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 March 22nd 21, 11:59 PM posted to rec.crafts.metalworking
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Default gantry - channel sections

"Jim Wilkins" wrote in message ...

I've returned to the gantry track splice, after fixing the car to pass
inspection and largely completing my taxes.

Have you ever seen a bolted I beam splice with the flanges thickened with
welded plates or such to compensate for the reduction in area at the bolt
holes?


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Old March 23rd 21, 02:19 PM posted to rec.crafts.metalworking
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Default gantry - channel sections

"Jim Wilkins" wrote in message ...

"Jim Wilkins" wrote in message ...

I've returned to the gantry track splice, after fixing the car to pass
inspection and largely completing my taxes.

Have you ever seen a bolted I beam splice with the flanges thickened with
welded plates or such to compensate for the reduction in area at the bolt
holes?

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

If welding plates on the outside of the channel flanges to thicken and
strengthen them at the central splice is technically (if not economically)
sound, they provide much more thread engagement for splice plate bolts in
tapped holes, that don't interfere with the trolley wheels rolling on the
lower flange.

All the examples I've found of bolted beam splices accept the loss of net
flange area at the bolt holes and instead suggest locating the splices away
from the most heavily stressed parts of the beam.

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Old March 23rd 21, 03:09 PM posted to rec.crafts.metalworking
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Default gantry - channel sections

On Tue, 23 Mar 2021 09:19:51 -0400
"Jim Wilkins" wrote:

If welding plates on the outside of the channel flanges to thicken and
strengthen them at the central splice is technically (if not economically)
sound, they provide much more thread engagement for splice plate bolts in
tapped holes, that don't interfere with the trolley wheels rolling on the
lower flange.

All the examples I've found of bolted beam splices accept the loss of net
flange area at the bolt holes and instead suggest locating the splices away
from the most heavily stressed parts of the beam.


A patent here that uses wedges or teeth on plates and beams that would
transfer stress over a broader area:

https://patents.google.com/patent/US20030129026A1/en

Maybe poke around in the patents for a bit, give you some more ideas to
work with...

--
Leon Fisk
Grand Rapids MI

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Old March 24th 21, 01:04 AM posted to rec.crafts.metalworking
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Default gantry - channel sections

"Leon Fisk" wrote in message ...

On Tue, 23 Mar 2021 09:19:51 -0400
"Jim Wilkins" wrote:

If welding plates on the outside of the channel flanges to thicken and
strengthen them at the central splice is technically (if not economically)
sound, they provide much more thread engagement for splice plate bolts in
tapped holes, that don't interfere with the trolley wheels rolling on the
lower flange.

All the examples I've found of bolted beam splices accept the loss of net
flange area at the bolt holes and instead suggest locating the splices away
from the most heavily stressed parts of the beam.


A patent here that uses wedges or teeth on plates and beams that would
transfer stress over a broader area:

https://patents.google.com/patent/US20030129026A1/en

Maybe poke around in the patents for a bit, give you some more ideas to
work with...

--
Leon Fisk
Grand Rapids MI

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

From my reading it appears that a properly designed, prepared and torqued
slip-critical splice joint is as strong as the undrilled flanges, due to
friction around the bolts. One suggested preparation is to wire brush the
loose rust off by hand, but not with a power brush which makes the surfaces
too smooth.

I expect to have to customize the bolts to ensue their shear planes pass
through the full shank diameter, IOW extend the threads up a longer shank
and cut the bolt short, so I want them and their tapped holes reuseable and
won't tighten them anywhere near the yield point. Also the rust inhibitor I
use on outdoor steel and galvy dries to a soft wax that works fairly well as
a high pressure lubricant. The splice will have to depend on bolt shear and
bearing.

That grooved pattern is used to locate top jaws for lathe chucks. I've
considered other proven interlocking patterns such as the Christmas tree
that retains turbine blades and the doll's head on double shotguns. I don't
have CNC and doubt I could mill them accurately enough to share the load and
keep the splice from sagging. However I can custom-fit bolts tightly enough
to keep the joint snug and straight, as on my 3" gantry and sawmill's track.

I think I could make and weld on a multi-leaf knuckle joint (pinned hinge)
though its height would require a custom lowered bar between the trolley
side plates.

Incidentally, while researching bolt and rivet patterns I found that Titanic
was joined with strong steel rivets in the center but softer hand-set
wrought iron ones at the end where the hydraulic riveter wouldn't fit:
https://www.gjenvick.com/OceanTravel...gTheHulls.html

There is survivor testimony and sonar evidence that the hull plate seam(s)
opened from near the bow to all the way back to the forward coal bunker in
boiler room 5, half way between the first and second funnels, and possibly
into the piping space below the floor in boiler room 4 behind it, at the
base of the second funnel. A gap that long that averages the width of a
finger would account for the rate of flooding. Such extensive hull breaches
flood modern passenger ships, namely the Costa Concordia and Mikhail
Lermontov. (DUH!)

Britannic, the last of the trio, was modified during construction to cure
Titanic's flaws. Nevertheless, during WW1 she hit a mine, was damaged in the
same places, and sank twice as fast.

Olympic, the first, survived two of the normally expected ship-to-ship
collisions, smacking into huge immobile white icebergs being either very
rare or a cause of mysterious unexplained all-hands losses. The second was
with an attacking U-boat that slid under the hull into the propellers,
though some of its crew lived. Olympic was dinged but didn't leak and
remained in service well into the Depression.

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Old March 24th 21, 01:52 PM posted to rec.crafts.metalworking
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Default gantry - channel sections

"Leon Fisk" wrote in message ...
....
A patent here that uses wedges or teeth on plates and beams that would
transfer stress over a broader area:
....

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

I don't have the shop space to clamp one end of an 8' beam in my mill vise
to accurately drill a hole pattern. All I can do is hang the opposite end at
an angle in a doorway and locate a punch mark or pilot hole under the
spindle to drill it larger. The splice plate will have to be match-drilled
to beams on sawhorses out in the driveway. Either a Portalign or clamped-on
bench drill press will keep the bit, hole and tap square to the surface. I
use an adjustable hand reamer to give bolt shanks the minimum of clearance.

That's how I spliced 8' sections of 3" channel into the sawmill track and
overhead gantry, but those splices have to sustain only the dead weight of
the channels while I'm setting up and leveling them, they are supported at
the splice in service. I'm trying to splice the 4" channel strongly enough
that it doesn't need a center support although it will normally have one.
The problem is designing a tension-side joint that gives the full strength
of the channel without blocking the trolley.
https://www.harborfreight.com/1-ton-...ley-97392.html

If I just weld them together or buy a suitable 16' beam the assembly is too
large to store under cover and too heavy to carry and lift into place. One
8' section of the 4" channel is hard enough to support and align with one
hand while inserting a bolt with the other, on a stepladder. When possible I
turn a taper and a root-diameter pilot on the ends of machine screws to help
align tapped and clearance holes in things I repeatedly assemble and
disassemble outdoors, like my 50' TV antenna mast, but there isn't enough
clearance for that between the trolley wheels.

The problem could be worse. I had the chance to examine and ride in a Beech
18 whose original wing spars had been stiffened with a similar-sized steel
reinforcing strap underneath. It makes an un-aerodynamic bulge in the lower
wing surface.
http://www.twinbeech.com/sparstrap.htm

"Other manufacturers kits resemble bridge trusses and can protrude more than
10 inched from the skin of the Beech. Not only is this unsightly but it is
enough to make an aerodynamicist sick. I heard one owner say that one good
thing about his bridge truss spar strap was that if he ever had to belly
land his Beech at least the props wouldn't hit the ground!"



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Old March 26th 21, 05:45 PM posted to rec.crafts.metalworking
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Default gantry - channel sections

"Jim Wilkins" wrote in message ...

The problem is designing a tension-side joint that gives the full strength
of the channel without blocking the trolley.

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

Am I correct in assuming that thickening the outside of the channel flange
with a welded-on shim to restore the area lost to bolt holes and sizing the
joining plate to at least that same net cross-sectional area is enough?

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Old March 27th 21, 01:20 AM posted to rec.crafts.metalworking
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Default gantry - channel sections

"Jim Wilkins" wrote in message ...


The problem is designing a tension-side joint that gives the full strength
of the channel without blocking the trolley.

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

Am I correct in assuming that thickening the outside of the channel flange
with a welded-on shim to restore the area lost to bolt holes and sizing the
joining plate to at least that same net cross-sectional area is enough?

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

This is similar to a filler plate in a splice between beams of different
heights. Are filler plates ever welded to the smaller beam?

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Old April 15th 21, 06:48 PM posted to rec.crafts.metalworking
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Default gantry - channel sections

This is a half section of my present gantry hoist track splice design. C is
the 4" channel, V the 3/8" thick central splice plate between the channels,
H the 3/8" thick horizontal splice plate under the tension flanges and A the
angle iron splice above the compression flanges.

My question is how to weld the inverted T joint between V and H. I think an
inside fillet weld will deform H upward and require grinding off the sharp
and square lower corners of the channel. Is a row of plug or slot welds in H
a reasonable alternative to avoid distortion and interference?

The 6" high vertical center plate V alone has nearly the same Ixx as the two
channels so I don't think welding it to H is essential but connecting them
should make the joint stiffer and one-man assembly easier. The angle A on
top bolts to V and C afterwards, and gives the central hanger shackle pin
more bearing area than V alone would.

VA
VA
VA
VAAAAAA
VCCCCCC
VC
VC
VC
VC
VC
VCCCCCC
HHHHHH

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Old April 16th 21, 10:49 AM posted to rec.crafts.metalworking
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Default gantry - channel sections

"Jim Wilkins" writes:

This is a half section of my present gantry hoist track splice
design. C is the 4" channel, V the 3/8" thick central splice plate
between the channels, H the 3/8" thick horizontal splice plate under
the tension flanges and A the angle iron splice above the compression
flanges.

My question is how to weld the inverted T joint between V and H. I
think an inside fillet weld will deform H upward and require grinding
off the sharp and square lower corners of the channel. Is a row of
plug or slot welds in H a reasonable alternative to avoid distortion
and interference?

The 6" high vertical center plate V alone has nearly the same Ixx as
the two channels so I don't think welding it to H is essential but
connecting them should make the joint stiffer and one-man assembly
easier. The angle A on top bolts to V and C afterwards, and gives the
central hanger shackle pin more bearing area than V alone would.

VA
VA
VA
VAAAAAA
VCCCCCC
VC
VC
VC
VC
VC
VCCCCCC
HHHHHH


Is what you aim for structurally necessary or helpful is a good first
question given the work involved...

OK - using your notation and adding W for weld


...
VC
VC
VCCCCCC
WHHHHHW

So you now have the "H" as two strips with the inner edge bevelled
about 30deg.
Set with a root gap at least equal to the middle "V" plate. Wider and
you "get" some of the "C" channel.
Weld-up. Left and right corners and if necessary middle run for first
layer, then fill.

If "H" is a tension "doubler", not otherwise part of the beam "Second
Moment of Area", then just fillets at the ends would do?
Maybe small fillets along sides, out to edges of the "C" (channel)
sections?
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Old April 17th 21, 12:59 AM posted to rec.crafts.metalworking
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Default gantry - channel sections

"Richard Smith" wrote in message ...

"Jim Wilkins" writes:

This is a half section of my present gantry hoist track splice
design. C is the 4" channel, V the 3/8" thick central splice plate
between the channels, H the 3/8" thick horizontal splice plate under
the tension flanges and A the angle iron splice above the compression
flanges.

My question is how to weld the inverted T joint between V and H. I
think an inside fillet weld will deform H upward and require grinding
off the sharp and square lower corners of the channel. Is a row of
plug or slot welds in H a reasonable alternative to avoid distortion
and interference?

The 6" high vertical center plate V alone has nearly the same Ixx as
the two channels so I don't think welding it to H is essential but
connecting them should make the joint stiffer and one-man assembly
easier. The angle A on top bolts to V and C afterwards, and gives the
central hanger shackle pin more bearing area than V alone would.

VA
VA
VA
VAAAAAA
VCCCCCC
VC
VC
VC
VC
VC
VCCCCCC
HHHHHH


Is what you aim for structurally necessary or helpful is a good first
question given the work involved...

OK - using your notation and adding W for weld


...
VC
VC
VCCCCCC
WHHHHHW

So you now have the "H" as two strips with the inner edge bevelled
about 30deg.
Set with a root gap at least equal to the middle "V" plate. Wider and
you "get" some of the "C" channel.
Weld-up. Left and right corners and if necessary middle run for first
layer, then fill.

If "H" is a tension "doubler", not otherwise part of the beam "Second
Moment of Area", then just fillets at the ends would do?
Maybe small fillets along sides, out to edges of the "C" (channel)
sections?

-------------------
I was expecting to do just that until I cleaned up the rusty channels and
found that the flanges are square to the web and a one-piece H plate fits
flush on both sides.

This with an abrasive fiber pad stripped the rust remarkably fast and
effectively and was easier to control than a 7" angle grinder.
https://www.harborfreight.com/air-an...der-93629.html

The 100kg track and hoist assembly has to come apart for handling and
storage so the channels can't be welded to the splice.

If the angle between H and V initially matches the outsides of the channel,
would it increase or decrease after filling the gap?

If the angle opens a little the channel would still bear solidly on H at the
root which may be acceptable. If the angle closes the channel will contact H
at the outer edge and shift under load. I don't have a press large enough to
bend 3/8" plate.

I considered plug welds assuming I could fill a 3/8" hole in one pass and
the weld would shrink symmetrically as it cooled, and the surrounding solid
metal would minimize distortion.

The plates and channels would be clamped together with a gap between the
channels under the weld. I could stop drilling and filling if the plates
began to warp out of alignment.



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