First-gen utility bed design.

[Combat Chuck]

So, I've been itching to design my own utility bed for my truck since the day she rolled home, and thanks to the magic of Sketchup, I can make these ideas come to life, and ask for feedback on them.

The idea is based on a simple flatbed in-line with the current floor of my bed, with a U-shaped series of shelved boxes on it. The flatbed would be solid steel, but the boxes would be framed out in steel, and "skinned" with fiber-reinforced plastic.
Instead of individual doors for smaller individual compartments, there would be two primary boxes with swingout doors on the sides, and modular shelving, so each compartment can be rearranged as-needed.
A headache bar overhead by the back of the cab would double as an auxiliary light/signal bar, and as roll protection. It would be thick steel rectangular tubing, and fully anchored into the frame of the flatbed.
Finally, a stoutly-framed tonneau cover will cap the unit. The reason for the overkill build would be so a rack, or even a small RTT can be parked on it as-needed.

so, here was my first rough idea:

Ultimately, it was too complex, and potentially heavy to make it work.

I spent some time revising it, and also getting to be more familiar with Sketchup, and here is my next draft:

I went for a sleeker, simpler design without boxed fenders, and with less hinges and latches to add weight and complications

Here's another shot:

Here it is opened up:

I've opted to have the tonneau begin just after the headache bar, to prevent issues with the bar and cover interacting with each other, and causing issues. That also left room between the legs of the bar for a small compartment for storage of emergency staples, like tools, spares, rope, MRE's etc.

I opted to make the side-doors swing out in the drawing, but I'm reconsidering. The space requirement of swinging doors would be detrimental in tight spaces.

A final teaser.

I hope to revise these drawings to show more of my ideas, and to develop a "skeletal" version that shows the framing that would be done.

thanks for reading.

 

[Bogo]

If you have the ability to fold metal long pieces of sheet metal, look into using hat channels glued in place under the bed floor for supporting it. A bunch of them under a sheet of metal can stiffen it up allot. That will allow the bed floor to be made from a thinner sheet and thus weigh less. Similar can be done with the box bottoms, tops, sides, and corners.

In all cases when I'm talking about gluing I'm referring to auto body glues. With enough overlap, and proper surface preparation they can be as strong as a weld with no heat deformation issues. Very high bond strength tapes can be used instead of glues.

Drawings:
#1) Typical hat channel on a sheet of metal.
#2) A pair of "hat" channels bracing a box corner.

 

[rusty_tlc]

You might want to modify the back, the departure angle looks like it wouldn't work on the trail very well.

I'd make the side doors either open up or fold down. The swing out idea might be a problem in a lot of situations. Perhaps the bottom half could fold down to form a table and the top half fold up to form a "roof".

A long compartment in the front that went across the entire bed would come in handy for stuff like axles, Hi-Lift, fishing poles, etc.

You might also plan for a fuel cell and water tank in the center section with a filler tubes on the outside.

 

[Combat Chuck]

You might want to modify the back, the departure angle looks like it wouldn't work on the trail very well.

Good point. I'm still reworking the ideas on that, but I'm much happier now than with the older orange one. I tried to eliminate overhang as much as possible, but I'll look at it further.

I'd make the side doors either open up or fold down. The swing out idea might be a problem in a lot of situations. Perhaps the bottom half could fold down to form a table and the top half fold up to form a "roof".

Definitely. I realized the barn-door idea was a bad one as I just finished posting it. I think a drop-down tailgate style would be ideal, because it creates a work surface.
The Table-roof idea's not bad either, maybe I could make one side swing up, and the other side removable/relocatable, and arrange for that.

A long compartment in the front that went across the entire bed would come in handy for stuff like axles, Hi-Lift, fishing poles, etc.

I was thinking about making a subdivision inside the main hold, about 3" off the bed level, and epoxying in PVC pipes in there for axle "sheaths", or mounting the "sheaths" under the bed, along the frame. That way, I could store them in their own individual container packed with grease to protect from oxidation/rattle damage.
I was thinking about a bolt-on solution for a highlift on one door, and a bolt-on system on the other for a shovel and axe.

You might also plan for a fuel cell and water tank in the center section with a filler tubes on the outside.

I was wondering about that, too. Maybe trying to squeeze a small, flatter, tank between the frame rails of the "saddle" just after the cab, or one of those bed-mounted aux. tanks I see in ag-type trucks around here.

 

[Combat Chuck]

If you have the ability to fold metal long pieces of sheet metal, look into using hat channels glued in place under the bed floor for supporting it. A bunch of them under a sheet of metal can stiffen it up allot. That will allow the bed floor to be made from a thinner sheet and thus weigh less. Similar can be done with the box bottoms, tops, sides, and corners.

In all cases when I'm talking about gluing I'm referring to auto body glues. With enough overlap, and proper surface preparation they can be as strong as a weld with no heat deformation issues. Very high bond strength tapes can be used instead of glues.

Drawings:
#1) Typical hat channel on a sheet of metal.
#2) A pair of "hat" channels bracing a box corner.

That may be the way to do it for the bed.
Heck, those look just like the joints Toyota uses to reinforce the bed in a cruiser.

I have no press, though, and no metalworking skills, so I'd probably farm the structure out to whomever is the most skilled, and then skin it at home with FRP, which is my preference because it's cheap, and easy to replace.

 

[Bogo]

That may be the way to do it for the bed.
Heck, those look just like the joints Toyota uses to reinforce the bed in a cruiser.

They are. In fact they are simple forms of what is used in any unibody.

I have no press, though, and no metalworking skills, so I'd probably farm the structure out to whomever is the most skilled, and then skin it at home with FRP, which is my preference because it's cheap, and easy to replace.

Easiest to replace is glued in metal or FRP sheet. Use a heat gun to soften the glue and pry apart. It is a little harder to remove a composite panel as they are stiffer. My issue with glue joints is they need area to work and any forces on the parts must distribute that force over the whole width of the joint. A joint where the bed floor sheet metal is on top of the frame would work as any down force on the floor sheet would be pushing the glue joint together. On the other hand, if the bed floor sheet was glued under a lip, when pressure is placed on it, the glue joint at the edge could separate. As continued pressure occurs the failure could progress and cause total joint failure. In the attached image at the end I show some glue joints. Red is sheet metal floor, black is the glue, and fuchsia is the frame. #1 works for loads from the top. #2, loads from the top will peal the joint, but loads from the bottom won't. #3, any loads will tend to peal the joint.

For the Micro-RV I was looking at farming out all the cutting and bending of the metal bits. Basically get a kit of parts, then glue and weld them together. The overall frame would be welded up from 2" x 2" x 1/8" extruded aluminum angle stock, and 1/8" thick AL plate bent to form curved angle stock. The 3 dimensionally bent corners would be formed from 1/8" plate. Could be done on a press with inner and outer forms to set the shape or by hand hammering over a ball anvil. The floor, sides of the wheel wells, and tops of the wheel wells would all be AL-foam-AL composite panels braced with hat channels where additional strength and stiffness is needed. As an example there would be a set of hat channels under the floor to transfer the load from the floor to the truck frame. After looking for pre made composite panels I figured it was best if I just made my own using vacuum bagging. That way I could use stiffer than usually available core foams.


The smooth sheets used on the sides of semi trailers are usually all FRP, or AL-FRP-AL composites. There are places that sell them, and it may be possible the get pieces from a semi trailer repair place. Shipping can be an issue as some are to stiff to ship rolled up.

A hat channel corner using a 1/8" plate of AL bent to make the corner. This s something I came up with before engineering analysis told me I didn't need the hat channels if I was using AL-foam-AL composite panels. A simple 2"x2"x1/8" extruded AL angle glued to the inside corner provided enough strength and stiffness. See the second image. If only AL skins are used, then the hat channels were needed.

 

[Combat Chuck]

I've decided to scale this back to something within the bounds of my budget, skills, and materials.

Instead of building an entire bed, I've settled on an insert that I can just run in my stock bed, with storage boxes along the sides and over the fenders, two drawers underneath, and a locking cargo bay so I have a secure place for my pack when I leave for backpacking trips.
I'll end up just making it out of 2X4 and ply, and sealing it up heavily with UV resistant deck paint and bed liner where necessary.

Here are the pictures:

This is it closed up. I've decided that it should be small enough to allow for a truck bed toolbox for my emergency gear, (eventual) compressor, and tools. Having the smaller separate box would make it easier for me to reach my equipment without having to pull open the main tonneau.

Popped open to show the tool boxes and layout. I wanted it to be kept simple:

And pulled out to show the drawers underneath:

Rusty, Bogo, I really value your input on this board, and have appreciated your previous comments!
Thanks!


Here are my most recent drawings

 

[rusty_tlc]

I like the new approach. You might consider a bought tonneau cover, either hard or soft, it will be much lighter and probably look better than anything you can build out of ply and 2X4. The interior boxes could be built out of 1/2" ply alone.

 

[Bogo]

I second Rusty's comment as well as I'll mention that wood on a vehicle is hard to get to stay waterproof. If you covered the wood with fiberglass resin, it would have a better chance of staying waterproof.

 

[Combat Chuck]

I like the new approach. You might consider a bought tonneau cover, either hard or soft, it will be much lighter and probably look better than anything you can build out of ply and 2X4. The interior boxes could be built out of 1/2" ply alone.

Makes sense.
I'm looking for a tonneau, but it's hard to scrounge one up for an older truck!
If I could get away with it, I'd even swap in a second-gen bed to accommodate.

I second Rusty's comment as well as I'll mention that wood on a vehicle is hard to get to stay waterproof. If you covered the wood with fiberglass resin, it would have a better chance of staying waterproof.

That is a great idea.
I'm sure our local marine supply shop will have fiberglassing resin a-plenty.

 

[rusty_tlc]

Back before the hard tonneau covers were around one of the guys I worked with had a sheet metal shop make a cover for his truck bed. I'm not sure how it would compare to a fiberglass one in weight or cost but it might be worth looking into.

It would also give you more options in design. Say a double sided lid with a hinge down the middle, or a 40/60 split front to rear.

 

[Combat Chuck]

Back before the hard tonneau covers were around one of the guys I worked with had a sheet metal shop make a cover for his truck bed. I'm not sure how it would compare to a fiberglass one in weight or cost but it might be worth looking into.

It would also give you more options in design. Say a double sided lid with a hinge down the middle, or a 40/60 split front to rear.

that's an idea, too.
I've just begun to contemplate a softopper, too.

 

[Bogo]

We use the soft toppers on the farm. I would not count them as secure at all. All they provide is out of sight, out of mind type security. What they are really good for is keeping the snow and rain mostly out of the pickup bed. You need to clear snow off them, and retention them if they start to get loose. The looser they are, the more water will pool on them. It is particularly bad in winter if it freeze thaws a bunch. The snow will hold the water, and increased weight will stretch the fabric, and bend the support bows.

 

[Combat Chuck]

I hadn't really thought about the stretching, but it makes sense.
If I did go ST, it would not be daily, but as-needed for journeys. I'm partial to the notion of it acting as a tent instead of setting one up, or running an RTT.

Maybe I could Hybridize these ideas, and have a metal tonneau built that sits inside the lip of the truck bed, and then the ST over it. I can fold back the top to pop the hatch, and set up an air mattress on the tonneau. That way everything that needs to be secure will be, but I'd still have a nice roof overhead.

Using wise choices with my materials, I could squeeze a pretty lightweight setup out of this that would be really effective.

 

[Combat Chuck]

I think I've finally come up with a design I'm the most happy with.

Rusty's earlier comment:

Back before the hard tonneau covers were around one of the guys I worked with had a sheet metal shop make a cover for his truck bed. I'm not sure how it would compare to a fiberglass one in weight or cost but it might be worth looking into.

It would also give you more options in design. Say a double sided lid with a hinge down the middle, or a 40/60 split front to rear.

got me thinking about building the cover out of sheet metal again, and the spit design seemed to most practical.
Basically, with a six foot bed, I'd have one one-foot door, a two-foot fixed middle section, and a three-foot door. This would reduce the lifting weight of each tonneau section to the least possible, and make the opening radius of the hatches as minimal as possible to allow for easy access with the soft top up.

I've decided to run with the soft top idea as a back country tent substitute, but rely on the secure, weather-resistant storage of the armored tonneau for my gear.

Here are my most recent shots, and it's worth saying that the pickup model I've been using does not have a square bed, but the passenger side is slightly higher than the DS, hence some degree of "wonkiness".

Closed up:

Tailgate view:

Side view:

The smaller toolbox door will open away from the cab to facilitate being able to kick open my rear sliding windows for ease-of-reach.