Labor savin' devices

"Ned Simmons" wrote in message wrote:
A potential failure mode of a slender beam is somewhat analogous to column buckling. https://en.wikipedia.org/wiki/Buckling#Lateral-torsional_buckling
==============================That could particularly be a problem for a beam made from two channels that are loaded near the outer edge of the lower flange, although when I tested for it by leaving out the bolts that join the webs the channels deflected to nearly the max extreme fiber stress for A36 steel without twisting. I had turned the trolley wheels to match the flange angle so they rode on their inner edges if the flange twisted downward. The channels also didn't twist much when I bent them beyond the yield point to straighten them.
The Harbor Freight 1300# electric hoist starts with a jerk that noticeably increases the deflection of the beam. I didn't measure the deflection because I don't want to be that close on a stepladder if anything fails.

On Mon, 7 Sep 2020 13:15:26 -0400, "Jim Wilkins"
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Yes, I'm pretty sure the tables assume the load is applied in line with the beam's neutral axis, so an eccentric load will make matters worse.
It's been a long time since I've designed any lifting gear for others (and when I did I had a structural PE review the designs), but my recollection is that the codes require the "jerkiness" of the load be considered when choosing a factor of safety. When it's not yourself, there's not much you can do much about the jerkiness of the operator.

"Ned Simmons" wrote in message
It's been a long time since I've designed any lifting gear for others (and when I did I had a structural PE review the designs), but my recollection is that the codes require the "jerkiness" of the load be considered when choosing a factor of safety. When it's not yourself, there's not much you can do much about the jerkiness of the operator. Ned Simmons
==========================If I measure the maximum deflection by having a wire on the beam scratch a fixed smoked surface could I relate it to extreme fiber stress with an online calculator that shows both? Or am I missing something?

On Wed, 9 Sep 2020 12:39:07 -0400, "Jim Wilkins"
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The short answer is, yes, that'll work for small deflections of straight beams. The only time I can remember actually comparing calculated vs. actual strain (strain = stress/modulus of elasticity) was in a Strength of Materials lab. I have had a chance to compare the actual and calculated deflection of simple well characterized beams a couple times, and the agreement was quite close. But the devil is in the details. Deviation of the supports, beam section dimensions, and loading details from the assumed ideals may introduce significant errors.
You could brew up your own brittle strain indicating coating. https://stresscoat.com/ https://www.sciencedirect.com/topics/engineering/experimental-stress-analysis

"Ned Simmons" wrote in message wrote: ...............
The short answer is, yes, that'll work for small deflections of straight beams. The only time I can remember actually comparing calculated vs. actual strain (strain = stress/modulus of elasticity) was in a Strength of Materials lab. I have had a chance to compare the actual and calculated deflection of simple well characterized beams a couple times, and the agreement was quite close. But the devil is in the details. Deviation of the supports, beam section dimensions, and loading details from the assumed ideals may introduce significant errors.
You could brew up your own brittle strain indicating coating. https://stresscoat.com/ https://www.sciencedirect.com/topics/engineering/experimental-stress-analysis

On Fri, 11 Sep 2020 07:34:33 -0400
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Most common knots weaken the strength of the "rope". If you do some research in better knot tying books you can find some that maintain more of the ropes strength ;-)

"Leon Fisk" wrote in message wrote:
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Most common knots weaken the strength of the "rope". If you do some research in better knot tying books you can find some that maintain more of the ropes strength ;-)

"Leon Fisk" wrote in message wrote:
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Most common knots weaken the strength of the "rope". If you do some research in better knot tying books you can find some that maintain more of the ropes strength ;-)
Leon Fisk Grand Rapids MI
===========================When working with a crew if I spend more than 5 seconds tying a knot they start joking about my "fancy French knots", so I keep them quick and simple or else call them by their European names, like "noeud de chaise." I've had helpers become very offended when they saw me tying knots they didn't know.

On Fri, 11 Sep 2020 13:43:20 -0400
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Saw your other response too... Figured you knew what you were doing and had researched it for best practices ;-)
I can imagine there was considerable slack time during long ocean voyages. Industrious sailors would practice, observe and develop new knots to try out and amuse each other.
The Ashley Book of Knots has a lot of info and amusing anecdotes to peruse...

"Leon Fisk" wrote in message wrote: ..................
Saw your other response too... Figured you knew what you were doing and had researched it for best practices ;-)
I can imagine there was considerable slack time during long ocean voyages. Industrious sailors would practice, observe and develop new knots to try out and amuse each other.
The Ashley Book of Knots has a lot of info and amusing anecdotes to peruse...
Leon Fisk Grand Rapids MI
===========================When I was young, adventuresome and less injured I hiked all over the mountains here and learned what I could of rock and ice technical climbing equipment, and that I'm not agile or daring enough to try them. Surprisingly riding in Army helicopters didn't trigger my usual fear of height, even when a pilot demonstrated a hot LZ approach by suddenly rolling 90 degrees sideways and spiraling down in free fall. https://www.mountainproject.com/area/105872225/new-hampshire
I climbed Mt Washington on an October day that was too cold, wet and miserable to drive up, though hundreds hiked it.

On Fri, 11 Sep 2020 15:20:16 -0400, "Jim Wilkins"
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I hiked to the top of Mt. Washington on a July day like that. We camped a mile or two below Lakes of the Clouds and sprinted to the summit with daypacks on a gorgeous day. While sitting in the snack bar the clouds rolled in and next thing we were in a whiteout worrying about getting back to our camp in a blizzard with no gear. Or worse, spending the night in the "Dungeon" at Lakes of the Clouds hut.
https://www.youtube.com/watch?v=rqmQ6eniFhc

About 15 minutes later the snow stopped, the sky cleared, and it was a beautiful summer day again.

"Ned Simmons" wrote in message wrote:
........................ The AISC steel construction manual's beam tables & graphs take the beam's unbraced length into account.
Also keep in mind that both the AISC and (I presume) that calculator use a factor of safety of 1.67. The FS for a lifting device is typically much greater.
Ned Simmons
==================I have the 1970 edition, which should be good enough because I use old steel.
https://www.academia.edu/34601167/Steel_construction_manual_fourteenth_edition_american_institute_of_steel_construction

On Mon, 7 Sep 2020 20:22:20 -0400, "Jim Wilkins"
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You probably have the same edition as mine, the 7th. I took Steel Structures around 1973.

On Sun, 6 Sep 2020 10:01:48 -0400, "Jim Wilkins"
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W-folding step ladder?
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Yup, whatever works.
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Handy link.

On Mon, 14 Sep 2020 15:59:54 -0700, Larry Jaques wrote:
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Presumably one of those that has 3 hinge joints. Each joint latches at several different angles in a 180-degree range. The center hinge faces "up" and the other two "down" (or vice versa) allowing a V fold (like usual stepladder) or a W fold or like an L (useful for under an eave) or like a C (sawhorse)
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"James Waldby" wrote in message On Mon, 14 Sep 2020 15:59:54 -0700, Larry Jaques wrote:
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Presumably one of those that has 3 hinge joints. Each joint latches at several different angles in a 180-degree range. The center hinge faces "up" and the other two "down" (or vice versa) allowing a V fold (like usual stepladder) or a W fold or like an L (useful for under an eave) or like a C (sawhorse)
===============================Right. Unlike a regular stepladder they have no cross brace and can be lifted over the beam.
I always wonder how much should be explained for the muggles so I keep descriptions brief and watch for the questions. I'm of the engineer/scientist sort who communicates best through sketches.

On Tue, 15 Sep 2020 06:50:39 -0400, "Jim Wilkins"
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Oh, yeah. I think I saw something like that in a very lightweight version 30 years ago. All the newest have a hinge in the middle and two extendable/removable outer sections. (I got an $89 Cosco, near identical to a $300 Little Giant 17') Oh, I did find your style after all. https://amzn.com/B0151HKZ4W They're stronger than I last saw.
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Muggles? (grumble,grumble)

"Larry Jaques" wrote in message
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Oh, yeah. I think I saw something like that in a very lightweight version 30 years ago. All the newest have a hinge in the middle and two extendable/removable outer sections. (I got an $89 Cosco, near identical to a $300 Little Giant 17') Oh, I did find your style after all. https://amzn.com/B0151HKZ4W They're stronger than I last saw.
===============================That's the type. Mine's older and has the wide foot on one end only, so I added another to make it more stable on dirt. Its round rungs hurt my feet unless I'm wearing thick-soled boots. A neighbor left his outdoors and the hinge latch mechanisms became hard to operate. The only easy way I've found to carry it any distance is open as a step ladder, horizontal, with a hand at the balance point on each leg.

On Fri, 2 Oct 2020 20:21:44 -0400, "Jim Wilkins"
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I've found that the easiest way to carry the Cosco (4.5' tall collapsed) is to bend down, reach my arm completely into the space between the rungs, and grab a rung with my hand. With a thick jacket on, I can rest it on my shoulder. Otherwise, I carry it with my bicep. Carrying it open is OK, too. I put a stabilizer on the top end of mine which keeps the end off the wall, making it easier to paint under it. Ditto needing hard-soled boots, but half the rungs on the Cosco have flat tops, so I try to stay on them. TIP: Don't stand on a ladder in suede moccasins to paint.

"Snag" wrote in message
Ive ordered a battery for this , will be kept on a trickle charger most of the time . I won't be getting anywhere near the capacity of the winch as a general rule . If i decide the battery isn't working out , I have a backup plan to draw power from the camper's deep cycle battery . I need to find some more 8 ga or heavier wire for the hookup , I'm a few feet short . I'm undecided about how to handle the power hookups when it's not on the crane base .