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A cage for the Jimmy! Progress pics and worried questions (!) post 18!

Greg72 said:
I'll shoot ya straight on this one..... I don't like the looks of those trapezoid rollbars. :shame:

If it were me, I'd chalk it up to experience and bend-up a couple of new hoops with a more conventional straight-leg design. You're only out the cost of a couple sticks of tube, and odds are that you can cut up those hoops and use at least part of them again for other gussets or intermediate bars.

Spending a lot of time and materials trying to "fix" a poor initial design reminds me of the old expression "you can't polish a turd". :D Not trying to kick a man when he's down....just trying to drive home a point, I think we all know that the correct answer requires going backwards a couple of steps and doing things right, not cobbling more tube onto what's already there.

Don't feel too bad. If I had a dollar for every foot of tube I've wasted, or bent wrong I'd have a big pile of dollars.....



:usaflag:
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colbystephens said:
valid points. :thumb:
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I agree, only problem is, if I want to get it done, I have to go with what I've got. My instructor more than likely won't let me rip all of it out and start over since it is late in the phase (only two weeks of class left) and he feels it's strong enough (He's been telling me that I am too paranoid about design). About my only option would be throwing in the towel completely and pushing the truck out of the shop and onto my trailer which is not really an option either since I've had two classmates help on it and they will be upset at lost points (project not completed= no points toward final grade). (That would put us all back to C's in shop grade whilst we are almost to A's right now.) Then, I would have to just get a fab shop to make me a cage since I don't have any access to all this equipment outside of school.
 
Well in that case, any cage is better than NO cage.... finish the class, get your grade and deal with it later when you have your own tools and aren't being strong-armed by classmates or a teacher to hurry and and finish it.

:usaflag:
 
If you're going to wheel it at all, I'd encourage you to look at some of the rollover pictures on youtube, pirate, etc. and then decide if the cage is strong enough. Getting a "C" seems better than being dead.

If it's for a class, I'd think that making a mistake and learning how to correct it would be worth something. I wouldn't wheel it without doing something about the lower bends.
 
Well, it's getting about to the point where I'm tempted to get it to a "finished" point in class, then just tear it apart and build a different one before I ever wheel it. I definitely do see y'all's points and thank you for the input! I guess i just need to figure out what I am gonna do.
 
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I guess that makes sense. Like Greg said, you can probably use lots of it for gussest and smaller sections after cutting it up.
 
blowedupmotor87 said:
I agree, only problem is, if I want to get it done, I have to go with what I've got. My instructor more than likely won't let me rip all of it out and start over since it is late in the phase (only two weeks of class left) and he feels it's strong enough (He's been telling me that I am too paranoid about design). About my only option would be throwing in the towel completely and pushing the truck out of the shop and onto my trailer which is not really an option either since I've had two classmates help on it and they will be upset at lost points (project not completed= no points toward final grade). (That would put us all back to C's in shop grade whilst we are almost to A's right now.) Then, I would have to just get a fab shop to make me a cage since I don't have any access to all this equipment outside of school.
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that's really odd that the shop teacher would say you are overly concerned about design. isn't the design the only reason you build something structural? it's not like you're building a piece of artwork whose sole purpose is to be some ornamental embellishment on your truck. that's simply a retarded attitude for an instructor to have.

i'm curious, tho, why is it such a big deal as far as time goes to bend up two new hoops? the simple hoop is very quick and easy to bend/design.
 
nolidnoworries said:
Actually.....I saw an episode of Mythbusters where they did polish a turd!:crazy:
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I didn't see that episode but, I bet petrified dinosaur poop would shine up nice!:haha: I have actually seen it for sale at rock shops, I forget the fancy name for it but, it's dino poop.:D

Found some, here ya go!:
http://www.brushybasin.com/Gift_Fossils/PCS/pcs.html
It's some expensive sh**!:rolleyes::haha:

Anyways, yeah, I think I am just going to keep going with the current rollcage design to an end point and tear apart/redesign/rebuild it later. Yeah, it's a possibly a dumb decision but, I need a good grade and school is more expensive than tube. My gf said she'd help pay for a proper rebuild later so...:dunno: might as well just let it go the way it's going and fix it later.
 
colbystephens said:
that's really odd that the shop teacher would say you are overly concerned about design. isn't the design the only reason you build something structural? it's not like you're building a piece of artwork whose sole purpose is to be some ornamental embellishment on your truck. that's simply a retarded attitude for an instructor to have.

i'm curious, tho, why is it such a big deal as far as time goes to bend up two new hoops? the simple hoop is very quick and easy to bend/design.
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Well, I guess I should've phrased that a bit differently. Basically he is saying that I am too concerned about designing it for extremes that the vehicle will never see. He said: it's a rollcage not rocket science, at the rate you're going, you'll never get it done. The problem with replacing the hoops is not the hoops themselves it's that the upper longitudinal bars are already welded to the hoops and the lower ones are tacked and the overhead x is tacked in place, all the foot mounts are drilled and in place, etc. All the bars are measured based off current hoops. Both hoops need re-made so, basically we'd be starting from square one again and it has taken us two weeks to get this far (I am slow to decided how I want things). We have approx. 8 working days left.

Ya know what the real kick in the butt is? I'm the dummy that came up with the hoop design!:doah::doah::doah: I let my easy foot plate placement idea dictate my cage design.:rolleyes: Gonna be a lot of holes to fill to make a new design.

The problem that I am having in convincing everybody that my original design is flawed is the fact that I have no concrete evidence to back up my claims. I'm no engineer and have no clue how to figure out stress points, crush rates, whatever (see, I don't even know how to term stuff, LOL!) it just seems to me that the current design is weak. Every time that I see a hoop in someone's design that it shaped like mine, it always has an X brace and that's just no practical here (if the rear seat is to be inhabitable and the cargo area is to be accesible).
 
blowedupmotor87 said:
Well, I guess I should've phrased that a bit differently. Basically he is saying that I am too concerned about designing it for extremes that the vehicle will never see. He said: it's a rollcage not rocket science, at the rate you're going, you'll never get it done. The problem with replacing the hoops is not the hoops themselves it's that the upper longitudinal bars are already welded to the hoops and the lower ones are tacked and the overhead x is tacked in place, all the foot mounts are drilled and in place, etc. All the bars are measured based off current hoops. Both hoops need re-made so, basically we'd be starting from square one again and it has taken us two weeks to get this far (I am slow to decided how I want things). We have approx. 8 working days left.

Ya know what the real kick in the butt is? I'm the dummy that came up with the hoop design!:doah::doah::doah: I let my easy foot plate placement idea dictate my cage design.:rolleyes: Gonna be a lot of holes to fill to make a new design.

The problem that I am having in convincing everybody that my original design is flawed is the fact that I have no concrete evidence to back up my claims. I'm no engineer and have no clue how to figure out stress points, crush rates, whatever (see, I don't even know how to term stuff, LOL!) it just seems to me that the current design is weak. Every time that I see a hoop in someone's design that it shaped like mine, it always has an X brace and that's just no practical here (if the rear seat is to be inhabitable and the cargo area is to be accesible).
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gotchya.

it's one of those things where it is probably fine for the typical wheeler who is going to go out and the danger is that they might do a side flop or end up upside down - perhaps even a full roll over. since the material you're using is very strong, the truck could easily sit upside down on that cage - no problem. ofcourse, that doesn't take into account the force added by the actual flopping on top. I think it'll keep you alive in most situations you'll be in. :doah:

however, if it's for a truck that might be on cliff edges and in situations where multiple rolls are a possibility, probably not such a good design.
 
easy save, imho

It's not the end of the world in design, not by a long shot. Here's what I'd do, just off the top of my head.

I'd do the red gussets first for sure.. 1/2" plate and they'd be stronger than straight pipe especially against torsion ;)

The blue I'd do for sure, just to stop the square from twisting a bit. Looking at the green now, I'd do those top corner b pillar to back floor probably. Even if you have to bend them outward and gusset them, the big triangle is much more resistant to sliding rollover.

Keep in mind, it's both rollover and the cage stopping the vehicle that collapses them. You need to be able to sit on the cage while sliding on the ground, which is a bit different than just gracefully sitting on it. I agree with the previous assessment that this cage would support the truck 100%. It would probably just twist and bend from the torsion. Gusset all your corners with big ass gussets or double gussets made from notch tube and you're gold from that standpoint.

While I was writing this I had a new idea:

I'd trust that at speed even...

Lots of work, but do-able on your timeline.

Just my 2cents. :D

fittotop.jpg

fittotop_extreme.jpg
 
Cragske-
I understand the gussets, but what is going on in the bottom pic? Looks kind of like a giant A leaning through the cargo area? Extending from the center of the overhead X to the rear hoop? Or, is the A to be vertical, connected at its peak to the center top portion of the rear hoop?
 
More turd polishing!: (bars I have already in green, gussets in lavender (gussets would go around the joints, if a joint occurs at the gusset location), side braces in light blue, B hoop braces in red, rear most hoop braces in white (getting almost the whole rainbow of colors here)):
complicatedcageidea.jpg

Any better? Or still need to scrap the hoops?
 
Good question. I was thinking that by building in the X in the square created on the top you could try to build some lateral strength by putting in the large parts of the "A" from the point created by the X in the top square to the bottom of the back D. After that I got carried away. Lots of opportunity to create triangles that bear the possible directions of force... Not needed really.

Cody's cage is probably a better design, given that you don't want to crash at 65 mph upside down and turning.

I'd probably just stick with the gussets and a single cross piece in the top square now that I look at it again... And I missed a gusset too.

-Craig
 
blowedupmotor87 said:
More turd polishing (bars I have already in green, gussets in lavender, side braces in light blue, B hoop braces in red, rear most hoop braces in white (getting almost the whole rainbow of colors here)):
Any better? Or still need to scrap the hoops?
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Awesome overkill! I'd ride that over a cliff :bow:
 
blowedupmotor87 said:
More turd polishing!: (bars I have already in green, gussets in lavender (gussets would go around the joints, if a joint occurs at the gusset location), side braces in light blue, B hoop braces in red, rear most hoop braces in white (getting almost the whole rainbow of colors here)):
complicatedcageidea.jpg

Any better? Or still need to scrap the hoops?
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woah. i think you need to take a step back and think about that for a second. that looks pretty great on paper, but i think it's definitely overkill. you're looking at adding ALOT of weight, and most of that isn't necessary for the recreational wheeler. those white bars are really going to get old quick if you use your cargo space. consider the bottom upside-down V on the sides (blue) - perhaps you would rather mount it to the wheel well to save some weight. the rear-most red bar seems unnecessary too.

I like the green x brace. i tried to make the bars pass over or close to over the passengers' heads so that if i ended upside down, rocks wouldn't be coming through onto their heads. x's are nice because they make divide up open spaces to prevent large boulders from being inside the cage/cab. on advantage i had in doing it, a luxury you don't have, is that i have a full convertible with a permanent soft top - so i wasn't restricted with height as much as you with the fiberglass top. but i'd encourage you to consider these things in design too.

i like the purple/lavender gusset/braces too. seems like they will make up for any issues the hexagons may have created. i'd trust it in a wheeling rig.

what kind of wheeling do you do? what kinds of risks are you REALLY actually taking? build it for more than you actually need, ofcourse, but the overkill factor at some point just becomes extra weight to prevent you from succeeding at a given obstacle.
 
I like this one...

attachment.php


Those red vertical gussets will address the biggest weakness of the current cage design. What size tubing did you use so far....2" OD?

What would be slick is to get some box 1/8" wall box tubing (Maybe 24" long pieces) that have in internal width that matches your existing cage OD. I'm thinking about something like 2.25" x 4" x 24".

Then, slice off one of the long edges so that the box structure can slide over the undesireable bend in the hoops. The remaining "long" edge of the box tube will now give you a straight vertical look on the inside of those bends. Slide the box structure all the way over the tube until it finally "bottoms out" at the top and bottom against the hoop.

You'll have a bunch of overhang from the square tube once you get that part in place....so carefully cut off the excess so that you're left with a shape that matches the bend profile of the hoop underneath. If you trim it right, it will end up touching the round tube at the highest points, and you'll be able to lay-in a nice weld bead all the way down both sides. If you do a little extra work, you can fishmouth the bottom and top so that there are no gaps at the ends of the new part.

Once you get all the fitment done, and BEFORE you weld them in place....drill a bunch of cool "speed holes" in them, and if you have access to a flarehole die give them some nice flares too! :saweet:

Not only will it add a lot of strength back, it will look killer and you will end up with a bunch of great holes that you can use at mounting points for straps, tie downs, your hi-lift jack, shovels, or bungee cords to lash an extra driveshaft to.

It could be totally awesome, unique and you wouldn't have to cut it all apart later on..... you might even finish on time and get an A+ from your teacher. :thinking:


Hope that all made sense, I can render a sweet MS Paint drawing for you if needed.



:usaflag:
 
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