Truck Flatbed steel size

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I'm revisiting making a flatbed for my F250 pickup again.  Box cross members are rotten and wheel wells are on their way out too.  I want to keep it as light weight as possible.  What would be the best choice for framework material and how small could I get on wall thickness of steel?  I was thinking I could get by using 1/8" wall tube for cross members.  Too thin?
Reply:Originally Posted by Nick Kent ...What would be the best choice for framework material and how small could I get on wall thickness of steel?  I was thinking I could get by using 1/8" wall tube for cross members.  Too thin?
Reply:Well, I know my stock pickup bed uses cross members that are less than 1/8".  Again this is a SRW 3/4 ton truck I have a 2000 lbs payload tops.  C channel would probably rot out slower than tube would.  I guess if I brace it enough 1/8" wall would be more than enough.
Reply:The stock pickup beds appear to use formed sheet metal crossmembers similar to the 'hat' channel used to support metal roof decking.  Probly about 16 or 18 ga.   Most truck flatbeds I've seen though use alot thicker sections for the crossmembers.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:If it were me and weight was an issue i would go aluminum and it looks cool to. Should not rot out anytime soon like ever really. ive built a couple 4 wheeler beds out of it and its lighter than the plastic bed and all.
Reply:Biggest mistake I see people make, building truck beds, is making them too heavy.  1/8" diamond plate is more than heavy enough, especially formed with either a 4" or 6" rub rail along the sides.   Crossmembers, just use 1/8" formed 4" c-sections.   Check with your steel supplier,,,,   many have the crossmembers already in stock.  Real channel iron, either 3" or 4", just for the runners on top of the frame.Even being in the business, just for a generic flatbed, I'd seriously consider buying one of the manufactured ones, coming out of Oklahoma or Arkansas.   The trailer dealers sell them,,,,   I know up to a couple years ago, you could buy one cheaper complete than even just buying the steel for building yourself.If you build yourself, especially if you are in a cold country area, with salts etc. spread on the road, I'd stay away from any kind of tubing underneath, the tubing always rots out faster than a simple c-section that you can wash thoroughly.
Reply:I'd love to go aluminum, but $$$ is an issue.  Just thinking about the cheapest route.  Truck isn't going to be with me for a whole lot longer anyway.  4-5 years more max.  I've priced out steel beds, and yeah if I built a comparable bed I wouldn't be able to do it for as cheap as a manufactured one.  BUT, I'm really thinking about pushing my limit with the wall thickness of the steel.  Even go with a wood bed.  Plus, I could Mig the whole thing together with steel instead of tigging it which would take forever.  It really would be a fun project to screw up.
Reply:mark8310 is absolutely right about over-building these. I have only done one, and the smallest thing I used was 3" channel. It was super strong, but wasteful,and heavier than it needed to be. I won't make that mistake again.