custom bed rack

Planning to build a bed rack but still undecided whether to use aluminum or steel material. I have an old headache rack that I bought from 4WheelOnline and I'm planning to copy its thickness. Or maybe I should go with 1.5" square tubing with a .120 wall steel?

The rack will be the same height as the cab of my truck, so it's fairly large. Aluminum can be lighter than steel but it will also depend on the load-bearing requirements of the rack. Is it good to design the rack in a way that the load-bearing portions are made up using trusses of smaller dimension tubing? With that idea, more welding and fabrication should be done to the project.

Mchiz said:

Is it good to design the rack in a way that the load-bearing portions are made up using trusses of smaller dimension tubing?

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Not if it's not needed. 1) What are the expected loads? 2) What constraints do you have on finished rack weight, and finished rack cost? Given 1 and 2, access to a catalog of standard tube sizes, and a basic knowledge of cookbook strength of materials (mechanical engineering 101), we can usually choose standard tube sizes with adequate strength and stiffness for the task. But I'm getting ahead of myself...

How do you intend to fasten the rack to the truck? What do you plan to carry on your rack? How will you get it up there and back off again? Do you intend to attach tools or side loads to the rack support uprights? How will you secure loads to the rack? Besides static load dead-weight, what sort of dynamic loads (from driving the truck) do you expect? You planning on rolling the truck offroad, or sinking it in mud-pit, or is this for a hard-surface driver only? Is this rack an actual headache rack, responsible for keeping the load from smashing the back of your head open, or is it just responsible for keeping a bunch of conduit and PVC pipe from cluttering up the bed of the truck?

After you come up with answers to some of those questions, then is the time to worry about whether it should be aluminum or steel, tube or truss, gingerbread or fretwork.

SFriedberg has just about covered it, but I'm gonna barge in anyway

Every rack I've ever built has had unforeseen problems, despite best efforts at design. Now I just start by welding something up and modify as needed. It's just a tool after all, a tool that's gonna get beat on and scratched and dented, though it's often viewed as an extension of the truck's manhood or an entry in an imaginary design competition.

Most of the problems have to do with resonance. Varies with load, speed, tiedowns. Really hard to predict.

The last rack I bid on (didn't get it, thank Dog) was built out of stainless square tube, rugged as hell, built to carry timbers, godawful expensive, howls like a banshee going down the road. The owners hate it.

IMHO, best to incorporate possibilities of stiffening/weakening in the design. And possibilities for tiedowns, chain tighteners, bunjies, ratchet straps and ropes. They'll be used at one time or another. And paint after testing.....

Mchiz said:

Planning to build a bed rack but still undecided whether to use aluminum or steel material. I have an old headache rack that I bought from 4WheelOnline and I'm planning to copy its thickness. Or maybe I should go with 1.5" square tubing with a .120 wall steel?

The rack will be the same height as the cab of my truck, so it's fairly large. Aluminum can be lighter than steel but it will also depend on the load-bearing requirements of the rack. Is it good to design the rack in a way that the load-bearing portions are made up using trusses of smaller dimension tubing? With that idea, more welding and fabrication should be done to the project.

Click to expand...

Shirley there is a forum more devoted to the design & build of these things...
I built one 30 years ago, and know of people that make them for a living.
You need a forum where all those little ideas come together.

EDIT: At least we could post some of our little features here.
Mine was for an 8' bed f-150 supercab, and I ran it over the whole cab.
I used chain link fence over the cab. Welded and pulled, welded and pulled.
It ended up nice and tite, no problems whatsoever. I used mostly 2" x 2" x 18" angle,
and the diagonals (looked like a bar joist) I took 1/2" sq. and twisted them.

Local shop makes them with 2" sq. alum. tube, simply pastes them together.
Google Maps
No website for the shop.

With todays thinner sheetmetal, I would look at making the uprights go inside the box, down to the floor.

Make ladder hooks on the sides.