Roof Raise Steel question

[jake_blue-SKO]

I simply don't know how resilient that fastening method would prove in an accident, IE a decade of road vibration and flexation followed by a rollover in which the loads and stresses suddenly shift to the roof or more accurately laterally against the roof. I think we've all seen the pictures of school buses rolled over and how you'd be hard pressed to tell they even rolled after they've been righted. The same is not true of RVs and motorcoaches. I think in such an event the shock/stress would trigger failure if not in the weld itself than in the surrounding structure and would travel along the weld creating greater failure than a riveted seam. Bolted/riveted fastening can distort and the most stressed points can fail but as the fastening 'gives' it releases the kinetic force of the impact and then at some point the rivets distort but don't fail entirely until the force is completely dissipated. You can end up with a bent bus but not a collapsed bus. At least that's how I'm looking at it. I don't want to see a raised-roof skoolie turned into a convertible in a rollover and I definitely don't want to be in one.

FWIW though, the engineered solution I'm working on would lend itself pretty easily to welding or bolting/riveting. So perhaps there is a value to each method and the end result could be a stronger and more resilient product. If this is something a pro-welder would like to explore with me, I am serious about the idea of raising a roof just to roll it over and prove my solution is comparable in rigidity to the OE design.

 

[Skunky Bus]

See and that's what you would want in a welded component is something that is well-designed and over engineered. I just do not see that level of engineering or welding experience going into most of our skoolie project. Most of the time we're on a shoestring budget!

If it would be worth it there are three identical Internationals sitting at Midwest Transit all with bad engines so they're cheap. If I ship all those down to you would it be worthwhile to do three different methods of roof raise and then we could send them out for crash testing to see how each holds up? personally I would like to know what would be the best method and have it proven before I buy the bus I want to do my actual conversion.

Love this idea! Too bad that our "shoestring budgets" prevent us from doing this.

I'd think that using too many bolts would also cause problems (more holes in the metal). Be it welds or bolts/rivets, I think the more overlap, the better. The book, Find and Convert Your Bus into a Motorhome on a Shoestring, also recommended staggering the frame cuts, so as to avoid creating a "hinge" of weak points along the side.

Just for sh**s and giggles, I just ran a search for "welder" on the job site indeed.com. I couldn't look thoroughly enough to meet the rigors of scientific analysis, but the several ads I examined required welding experience; most of those were three years plus. I liked the one that stated, "If you can NOT pass a drug screen or show up to work everyday on time you need not apply...." Gee, welding while stoned, or rushing to catch up because UR late for work: what could possibly go wrong?

 

[EastCoastCB]

Love this idea! Too bad that our "shoestring budgets" prevent us from doing this.

I'd think that using too many bolts would also cause problems (more holes in the metal). Be it welds or bolts/rivets, I think the more overlap, the better. The book, Find and Convert Your Bus into a Motorhome on a Shoestring, also recommended staggering the frame cuts, so as to avoid creating a "hinge" of weak points along the side.

Just for sh**s and giggles, I just ran a search for "welder" on the job site indeed.com. I couldn't look thoroughly enough to meet the rigors of scientific analysis, but the several ads I examined required welding experience; most of those were three years plus. I liked the one that stated, "If you can NOT pass a drug screen or show up to work everyday on time you need not apply...." Gee, welding while stoned, or rushing to catch up because UR late for work: what could possibly go wrong?

I've never met too many welders who were bad to be honest. Once one learns the proper skills its not too hard to weld- other than the heat and awkward positions one has to sometimes stand in.
I know PLENTY of stoner dudes who weld. The ones that ad is most likely referring to are the ever growing number of pain pill addicts. We had a LOT of those. One fell asleep WHILE welding one day and was on the floor cold with his finger stuck on the trigger and about twenty feet of wire hangin out. I was in the next bay.

 

[jake_blue-SKO]

LOL thanks for the laugh

 

[aaronsb]

I'd make a wager that every single one of the roof raise projects you see on the skoolie site and elsewhere use techniques similar to that of the original manufacture. That is to say, sheet metal skin with clamping force fasteners at regular intervals.

The structural component, the ribs, are extended in a method generally accepted for building up structural components when made from steel, which is to say welding layers of structural reinforcement to a core.

If you prefer to retain a one-piece-virgin-part approach, then you'll be replacing each of those ribs with a new one, which would necessitate rebuilding the entire coach from scratch.

I am curious to know how you plan on constructing a better mousetrap here. The two generally accepted methods of constructing vehicles that I can think of are either:

1) unibody design - full presentation shaped components fused together with adhesive, spotwelds, or a combination thereof to form a resilient engineered unit

2) sheet on frame - structural subframe designed to carry compressive loads, with sheet fastened or adhered to resist shear and tension loads.

These two approaches comprise about every vehicle I can think of driving by when I look out the window.

Other methods, like a monocoque seem neat and exotic, but expensive to construct.

I simply don't know how resilient that fastening method would prove in an accident, IE a decade of road vibration and flexation followed by a rollover in which the loads and stresses suddenly shift to the roof or more accurately laterally against the roof. I think we've all seen the pictures of school buses rolled over and how you'd be hard pressed to tell they even rolled after they've been righted. The same is not true of RVs and motorcoaches. I think in such an event the shock/stress would trigger failure if not in the weld itself than in the surrounding structure and would travel along the weld creating greater failure than a riveted seam. Bolted/riveted fastening can distort and the most stressed points can fail but as the fastening 'gives' it releases the kinetic force of the impact and then at some point the rivets distort but don't fail entirely until the force is completely dissipated. You can end up with a bent bus but not a collapsed bus. At least that's how I'm looking at it. I don't want to see a raised-roof skoolie turned into a convertible in a rollover and I definitely don't want to be in one.

FWIW though, the engineered solution I'm working on would lend itself pretty easily to welding or bolting/riveting. So perhaps there is a value to each method and the end result could be a stronger and more resilient product. If this is something a pro-welder would like to explore with me, I am serious about the idea of raising a roof just to roll it over and prove my solution is comparable in rigidity to the OE design.

 

[jake_blue-SKO]

Building an entirely new body does seem a little bit like just building your own RV from the frame up and you end up throwing away all that material instead of recycling it. Most of our approaches probably end up with one piece becoming 5 if you figure cutting somewhere in the middle of the sidewall and splicing in a piece to extend its height. I don't have detailed schematics yet but my rough outline would probably illustrate my idea better than trying to explain it in text... if I could just figure out how to upload pictures here. It would consist of a structure more substantial than a hat channel but not so extensive as a whole new body from scratch.

 

[The Rockwood Colony]

I over lapped 12 inches on both ends.

I raised my roof 24 inches. This made my splice pieces 48 inches long, making best use of the 4x8 sheets of steel we sheered to form the ribs from with no waste.

I would not do less, you want to spread to connection over as large area as you can.

Mine were custom formed 14ga ribs made to the same shape as the original ribs.

I was the first one I ever seen to do the custom formed ribs. It's the best and strongest method that can be used.

I was also the first to use scaffold to lift the roof. I found it vary safe, simple and easy.

More can be seen here in my latest build thread.

http://www.skoolie.net/forums/f11/the-four-season-prime-10138.html

Nat

Hey Nat! Is there a video somewhere you can recommend watching to help me visualize and mimic the way you accomplished your roof raise? I understand things much more when I have a visual. I would really appreciate a step by step resource recommendation! Thanks man!!!

 

[Rusty-SKO]

Bluebird did my roof raise for the Coachbuilder. They butt welded the channel pieces in the ribs. seam visible under top 2x4.

I wouldn't hesitate with lapped channel that is properly riveted. It'd be plenty strong. Much strength added from riveted skin.

I do not recommend rolling any bus over as they are difficult to put upright.