Joining two middle boxes together??

[BikerDad]

I recently picked up a pair of the Husky 3 drawer intermediate boxes ($40 each) for my "backwall" unit, and I was cutting some shelf liner for them today. I've stacked the boxes, using a piece of 1/2" plywood wrapped with shelf liner (to keep them from sliding around) as a spacer, since they won't stack otherwise. While working with the shelf liner, the top unit decided to try to tip over. Fortunately, it couldn't because there wasn't enough top clearance, but I'd like to make sure it doesn't do it again.

So, my question for all you experienced Garage Dwellers. What is the best way of fastening/connecting the two together?

 

[zkling]

Bolt them together. Take out all the drawers drill a 4 hole pattern in the bottom of the top box. Sit on top of the bottom box, mark hole location with marker. Drill top box bottom box. Insert bolts/washers/nuts, put drawers back in. That is at least how I would do it. YMMV though

Once I went to look at a stack of older snap on boxes, top, middle, bottom. The PO had welded them together at the joints all the way around. He was surprised when I wasn't happy to find that out.

 

[Provincial]

Use "Fender" washers when you bolt them together. These are much larger in diameter than normal washers, and are designed to hold two pieces of sheet metal together. Use these washers on both sides of the joint. You will have to put your holes far enough away from the edges so the larger diameter washers will fit.