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2000 GMC W4500

[486] said:
ding ding ding retard alert
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Don't be a piece of shit texbook engineer. Surely you've fucked up enough tube in your life to know that the thicker wall stuff has a pretty wide margin where it'll bend before it fucks off entirely. The fact that he's got it up the tall way isn't gonna do him any favors in this regard but with the kinds of loads that a crane will see being used in a "I can't fuck this up because this a customer's jobsite manner" he's unlikely do to any of the real stupid shit that'll get it shock loaded.

Gbkeith said:
You need to break some bigger shit.
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This is a truck crane on an Isuzu NPR and it's gonna be run by the owner, not some hired idiot. Forest for the trees man.
 
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arse_sidewards said:
Surely you've fucked up enough tube in your life to know that the thicker wall stuff has a pretty wide margin where it'll bend before it fucks off entirely.
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bends a little, center of gravity shifts, oop, instantly fifteen zillion pounds is now reaching terminal velocity
heavy lifting shit fucks off really fast, you ever tipped a gantry crane over or kinked a piece of channel steel being used as a jib wrong way round because it's easier to chain to the forks that way?
it ain't slow, moment it starts moving there ain't no stopping it
 
So, I had A.I. run the calculations and it says it's good, although I think it's hard to describe properly to be sure I'm getting accurate feedback.
 
Dethmachinefab said:
So, I had A.I. run the calculations and it says it's good, although I think it's hard to describe properly to be sure I'm getting accurate feedback.
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Don't forget that most AI as we have it now (ChatGPT etc) is a language model built to sound convincing, not correct.
You can probably ask it for the formulas, but I wouldn't trust the result of a calculation.
 
elbekko said:
Don't forget that most AI as we have it now (ChatGPT etc) is a language model built to sound convincing, not correct.
You can probably ask it for the formulas, but I wouldn't trust the result of a calculation.
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Agreed. It worked through the formulas and I ran it a few times slightly different. It gave me what i think is an incorrect answer when it calculated strength along the weak axis which was the same as the strong axis.

Convincing not correct. That's a lefty biased progressive program for sure.
 
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Tweaked it a little to receive a 4x2x3/16 box inside. I can plug weld it in a few spots and around the ends.
 
[486] said:
bends a little, center of gravity shifts, oop, instantly fifteen zillion pounds is now reaching terminal velocity
heavy lifting shit fucks off really fast, you ever tipped a gantry crane over or kinked a piece of channel steel being used as a jib wrong way round because it's easier to chain to the forks that way?
it ain't slow, moment it starts moving there ain't no stopping it
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This. It is scary how fast everything goes to shit as a shifting load increases the forces exponentially as it continues to fail/bend.
 
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Looks like a fail. Even with it plug welded to the tube, it turned into a trapezoid.

I guess I'll get some 4x2x3/8 and make some slide things to take up the slop.
 
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Something like this. I'll cut out two strips and weld them to the box tube. The receiving tube radius makes this kinda tough, I'll have to bevel the flat stock.
 
put four gibs on it, top bottom and sides
don't gotta be big pieces, just li'l tabs at the far inside end of the outside of the inside slidey tube then another four right where they'll barely be inside the outer tube when fully extended
 
Dethmachinefab said:
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Looks like a fail. Even with it plug welded to the tube, it turned into a trapezoid.

I guess I'll get some 4x2x3/8 and make some slide things to take up the slop.
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Slops not so bad. Every crane I can think of has fairly loose fitting outrigger beams.
 
[486] said:
put four gibs on it, top bottom and sides
don't gotta be big pieces, just li'l tabs at the far inside end of the outside of the inside slidey tube then another four right where they'll barely be inside the outer tube when fully extended
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Problem I have with just taking up the space is I need it to resist a twisty motion as well. That makes me have to get something up in the corners. Hard to explain without wiggling it, but enough space to slide nice and not enough to twist.
 
Dethmachinefab said:
Problem I have with just taking up the space is I need it to resist a twisty motion as well. That makes me have to get something up in the corners. Hard to explain without wiggling it, but enough space to slide nice and not enough to twist.
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you aren't thinking like a snap-on engineer designing the whiz bang new for 1962 socket line

"flank drive" man,
flank drive
 
Dethmachinefab said:
Agreed. It worked through the formulas and I ran it a few times slightly different. It gave me what i think is an incorrect answer when it calculated strength along the weak axis which was the same as the strong axis.

Convincing not correct. That's a lefty biased progressive program for sure.
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At the risk of going massively OT...

Not everything is a political conspiracy :homer: ChatGPT is a statistical language model, it basically just calculates which letter/word is most likely to follow the previous. That statistical model has been trained on millions of texts, including the internet.

The fact that it works as well as it does is amazing enough, but it being a language model means it doesn't really know how to do actual math. At least, not yet.

Anyway, on with the cool build!
 
So nothing much has been accomplished. I did scrap another outrigger design. Now I'm just going to go with some uhmw sliders to pack out the difference and be done with it.

Trucks been running good so far but I keep getting the low brake vacuum warning buzzer. I adjusted the brakes and the pedal is much better but the annoying buzzer remains. I'll have to check for a leak, kick up the rpms and it's ok.
 
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A little progress. Got the boxes built and stuck on the tubes, they still need the top caps. Mounted a jack so I can measure where the support ring will go that holds the top of the cylinder in place. Just a little ring to index the back side of the cylinder that will be welded under the cap.
 
Fucked up. Forgot to put the slider bits on before welding the boxes onto the tube. Like the good flare but no nut situation. I cut off part of the rear slider and can trim the outer lower one to remedy this. I hate this thing.
 
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