whit3rd writes:

On Sunday, November 15, 2020 at 2:14:47 PM UTC-8, Richard Smith wrote:
Is "polish and coat with a hard brittle varnish" the answer to this
question?

I've made a "square-cornered U" of RHS100x50by8thk (4"x2"by5/16"thk.).
45degree mitres full-pen'd for the two corners.
...
I'd like to put a hydraulic cylinder / hydraulic jack toward the open
end of the parallel sections forming the "U", and see what happens
when it's increasingly loaded.

Precautionary note - one assumes it would be a good idea to lash the
hydraulic cylinder with rope to constrain it if it were elastically
ejected from its original position...

If things go well and forces pass those necessary to cause yielding -
how would one reveal where that plastic yielding is happening?
I've heard of polish surfaces smooth and apply a hard brittle
lacquer...

I'd think, in testing-machine fashion, you'd want to step the pressure (good
hydraulic gage required for that) while watching a machinist's dial gage on the
deflection. You know what direction it moves... no need for a two-D grid,
and buckling would require 3-D before-and-afters.
Do multiple pressure trials, relieving pressure and looking for permanent deflection.

I'm not sure I could get full penetration on those internal corners, but maybe cut-a-slot/insert-a-wedge
in two or three places could make a U with continuous inner metal, all the welds being under some
amount of compression. You'd want to hot-work the bends, of course.

Thanks for responses. Things moved on a long way quickly.

This is the write up about what I was then in the early stages of...
http://www.weldsmith.co.uk/tech/stru...lyse_test.html

This one gets testing conditions directed at the test weld
http://www.weldsmith.co.uk/tech/stru...beam_test.html
The Lu..ders Bands spall the mill scale - "witnesses" the deformation
penetrated around the weld.
Found what I wanted...
Rich S

"Richard Smith" wrote in message ...


This one gets testing conditions directed at the test weld
http://www.weldsmith.co.uk/tech/stru...beam_test.html
The Lu..ders Bands spall the mill scale - "witnesses" the deformation
penetrated around the weld.
Found what I wanted...
Rich S

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

An Umlaut replaces an "e" after the vowel, as in Lueders. Common usage at
least in the US is to ignore foreign accent marks and pronunciations,
despite our large immigrant population.

Good job. Too bad the mill scale didn't crack -before- reaching the yield
point, that would have been valuable.

Perhaps you've seen a good solution to a similar problem I'm working on. I
want to join four 8' C4x5.4 channels into an overhead gantry hoist track 16'
long, ie two back-to-back pairs non-permanently joined in the middle. I'm
not using a single WF beam because I need each component including the
splice to be light enough to carry and lift overhead, as it will be stored
disassembled and possibly assembled on a stepladder.
http://www.toolsforengineer.com/c4x5-4/

I'd like the central splice to maintain the load capacity of the channels,
meaning (I think) no bolt holes that weaken the tension flanges (doublers?).
Also the hoist trolley has to roll on the top side of the lower flanges
without obstruction. I don't know how to design for full strength with bolts
through only the webs and upper compression flanges. The trolley doesn't
leave much clearance under the beam for the welded-on leaves of a pinned
joint.

The main intended use has it hanging from an overhead beam at the splice, so
the minimum design has to support only the load's reaction or the moment of
the dead weight during setup.

A full strength splice is really just a design exercise, though it would be
useful if I suspend the track from end tripods in the field, or my yard,
where I just finished man-handling and sawing 3/4 ton oak logs into beams
and have two one-tonners to attack in the Spring.

... An Umlaut replaces an "e" after the vowel, as in Lueders. ...

You remind me of the common way of substituting for an umlaut

"Boehler" rather that (phonetic representation of the common
pronounciation) "bowler".

The "umlaut'ed" vowel sound is unique, isn't it? Not literally
represented by removing the umlaut and suffixing with an "e"?

That was alright. Turkish was "the greatest fun". Full respect for
the language. I could never do more than catch buses, shop, order
meals, etc., extend greetings and simple invitations - but actually
rendering those in a conversational way which blended into the flow of
everytday events... Lots of sounds in this Middle Eastern language
which we don't have. Then their best - they have all these grammatic
rules so that say two words convey what we need seven to do - and the
vowel sounds harmonise through those words. The mind was on a really
thrilling twisting multi-dimensional ride flying all that while you
responded to someone who asked if the chair here was free (would they
be invited to share this table in a cafe full of people having
breakfast on their way to work), etc.

Regards,
Rich S

PS - I will try to understand your technical challenge / question.
Tired after a working week.
Bit later...

"Richard Smith" wrote in message ...

... An Umlaut replaces an "e" after the vowel, as in Lueders. ...

You remind me of the common way of substituting for an umlaut

"Boehler" rather that (phonetic representation of the common
pronounciation) "bowler".

The "umlaut'ed" vowel sound is unique, isn't it? Not literally
represented by removing the umlaut and suffixing with an "e"?

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

I was stationed in Heidelberg and points south, where the Schwaebisch
dialect is VERY different from standard German, and the neighboring Bavarian
isn't much better.
https://omniglot.com/language/phrases/bavarian.php

I still can't distinguish between Hochdeutsch and a Swiss or Austrian
accent. My German pronunciation is a mix of two years of it in college and a
smorgasbord of what I heard.

"Richard Smith" wrote in message ...

PS - I will try to understand your technical challenge / question.
Tired after a working week.
Bit later...
-------------------------------------

The 16' gantry hoist track of C4x5.4 channel is for my sawmill. It will hang
at its center joint from the front roof beam of a storage shed for 12' long
timbers, with 8' of track outdoors over the sawmill to gently load logs onto
it, and the other section inside to stack the results. Both ends hang from
10' tripods, probably raised and suspended by cables of boat trailer winches
that allow for leveling and readjustment as the tripod legs sink into the
dirt. For this use the 8' track sections could simply be pinned or hinged at
the center but a stiff connection makes the track easier to install by
assembling it on sawhorses and lifting the ends. I avoid muscling heavy
steel into place while on a ladder. I usually work alone since the available
help isn't up to complex tasks like tying a knot.

The holes drilled in the channels for this supported center splice shouldn't
interfere with making the stronger unsupported splice I asked about. I
should at least have a good plan for it. Ideally the same splice assembly
could serve both uses, however the unsupported splice could arch above the
track and the centrally supported one needs to be low to allow more working
height for the hoist. Perhaps a bolt-on upper truss allows both?

My question is how to splice the channels without weakening the tension
flanges with bolt holes or interfering with the trolley or its wheels. Can
it be done with bolts through the web? If a doubler welded to the lower
flange is acceptable to maintain cross-sectional area around bolt holes, is
there a right/wrong way to weld it without inadvertently adding a stress
riser? I need a good overall geometry before calculating the details. There
aren't many exposed steel structures around here to examine for clever
ideas.

The trolley can be adjusted to clear bolts and nuts joining the webs to a
central vertical plate, as on the center splice in the 3" channel. I have
about 3' of W6x9 beam that could be reinforced to make the splice. My other
scrap structural steel is too heavy to hold in place with one hand while
inserting a bolt, and the steel shop where I buy offcuts doesn't have
smaller than W8x15.

The shed that stores 12' beams is 19' long by 4' wide, built narrow between
two stabilizing end trees to quickly dry freshly cut firewood. The track
extends 4' out the back side, over space for a narrow trailer that moves
logs and lumber.

I've already borrowed and used the 3" x 16' channel gantry track from a shed
that stores 8' lumber but I really need both shed gantry hoists functional
at the same time. The C3x4.1 channel has a decent safety margin to lift 8'
logs but not 12' ones. I have a 1000 kg crane scale to weigh the loads and
stay within my equipment's capacity.

Great question, but been distracted
("weldsmith" is my site)

New section - "structures"
http://www.weldsmith.co.uk/tech/struct/struct.html

Linking from it -
Three new projects

http://www.weldsmith.co.uk/tech/stru...lyse_test.html

http://www.weldsmith.co.uk/tech/stru...beam_test.html

http://www.weldsmith.co.uk/tech/stru...4_fwbeamt.html
"Fillet welds tensile tested in beam test"

Been busy most of the weekend, and working in a steel fab. shop during
the week.

Saw that "C3x4.1" is a channel.
We have "PFC" - "Parallel Flange Channel".
That looks like a tapered-thickness flange specification(?)

"Richard Smith" wrote in message ...

Great question, but been distracted
("weldsmith" is my site)

New section - "structures"
http://www.weldsmith.co.uk/tech/struct/struct.html

Linking from it -
Three new projects

http://www.weldsmith.co.uk/tech/stru...lyse_test.html
RS
---------------------------------------------------
JSW
I went through a similar process for the frame of the hydraulic bucket
loader I built for my tractor. The square tubing U frame serves as the
hydraulic reservoir so all welds had to be oil-tight as well as strong
enough to withstand the bucket hitting an immovable rock. It did, and the
frame welds held.

To clear the front wheels when turning I had to angle the corners up at 60
degrees from just outside the tractor's frame, then further up, turn another
30 degrees to upright, thus there were four beveled butt joint welds to leak
and more chance of distortion. After welding on the cylinder attachments etc
the top ends bent inward and I had to jack them back to parallel so the boom
pivot pins at the tops of the frame would be in line.

I used a hydraulic pump and cylinder similar to yours, with a
hydraulic-rated tee and a pressure gauge inserted between the pump outlet
and the hose. Afterwards I removed it because the gauge was too susceptible
to damage* if the stiff, springy hose tipped the pump over.

Since the goal was to make both legs parallel I measured the spring-back
from beyond the yield point and jacked the legs that far beyond parallel.
The gauge wasn't much more useful than the feel of the pump handle to
indicate yield.

* These disassemble gauges for repair and recalibration. I made one last
week from scrap 3/8" water pipe.
https://www.amazon.com/SDENSHI-Multi.../dp/B07YX3MJPC
A bag of similar home-made tools got me a job at Segway.
JSW
---------------------------------------------------
RS
Saw that "C3x4.1" is a channel.
We have "PFC" - "Parallel Flange Channel".
That looks like a tapered-thickness flange specification(?)
RS
---------------------------------------------------
JSW
Yes it is, the channels are former pallet rack horizontals from a recycling
company. I assume 36KSI yield for them, unless proof testing shows
otherwise. I didn't measure the force to straighten the bent ones because
the setup made a formidable crossbow as-is and didn't need a projectile.

My question is if you've seen some clever way to splice beams with bolts (or
rivets) without drilling and weakening the tension flange. The pinned fork
joints that connect mobile crane sections might do if there could be enough
clearance underneath for the trolley.

"Richard Smith" wrote in message ...

http://www.weldsmith.co.uk/tech/stru...4_fwbeamt.html
"Fillet welds tensile tested in beam test"

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

That's interesting. The weld test I was expected to pass was a butt joint
with 7018 that could survive being folded double on a 50 ton press. The
practice steel was 3/16" (5mm) hot rolled CNC plasma cutouts from a
reputable metal fab company so I assume it was properly specified, not the
random junk I usually use. It did harden at the plasma cut.

Out of curiosity I tried the test on a 1/4" grade 8 bolt. The rolled threads
were brittle but the shank bent into a U without cracking.

Cooking steel overnight in the wood stove softens it nicely for machining.
Yesterday I hot forged an old lawnmower blade flat and began hacksawing out
thin wrench blanks. If the steel doesn't dull a 10-for-$1 hacksaw blade it
should be safe to cut with a $25 bandsaw blade.