Quick steel strength question??

[Corwin C]

OK ... due to popular demand by PM ... I will attempt to calculate the moment of inertia for the welded configurations ...

Now ... if the stacks are attached rigidly (i.e. welded) it creates a whole new monster that would require modifying the equation a little (I'm willing if anyone wants it, right now I feel lazy.) I believe, however, that the 1x2's stacked on top of each other and rigidly welded would be very slightly higher than the 2x2 (I'm guessing less than 102% of the 2x2), and the 1x2's stacked side by side would be essentially the same as they are without being welded because there is essentially no shear between the parts (122% of the 2x2).

The welded configurations are essentially a 2x2 with a web inside. The web is the size of the interior of the tubing x twice the thickness. Therefore the moment of inertia will be the moment of inertia of the 2x2 (0.3702 in^4) plus the moment of inertia of the web (I = 1/12[bh^3]) ... I'm also assuming that the weld is perfect and allows absolutely no movement (shear) between the parts.

2 - 1"x2" welded horizontal:
I = 1/12[1.8438*(0.0781*2)^3]+0.3702 = 0.3708 in^4

2 - 1"x2" welded vertical:
I = 1/12[(0.0781*2)*1.8438^3]+0.3702 = 0.4518 in^4

Here's my final, final comparison. (added decimals to show how close the horizontal configurations were)
2"x2" = 0.3702 in^4
1"x2" vertical = 0.2259 in^4 or 61.02% of the 2x2. Two stacked side by side would be 122.04% of the 2x2.
1"x2" horizontal = 0.0744 in^4 or 20.10% of the 2x2. Two stacked on top of each other would be 40.20% of the 2x2.
drumroll please...
2 - 1"x2" horizontal welded = 0.3708 in^4 or 100.16% of the 2x2.
2 - 1"x2" vertical welded = 0.4518 in^4 or 122.04% of the 2x2.

There you go Gus ... I actually over estimated the strength of the horizontal welded configuration.

[kennyrayandersen]

OOPS. Mea Culpa! Thanks for the correction. I have this HP48G at home because the 7-9 keys quit working so well. I thought I watched the input closely and I did bang it on the floor to get it working smoothly, or so I thought. The 48G I have at work is a NOS unit that I’ve only been using for a couple of years and it’s OK! Next time I’ll use a spreadsheet at home and I suppose I should throw that bad HP away before someone get hurt!

[Corwin C]

OOPS. Mea Culpa! Thanks for the correction. I have this HP48G at home because the 7-9 keys quit working so well. I thought I watched the input closely and I did bang it on the floor to get it working smoothly, or so I thought. The 48G I have at work is a NOS unit that I’ve only been using for a couple of years and it’s OK! Next time I’ll use a spreadsheet at home and I suppose I should throw that bad HP away before someone get hurt!

Don't sweat the mistake ... we've all made them. Especially when you end up re-writing the equation in a form that's clumsy compared to what we're used to. At least it was on something that wasn't safety critical.

BTW, I know people who would kill to get a 48G (myself included since they don't make them anymore) ... do you think it's fixable? If so, it could put some $$$ in your pocket.

[kennyrayandersen]

I read up on the fix on the internet and evidently it can be done, though some disassembly is required, so I haven't got into it yet. That's the other reason I haven't thrown it away -- I'm hoping to salvage it. I bought the spare one when they announced they were going to quit making them. It was in the blister pack for maybe 8 years until it finally gave up the ghost. It's actually overkill for what I use it for, but once you get used to the RPN, there's no going back.

BTW, took a look at the city you list where you live -- not a lot out that way...

[kennyrayandersen]

OK, so now you made me nervous and I went over to flea-bay and bought a mint-condition HP48G+… just in case the good one goes down and or I can’t fix the lame one! Really it’s more like a blankie than a calculator

[Forrest747]

Ran it through Solidworks, and FEA and I concur and say the 1x2 stacked showed the greater strength.
How ever, just to keep it simple and that its the main frame and not the tounge not worth all the effort, to weld and bolt and such, the body frame.

Now the tounge over-engineer the beast!

An common trailer is the harbor freight trailer is used and looking at the steel beams look like c-channel and not that thick. I would think you could go with 1x2 for the frame and be ok. I went with 2x2 a little more stregth because i am building an off-road trailer. If you are worried just double up where the axel joins your trailer. Just a thought.

[Corwin C]

... but once you get used to the RPN, there's no going back.

Agree 100% ... learned RPN in college out of necessity and now I can't stand to pick up a non-RPN calculator.

BTW, took a look at the city you list where you live -- not a lot out that way...

Yea, it's a quiet place ... population about 150 despite being the county seat. A couple of larger towns within a few miles but they're pretty small too (< 800 population.) A long way to the hardware store (48 miles to HD, which is the closest worth mentioning, a little farther to a decent grocery store).

But, there's lots of stuff around that isn't readily apparent. I'm 45 minutes from Bryce Canyon, 1 hour from Capitol Reef NP, Cedar Breaks NM, and Grand Staircase/Escalante NM, 2 hours from Zions NP, a little farther to Arches NP, Lake Powell, and Canyonlands NP (you'll find those on the map.) What most maps don't show ... beautiful scenery about every direction you turn, all the hiking a person could do in a lifetime, hunting, fishing, river rafting, mountain biking, ATV trails, and camping pretty much in every direction within just a few minutes. During the summer I rarely need an A/C at night and when the days get too hot (and I'm not working) I can be over 10,000' elevation within 30 minutes. In the winter we get enough snow to have some impressive snowmobiling and skiing. The stars shine brightly at night (not much light pollution), the air is fresh and clean (most of the time), I could go on and on and on ...

I think that the reason that I see so many teardrops is that #1. I work right on the highways and #2. I'm right in the middle of some of the biggest and best "playgrounds" in this wonderful nation of ours. If you enjoy the simple life and enjoy the outdoors ... we come pretty close to having the best of everything right here.

[Larwyn]

OK, so now you made me nervous and I went over to flea-bay and bought a mint-condition HP48G+… just in case the good one goes down and or I can’t fix the lame one! Really it’s more like a blankie than a calculator

I have a perfectly working HP 48GX that I would be willing to part with. What are they worth these days?

[eamarquardt]

OK, so now you made me nervous and I went over to flea-bay and bought a mint-condition HP48G+… just in case the good one goes down and or I can’t fix the lame one! Really it’s more like a blankie than a calculator

I have a perfectly working HP 48GX that I would be willing to part with. What are they worth these days?

How can one in kilts work a RPN calculator?

Cheers,

Gus

[Larwyn]

OK, so now you made me nervous and I went over to flea-bay and bought a mint-condition HP48G+… just in case the good one goes down and or I can’t fix the lame one! Really it’s more like a blankie than a calculator

I have a perfectly working HP 48GX that I would be willing to part with. What are they worth these days?

How can one in kilts work a RPN calculator?

Cheers,

Gus

I had to keep up with the engineers on the job somehow. I still have a hard time using a calculator that is not RPN. I guess I learned to think backward "just like an engineer".....

[Cliffmeister2000]

I have a perfectly working HP 48GX that I would be willing to part with. What are they worth these days?

$189 used on Amazon.com.

I have an HP10C, 11C, and 12C. Love them! Bought them all when I worked for an HP dealer in 1983- 84.

[Larwyn]

I have a perfectly working HP 48GX that I would be willing to part with. What are they worth these days?

$189 used on Amazon.com.

I have an HP10C, 11C, and 12C. Love them! Bought them all when I worked for an HP dealer in 1983- 84.

Well, if anybody is in need a 48GX in excellent condition (zipper case is a bit soiled), PM me. I might be able to fix you up.

I also have two each of the User Guides and Quick Start manuals for it, as my first 48GX took a crushing blow from a heavy object falling on it in the back of a service van. I took much better care of the second one......

[Carter]

This thread got way above my old grey head. My job title has the word "engineer" in it, but I'm not.

Jim

[kennyrayandersen]

I think I gave about a hundred and $120 for the G+ in ‘like-new’ condition. I think the GXs go for a bit more as someone posted. The G+ is already more than I need. I use it as a basic calculator with some trig functions thrown in – I probably should have just bought a G and saved a couple more bucks! Anyway, once you’ve had RPN, there’s no going back!

Corwin,
Sounds nice! I’m going to start looking into some land before too long to retire on (I figure I’ll have to work another 18 years ‘till I’m 70 which is OK since I’m planning on living to somewhere just a bit south of 100!). I figure I’ll have to skedaddle out of TX since the property taxes there are a killer for retirees (no income tax though, so while you are working it’s OK). How are the property taxes out that way? It sounds like it would be some pretty good teardrop country (I also MTB and road bike).