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Roll cage advice


HoSS

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A question for you proper engineers, structural types...

So, i was pondering doing something similar to this on my Volvo C303.

gecko_c303_zpsauud8rl7.jpg

But on mine i have rigged the cab to tilt for access to the engine, and so would have to be able to disconnect the cage over the cab.

Firstly its worth saying that mine will not be for competition or extreme use, but rather for overland touring.

Initially i though about male-female spigot joints with retaining pins through. But on reflection i could perhap make strong tubular hinges on those 4 legs which sit on the bumper, and have bolt flanges on the top to the main cage.

Comments, criticism, ideas welcome...

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What are you trying to protect? The driver and passenger incase it rolls over which is a hugely unlikely event in your application and would be considered a catastrophic failure by the driver?

If so why not just do a cage that forms a cell around the driver and passenger that tilts with the cab? Bring it under the seats so they (and the belts) fasten to it and over your head to stop the roof folding in and you have pretty much all you need? OK the truck would be damaged but it's unlikely you'll roll and if you do it'll probably just lay on it's side and end up with a few dents, broken windows and a bit of spilt milk but it'll save all that work and top heavy weight to lug around.

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I guess, some driver passenger protection in the event of a roll (unlikely but possible in my use), or crash. And general bump protection from off-road use.

I didn't really want to put it inside the cab, as that would greatly impact space.

Also it would double as roof rack on top of the cab.

By the way what grade, size of tube is recommended? What is acceptable to de-rate to for non-comp use?

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For the basic "not all die in a crash" spec a sturdy hoop behind the cab would be easiest, although that doesn't protect the cab from trees - possibly some simple & minimal brush-bars fixed to the cab would do for that.

You need to think carefully about realistic use cases Vs weight + complexity, proper comp spec cages are designed for the "barrel roll at 100mph into a tree" scenario, and some people aim for "...and keep driving as if nothing happened" after that, but that's neither useful nor practical for your truck.

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I am vapour building similar for my unimog, having a tube coming out of the scuttle up the a pillar then backwards along the roof before bending across to the other side and back down, two vertical supports at the rear, a top windscreen bar and then tied into the cab floor 'chassis'

Should allow the cab the move and tilt but keep light branches off the bodywork and should not he worst happen it keeps the cab a reasonable shape (hopefully :) )

I don't really like the look of the climbing frame truck trial look if I'm not going to be testing it.

Will.

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I had a clarke bender, I never used it to make a full cage but used it to make add on bits like harness mounts, rock sliders, body protection etc. It could do it but it was a lot of work getting the formers to fit right, I ended up packing them with lead flashing and I'm not sure they were the right radius for a competition cage? I found it was easier to bend a thicker tube than a thinner tube as the thinner stuff used to dent, kink or ripple either on the former side or the roller bits on the top. I guess it comes down to the elongation of the tube as well as it's strength, hardness, thickness and diameter. Generally I built from what I acquired so it was never the idea material for the job, I guess if your buying you might be able to buy a pipe that fits the bender? I also managed to bend some box on it. I did find a good guide to using one for a cage on a forum or youtube but I can't remember where now...

Someone offered me some cash for it so I ended up selling it telling myself I'd buy a better one but I never managed to justify the cost so I kinda regret it as it was a handy thing to have lying around if you had the patience for it.

You could look into hiring / borrowing one I guess, you might be able to get a draw bender rather than a push bender this way?

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Well i'm not averse to investing in tools, they last a lifetime after all.

I have the whole body cage to make as in the picture above, and imagine some tinkering to get it right.

I will investigate this bend-tec / P&P. Although where i live, its not easy to find these companies and imagine shipping would equal the cost of a bender.

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Still looking for JD2s on ebay etc...

But what do we think of this kind of bender?

http://www.ebay.co.uk/itm/1-1-2-Tube-Bender-Pipe-Bender-by-Affordable-Bender-/151500715307?hash=item234625752b:g:pGkAAOSwnDxUdPQD

They sell the dies separately and i could make that frame up.

p.s. could someone tell me what tube spec i should use? Dia, wall, material spec?

Again not comp use, but best strength to weight and ease of bending.

Actually, i could do the same with the JD bender. Buy their die set, and make the rest myself. This keeps the budget and shipping down. Any kind souls with a JD like to take some pics and note down key dimensions?

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Having done a bit of research here, i think i will look out for a JD2 bender.

Good choice! I have one - and added a hydraulic ram (from a digger) which makes the whole thing much easier.

My personal choice was to buy 1 3/4" and 1" dies - and use 1 3/4" x 3.25mm wall thickness for most structural members and 2.03mm for non structural bits.

There is a thread here: http://forums.lr4x4.com/index.php?showtopic=4229

However, it always seems to turn into an argument when people discuss it - and there is no 'correct' answer as there are so many variables. In particular, the design of the cage!

Si

P.S. Get yourself a copy of BendTech software - it will pay for itself in the amount of tube you don't waste! You calibrate the software to your bender and it calculates the bend allowance, bend angles & rotation. It's brilliant! CAD for Cages in effect.

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Another vote for the jd2 but if your spending that sort of money have a look at the model 32 and seriously consider the hydro conversions.

I set mine up with a big ram but when all was said and done it took up too much space so I splashed out and bought the power team ram and hydro adapter for it. You dont need the ram as it's quite costly but you can buy the adapter and have a thread cut into a normal ram which returns on external springs.

The ratchet mechanism is good but the bender needs bolting to the floor in a very open space (especially for big hoops) and a fair amount of muscle to get it moving.

This guy is either bending old deckchairs or he's the hulk in disguise

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Hi HoSS

Here in Denmark the rules dictate CDS 45x2,5 mm. tube.

We are bending those in a JD2, it´s quite doable and you save a trip to the gym :glare:.

For the amount of tube you need to bend for one cage, I wouldn´t bother with hydraulics.

​

A question for other using the JD2.

How do you get along fixing the tube to the bender ? I find that I either have to tighten the bolt so much that the tube is marked by the bolt or as I do now, place some sanding paper between the tube and the U-bracket.

For those of you who use the ram-solution, how do you make precise bends ?

Hope the hi-jack is ok.

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For those of you who use the ram-solution, how do you make precise bends ?

Exactly the same as without the Hydraulics. Bend a bit, back up a tiny bit to release the pressure in the ram to see how much it springs back. Repeat until you have the bend you want. Set the stop at that point (the stop has a switch that switches off the pump). It gave very repeatable results.

The ram is plumbed through a Lever spool valve which gives a degree of proportional control - so it's easy to apply a small amount of force, or a lot.

The heaviest tube I've bent on it is 1 3/4" x 9.53 wall - and you could hear the pump complaining a bit but it did it.

Si

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How do you get along fixing the tube to the bender ? I find that I either have to tighten the bolt so much that the tube is marked by the bolt or as I do now, place some sanding paper between the tube and the U-bracket.

I polished the end of the bolt which works ok but I think a piece of steel formed around the tube would be a bit better

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Ok I admit it, I´m no wizkid on hydraulics, so didn´t think about the stopindicator, but it certainly makes sence ^_^.

Si, that sounds unbelievable to me, but probably true. I just bend some tubes today in 38x2,5 mm. nothing demanding. Tightened the tube to the U-bracket using a spanner, and quite firmly. The tube moved 3-4 mm. as I started bending it ?

​

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  • 3 weeks later...

Hmm i'm revisiting the idea of designing the cage in CAD and getting components made up. It may work out more cost effective that finding a decent bender.

Although looking at bend-tech and as i would need the PRO version, i find 295 a bit hefty for a one off use. I wish there was a home use version.. I suppose the lower EZ3D version could be used to design single parts... advice from users appreciated.

Any other options? I do have AutoCAD suite at work which i use for 2D designs, but i'm not a 3D expert.

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If your getting the parts made up you don't need bend tech, it's up to the tube bender to work all that out based on their equipment. Just draw up the shapes you want as a line drawing on autocad / fag packey and specify the tube you want using and the rads. If they're a professional cage maker you could even say tube and rads to specifications laid down by msa and see what they propose.

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