roof rack materials

[sasaholic]

ok im going to weld up a roof rack to go ontop my canopy. question is will 1 inch .090wall round tube strong enough to hold me and my girlfriend(combined weight about 275)? it will have plenty of slats or tube(whatever you want to call em) for the base/floor, but im not real sure if i will be ok or not. i know that defender racks are only made out of 16 guage which is like .066 i think, but then again im not sure how strong they are. oh ya its going to be a 4x6.5 rack, well basket actually.

 

[ExpoMike]

Yes, that will be more then enough. Most rack are in the .060 range and 3/4" diameter. I know I did a roll bar in a dune buggy that was .090, 1.5".

More important is the design and mount. Also quality of the fitting and welding. Don't exceed your roof/gutter capacity and I believe in more mounting points then less. It helps to distribute the load better.

Post up pics when you start building. I have a design in mind for mine and will be very cool but I am keeping it a secret until I have done it. I don't think anyone has done my idea before. hehehe

 

[sasaholic]

any idea how much deflection a .090 1inch tube thats 4 feet long would have. and im going to drill straight into the canopy right where the top meets the side, because thats the strongest section, and i plan 3 mounts per side and one in the front and one in the back centers.

 

[24HOURSOFNEVADA]

Tube composition matters a lot when your discussing strength, i.e. HREW, DOM, or CHROMOLLY. Unless I missed it, you didn't state your material, only the size...

 

[ExpoMike]

My guess he will be using HREW since it's most common and cheapest.

As far as deflection, I am not quite sure how you are mounting it. Are you laying the tubing against the roof and mounting it directly to it?

Take a look at some of the other rack on the market and that should give you an idea of how to design it. If you place all 275 lbs. at on point midway on the 4' span, you will get maybe an 1" or so of deflection but that would be a static load. If you are talking about this same weight on one point but driving down the road where you will have dynamic loads, that may be too much.

Now if you are talking about 275 lbs spread over 10 4' cross rails, then your loading per bar is greatly lowered. It's really going to come down to the design of the rack and how you disperse the load across it. You might want to do a quick drawing and post it up.

 

[chet]

for the amount you would want to put on a Canopy (300 lbs?) some electrical conduit would probably work. Or something like 3/4" sch. 40 pipe (.113" wall)

 

[sasaholic]

basically i want to copy defenders design, but as 1 or 2 peices of tube long ways down the floor of the rack. and ill be using hrew tube. im just getting into playing with metal, ive been a hardcore woodshop guy, but that doesnt come in as handy in the 4 wheeling world as metal fab does. i am correct in thinking that .090 hrew tube is stronger that electrical conduit that is say schedule 40 right? i want to keep the weight of the rack down as much as possible

http://defenderrack.com/products.asp?id=24

 

[rickc]

If you can weld aluminum you may want to consider making a rack with signicantly less weight for the same strength. Here are some details of my rack. It's 9' long by 7' wide and I can easily put it on and off by myself.

Note the load distribution; six 10cm wide feet on each side.

 

[ExpoMike]

If you can weld aluminum you may want to consider making a rack with signicantly less weight for the same strength. Here are some details of my rack. It's 9' long by 7' wide and I can easily put it on and off by myself.

Note the load distribution; six 10cm wide feet on each side.

Not sure if I thought I would ever say this to another guy but.... Nice Rack! :elkgrin:

 

[KEENO]

Bosch Rexroth Extruded Aluminum

I'm also planning to build a 3' x 6' Roof Rack for the cab of my Standard Cab Pick-up to hold the 35" Spare and a 24" x 36" Box that will hold the grille & stuff. My first choice was 1" square Aluminum Tubing and TIG Weld it all together, but after stumbling over commercially available Extruded Aluminum that is mechanically bolted together.... I'm considering making it out of Bosch Rexroth Extruded Aluminum.

Check out the possibilities with this material: Light, extremely strong & rigid being and extrusion!


http://www.boschrexroth.com/country_units/america/united_states/en/products/brl/product_overview1/mge/index.jsp

It's like giant Tinker Toys.... Somewhat spendy tho.
KEENO

 

[ExpoMike]

That's very cool stuff! May have to look more into that. Thanks for the link and a different idea for material.

 

[JamesDowning]

We use that extruded aluminum for test fixtures where I work. It's very rigid, but you are right, a bit expensive. The benefit would be the ability to mount just about anything at any location on the extrusions. They can be a little tricky to work with though.

 

[KEENO]

We also use it in the workplace (Automotive) and have complete Conveyor Lines made out to the stuff. Extremely Durable & Strong. I was a bit skeptical about the mechanical fastening, but Maintenance states, they've never had any issues.

We have some scrap laying around from an old conveyor that might become donor stock for my Roof Rack Project.

Bosch even makes 'plastic strips' that fit in the grooves to give a finished appearance (completley fills in the gap in choice of color)
KEENO

 

[rickc]

Keeno:
Very cool tubing. The external T slots would have multiple uses. Looks expensive.

 

[S.Limited]

I would question the durability. I have seen many similar design running boards corrode right through due to road salt. Snow and water would just sit in all those channels and do its magic.

For internal use it would be great though. Custom campers or custom SUV interiors.