Building an ATV toolbox

Well this is finally too frustrating to put up with. After 10 good years my cheap Cabela's ATV bag is just worn out. The zipper quit working, the straps that hold it on are mostly disintegrated. This quad mostly runs around the neighborhood with some tools in the front for starting irrigation lines and fixing sprinklers, so there are several tools I like to keep in there at all times, protected from weather. So it's time to get myself a proper toolbox.

old atv bag

The plan, such as it is

Fun it would be to build this out of aluminum diamond plate, but I've just taken inventory and found 3 nice sheets of 16 gauge steel that should make for one stout toolbox. This will be an interesting challenge in making some of the parts; I've got lots of sheet metal tools that will work 20ga and 18ga steel all day long, but only a few that will work 16 gauge (about 1/16" thick), so there will probably be a fair bit of hand grinding and fitting to be done.

Much of this will be a 'design as I go' sort of project. I can foresee some areas that might still have enough flex to need some stiffening, and possibly some parts that won't be as easy to bend as I hope.

So I'm going with all steel, about 4" tall, and as flat a top as possible. Some tube railing around the top makes even more space to stack and strap a backpack, chainsaw or gas can when I'm riding a bit further from home. I want the corners to follow the rounded nature of the rack if for no other reason than it looks cool. Hopefully it will also add some needed stiffness to the lower half without needing to add a bunch of gussets or braces.

Getting started

First step was make a cardboard template to fit the rack and transfer that to the steel sheet. This will be the first use of the power shear as my 4ft stomp-shear is only rated to 18 gauge (~0.040 inches) at it's full width. It claims to work on 16ga at half-width but it flexes a bunch and requires a WWE style pile-driver onto the foot pedal to get it to cut, so in the interest of longevity (the shear's and mine) I just don't use it for that.

sheet metal base
So after some cutting, zip-wheeling and grinding, I have the bottom of what looks like a sheet metal blank for a giant playstation controller.
Adding the sides
Well, turns out the sides are going to be thinner after all. I tried some careful cutting with a cutoff wheel and a straight edge but to make the sides I just really needed to have a proper sheared edge to keep things straight and even enough. So here's current progress of the front and back. I'm not that skilled with the slip roll yet, so thinner material turned out to be easier as I could over-bend it a bit then massage it back into plate a bit at a time. This is a good place to stop cutting I think and start setting up for some welding. The front and back will get well tacked into place then I'll cut and curve the remaining side pieces.

Lining up the sides:

clamping the sides
tacking starts
Now much tacking begins. Got the front back and sides tacked in place and welded. I should have waited to tack the top too before welding. I thought clamping a thick chill-block behind the gap would hold things a little straighter. Well, the vertical welds pulled in pretty good anyway, but not all for the reasons I thought. The very bottom oil canned a bit, and pushing that back to flat caused the sides to bulge out almost to square. So I broke out the gas torch and tried some heat shrinking on the bottom. I have much respect for the auto-body guys, this is still much of a black magic to me. The bottom is still not perfect, but the sides moved out as I hoped they would. It's close enough now I think I can just force it into place when I tack in the flange.
weld distortion

The Lid

cutting out the lid
The lid was made much the same way as the bottom. It's about a 1/4" wider than the toolbox so around the front and sides would be overhang to shed water easily. The back will get piano hinge riveted on, and making that area water resistant will have to be up to the weather stripping around the perimeter.

Now as welds will do when the flange was welded on it shrunk the edges of the lid a fair bit. Much like wrapping a ratchet strap around the perimeter and squeezing it all around. This caused the center of the lid to rise up considerably, and now the whole thing sits on the bench about as flat as a bananna.

Heat shrinking the center helped a bit on the bottom of the toolbox, but I was afraid of creating more waviness in the lid that I wouldn't know how to fix. So I sat there staring at it for a bit before realizing something: it's the weld zone that shrinks. So how can I stretch the weld zone again? I decided to hold the edge of the lid over some of my smaller curve anvils and start lightly hammering back and forth across the whole thing. I started to see some change in the curve in the lid, so I kept at it. It took some time, but less than I thought and many many light hammer hits works a lot better than fewer heavy ones. The goal is just to slightly stretch the weld along the entire edge, not force a bent object back to straightness.

So now I've got a handle on that it's time to mount the latch parts. I made a nice doubler plate by milling a window in a piece of stainless from the scraps shelf and then ground out a slightly larger hole in the box itself with a cut-off wheel and an air file.
cutting out the latch hole latch installed
Then it came time to layout where the catch would go in the lid...

Before you see this, I'm OK

dykem accident
These are the words I said as I trotted into the house, my pants covered in dripping red liquid in just the right spot to quite shockingly look like I'd just been stabbed in the femoral artery. Thankfully the liquid wasn't blood but red Dykem. Dykem is a brand name of marking fluid for metal, leaves a colored surface that makes precise scribe-lines show up clearly. It comes in red and blue colors. The bottles have a foam top that you squeeze a bit to get some fluid into, and then brush onto the surface. I was preparing to layout and drill the rivet holes for the lid catch. Instead what I got was the top of the bottle coming off as I turned it over and squeezed slightly. So out came over a half-ounce of bright red liquid all over the toolbox, down the front of the workbench, my pants, and onto the floor.

The culprit:

dykem bottle
I did take the time to laugh at myself and the apparent murder scene that the welding bench now looked like. Didn't think to get a photo of the pants, I just went right up to the house to see if I could start washing the dye out somehow. Guess what? That stain's never ever coming out. It did fade a little bit, so now some khaki work pants have a stain that looks more like red wine and less like car crash victim.

Now where was I?

Well alright, everything else was pretty straightforward. Drill holes for hinges, bolt on the catch, grind prime and paint.
lid install
I found some nice outdoor weatherstripping at the local hardware store. It's 5/16" tall and fairly soft, so it squishes down nicely when the lid is closed. Very well sealed, helps hold pressure on the latch too, gives it a real solid feel when you open it. So I used a good etching primer, some tan paint that I thought went with the green quad, and rubberized truck-bed liner for the inside. Finally, here it is all mounted up:
finished box installed box with lid open

Conclusion

Besides getting cool custom stuff my goal in building things is always to learn something about how to do it better next time. The best lessons I got from this were controlling distortion while welding sheetmetal and also correcting it after the fact. Hammering out the welds on the lid edge took much less effort than I thought it would to stretch that area and return it to reasonable flatness. Many light taps across the edge of the weld is the key. I also learned to check the cap on the Dykem bottles... every ...single ... time...

Other than that, more time under the welding hood is better, faster, smoother TIG welds.

Final shot with the ATV in its natural habitat, fixing handline and sprinklers again.
in the field