150/month and up for cable. Antenna reception is pretty much a
do-it-yourself project with no repairmen to call. This British digital
receiver with the spectrum analyzer program is a great aid in aiming
the antenna to minimize multipath.
https://www.sdrplay.com/rsp1a/


I used some Rustoleum aerosol cold zinc spray on some outdoor galvanised
steel I had to weld and after cleaning and applying 5 years on no sign
of any rust.

  #14   Report Post  
Old January 23rd 20, 01:56 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Feb 2010
Posts: 10,373
Default U channel and squire tube which one is strong

On Mon, 20 Jan 2020 21:50:09 +0000, Richard Smith
wrote:

"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


Well stated!

As noted.. commercial shops tend to punch holes rather than machine
them. Its faster by far..IF you have the machinery..than drilling.

One of the biggest issues..is the difficulty transporting a gizmo that
has been welded together ..or the ease of putting a bunch of pieces in
a flat carton and shipping it off the client, to be bolted together on
site.

A perfect example is this 11 foot (on the diagonal) part I had to fab
for a project. I had to transport it on a flat bed truck, tilted on
an angle. If I had to make them for resale..Id have built it as a bolt
together out of parts to fit bundled together.

https://photos.app.goo.gl/H2t1cd5TMVzr9SDR9

Gunner
__

"Journalists are extremely rare and shouldn’t be harmed, but propagandists are everywhere and should be hunted for sport"

Yeah..with no bag limit.



  #15   Report Post  
Old January 23rd 20, 01:59 PM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Feb 2010
Posts: 10,373
Default U channel and squire tube which one is strong

On Wed, 22 Jan 2020 20:52:07 +0000, Richard Smith
wrote:

"Jim Wilkins" writes:

....


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.


* you'd burn the galv away around the weld - and the weld never has
any galv (spray with zinc-based paint - which will need periodically
reapiring / re-applying)

* you are not supposed to weld over galv. Zink toxicity & disturbs
arc (arc goes a lilac colour) & could affect weld strength and
fusion


Cleaning off the galv is tough..and then reapplying it is a pain in
the ass..but for oneoffs..its more than doable for a hobbiest.

__

"Journalists are extremely rare and shouldn’t be harmed, but propagandists are everywhere and should be hunted for sport"

Yeah..with no bag limit.





  #16   Report Post  
Old January 23rd 20, 02:00 PM posted to rec.crafts.metalworking
external usenet poster
 
First recorded activity by DIYBanter: Feb 2010
Posts: 10,373
Default U channel and squire tube which one is strong

On Wed, 22 Jan 2020 23:31:23 +0000, David Billington
wrote:

On 22/01/2020 22:42, Jim Wilkins wrote:
"Richard Smith" wrote in message
...
"Jim Wilkins" writes:

....
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.
* you'd burn the galv away around the weld - and the weld never has
any galv (spray with zinc-based paint - which will need
periodically
reapiring / re-applying)

* you are not supposed to weld over galv. Zink toxicity & disturbs
arc (arc goes a lilac colour) & could affect weld strength and
fusion

We went over this a while ago, and I asked you what you paint on the
weld because the brush-on zinc-rich paint I have lets rust bleed
through after a year or three, even though I sandblasted the area
clean first. I then sprayed on waxy LPS-3 which kept the rust from
expanding, but it seems to need some existing rust to soak into or it
washes off.

The goop that does last outdoors is Ox-Gard, for aluminium electrical
connections. The element and feed connections on my antennas remain at
a few milliOhms for many years after scrubbing them and quickly
applying it. I measure the resistance with a voltmeter while 1.00A
flows through the joint, 1mV = 1 milliOhm. I had to drill out the
rivets and install aluminium screws and nuts.

Our digital TV reception is much better than the old analog, and TVs
aren't taxed in the USA, however almost everyone prefers to pay
$150/month and up for cable. Antenna reception is pretty much a
do-it-yourself project with no repairmen to call. This British digital
receiver with the spectrum analyzer program is a great aid in aiming
the antenna to minimize multipath.
https://www.sdrplay.com/rsp1a/


I used some Rustoleum aerosol cold zinc spray on some outdoor galvanised
steel I had to weld and after cleaning and applying 5 years on no sign
of any rust.


Thats good stuff btw.

It also depends on the climate of the area its to be used in. Where I
live in the desert...it rusts so slowly that its almost not worth
reapplying the galv. In Florida..its manditory.

__

"Journalists are extremely rare and shouldn’t be harmed, but propagandists are everywhere and should be hunted for sport"

Yeah..with no bag limit.



  #17   Report Post  
Old January 24th 20, 10:26 PM posted to rec.crafts.metalworking
external usenet poster
 
First recorded activity by DIYBanter: Apr 2016
Posts: 29
Default U channel and squire tube which one is strong

Gunner Asch writes:

On Mon, 20 Jan 2020 21:50:09 +0000, Richard Smith
wrote:

"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


Well stated!

As noted.. commercial shops tend to punch holes rather than machine
them. Its faster by far..IF you have the machinery..than drilling.

One of the biggest issues..is the difficulty transporting a gizmo that
has been welded together ..or the ease of putting a bunch of pieces in
a flat carton and shipping it off the client, to be bolted together on
site.

A perfect example is this 11 foot (on the diagonal) part I had to fab
for a project. I had to transport it on a flat bed truck, tilted on
an angle. If I had to make them for resale..Id have built it as a bolt
together out of parts to fit bundled together.

https://photos.app.goo.gl/H2t1cd5TMVzr9SDR9

Gunner


Laser'ing is really the great thing - assume it's gone even more that
way in the States?
Avoid having to debur punched holes, flatten plates again, etc.
Holes all there laser'ed.
Get a pallet-load of plates with identities "etched" with defocussed
laser beam.

I've made big-ish platforms with bolted connections not needed for any
structural reason, solely so the broken-apart structure will fit on a
3~1/2 tonne flatbed truck.

Regards,
Rich Smith
  #18   Report Post  
Old January 25th 20, 12:01 AM posted to rec.crafts.metalworking
external usenet poster
 
First recorded activity by DIYBanter: Feb 2010
Posts: 10,373
Default U channel and squire tube which one is strong

On Fri, 24 Jan 2020 21:26:15 +0000, Richard Smith
wrote:

Gunner Asch writes:

On Mon, 20 Jan 2020 21:50:09 +0000, Richard Smith
wrote:

"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


Well stated!

As noted.. commercial shops tend to punch holes rather than machine
them. Its faster by far..IF you have the machinery..than drilling.

One of the biggest issues..is the difficulty transporting a gizmo that
has been welded together ..or the ease of putting a bunch of pieces in
a flat carton and shipping it off the client, to be bolted together on
site.

A perfect example is this 11 foot (on the diagonal) part I had to fab
for a project. I had to transport it on a flat bed truck, tilted on
an angle. If I had to make them for resale..Id have built it as a bolt
together out of parts to fit bundled together.

https://photos.app.goo.gl/H2t1cd5TMVzr9SDR9

Gunner


Laser'ing is really the great thing - assume it's gone even more that
way in the States?


Laser cutting is still expensive, so most heavy large items that can
be toleranced with a tape measure are still punched or torch cut.
Laser cutting (except for aerospace and medical) tends to still be
part and parcel "small parts with lots of details"...much like large
EDM. EDM has lost so much ground in the past 20 yrs its actually
becoming rather rare to find in shops. If you need something
EDM'd...send it out is the trend.
CNC plasma cutting does the yoemans share of this sort of work. Its
about the cheapest bulk cutting method out there. Getting to be a
fraction of torch cutting if you have details. You simply have to
hire a minimum wage kid to run a big angle grinder to clear off the
slag and any ridges. What wetback...er..undocumented aliens are
for..least here in Californiastan.

Avoid having to debur punched holes, flatten plates again, etc.
Holes all there laser'ed.
Get a pallet-load of plates with identities "etched" with defocussed
laser beam.


Ayup..that is one of the handy things you can do with lasers. Or water
jets. Water jetting is spendy..but much less spendy than laser
cutting these days. Its not so much the cost per hour of the two..but
the inititial cost of the machine and service costs. Water jet has
become much cheaper over the past 15 yrs. But laser is catching
up..slowly.


I've made big-ish platforms with bolted connections not needed for any
structural reason, solely so the broken-apart structure will fit on a
3~1/2 tonne flatbed truck.

Regards,
Rich Smith


Ayup. There is a lot of stuff done like an erector set. Comes in a
box..and you put it together onsite. Some of it is actually well
engineered too!

Gunner
__

"Journalists are extremely rare and shouldn’t be harmed, but propagandists are everywhere and should be hunted for sport"

Yeah..with no bag limit.



  #19   Report Post  
Old January 25th 20, 01:10 AM posted to rec.crafts.metalworking
external usenet poster
 
First recorded activity by DIYBanter: Jan 2020
Posts: 2
Default U channel and squire tube which one is strong

On 01/23/2020 05:00 AM, Gunner Asch wrote:
It also depends on the climate of the area its to be used in. Where
I live in the desert...


ayup, oilytown Taft, home of the quadracentennial Oildorado Festival,
the atmosphere lays down this protective oily grime onto purt' near
everything in sight.

it rusts so slowly that its almost not worth reapplying the galv. In
Florida..its manditory.


Ayup.
  #20   Report Post  
Old January 25th 20, 05:30 AM posted to rec.crafts.metalworking
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First recorded activity by DIYBanter: Feb 2010
Posts: 10,373
Default U channel and squire tube which one is strong

On Fri, 24 Jan 2020 16:10:47 -0800, Gunner Asch
wrote:

Path: not-for-mail
From: Gunner Asch
Newsgroups: rec.crafts.metalworking
Subject: U channel and squire tube which one is strong
Date: Fri, 24 Jan 2020 16:10:47 -0800
Organization: Organization: Coyote Engineering
Lines: 12
Message-ID:
References: irect.com





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On 01/23/2020 05:00 AM, Gunner Asch wrote:
It also depends on the climate of the area its to be used in. Where
I live in the desert...


ayup, oilytown Taft, home of the quadracentennial Oildorado Festival,
the atmosphere lays down this protective oily grime onto purt' near
everything in sight.

it rusts so slowly that its almost not worth reapplying the galv. In
Florida..its manditory.


Ayup.



Oh looky..my widdle fan boitoy appears to be back on on the street
again and posting from the local library or internet cafe. Notice he
has to use a free usenet provider to puke out his buffoonery?
He has lost all of his paid accounts for one reason or another
(snicker) and is stuck with the free ones..aioe.org....

Laughlaughlaughlaughlaughlaughlaugh. And I didnt even seek him out to
rub his nose in his ****..he came out..farted out a turd pile..and
bent over to let me slam his face into his mess.

Thanks! But you really didnt need to do that. You are simply a
momentary amusement and if you didnt stink up the room dumping your
load..Id not even be reminded of you. But hey..if you enjoy having
your own ripe slimey **** forced up your nostrils...Im game to keep
doing it.

Gunner
__

"Journalists are extremely rare and shouldn’t be harmed, but propagandists are everywhere and should be hunted for sport"

Yeah..with no bag limit.





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