Introduction: Toy Mack AC Bulldog Truck -- Part 5 -- Dump Box

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first to…

This is the fifth in a series of Instructables on the toy truck I made for my grandson (age 3). The first in the series can be found here. This Instructable will deal with making and mounting the dump box. The dump box has a working end gate and a box lift, both manipulated by hand.


  • Sheet steel from the outer skin of an old washing machine
  • 3/6 inch steel rod
  • 1/8 inch steel rod
  • 1/8 x 1/2 inch flat steel bar


  • Angle head grinder and cutting disc, grinding disc
  • Measuring and marking tools
  • Vise
  • "C" clamps
  • Spring clamps
  • Aluminum angle
  • Angle iron
  • Hammer
  • Vise Grip pliers (needle nose style)
  • Flux core wire feed welder

Step 1: Layout

The first Instructable in this series can be found here.

Mark out the sheet metal for the box. The solid lines are the outline. The dotted lines indicate folds.

I do not have a sheet metal brake. I clamped a piece of angle iron along the fold lines and bent the sheet metal . I used a hammer to make the fold line as sharp and crisp as possible. With the two sides folded up I needed to cut a piece of scrap angle iron to fit between the sides so I could clamp it to the sheet metal and fold.

Step 2: Weld

I pulled the corners together on a piece of aluminum angle and made some tack welds in the corners. I ground the welds fairly smooth when I was finished.

Step 3: Begin Framing the Box With Rod

I cut pieces of 1/8 inch rod to attach to the edges and corners of the box. This rod adds strength and helps retain the desired form. It replicates the reinforcements to a dump box. And, it covers sharp edges.

In the photo you can see rod added to the top edges and front corners of the box. Rod also outlines the edges at the rear of the box. The box is merely resting on the truck frame and is not attached, yet.

Step 4: Add Uprights

A dump box on a real truck uses numerous reinforcements. I welded more 1/8 inch rod cut to size for the uprights.

Many dump trucks have a firm name painted on the side of the box. My grandson's name is Joshua. I positioned the uprights so there are six equal spaces for the letters in his name. Those letters will be self-stick vinyl from an office supply store.

Step 5: Grind and Add

The ideal would be to use square stock for the uprights around the box, but square stock is quite expensive. I had some round rod and decided simply to grind the outer surface of the rod flat.

I also decided the end gate would attach with two hinge pieces like the one shown. I bent two of the piece shown and welded them to the upper rear corners of the box. See the next step for more information.

Step 6: The End Gate

I made the end gate by cutting a piece of 1/8 inch rod to go between the two hinge openings from the last step. Then I cut a piece of sheet metal to fit the box, but left the lower edge a bit oversize for a catch to be shown in the next step. I framed the end gate in 1/8 inch rod as shown in the photo from the finished truck.

Step 7: The End Gate Catch

The first photo is taken looking down at the bottom of the box on the rear of the truck. My hand grasps the end gate and is lifting it slightly in the hinge loops. You can see the tab left on the bottom of the end gate, also the corresponding slot in the bottom of the box to catch the tap and hold the end gate closed.

The second photo shows the elongated hinge loop that allows raising the rod at the top of the end gate.

Step 8: Attaching the Box to the Truck

The hinges between the box and the bed of the truck is two pieces of 1/8 x 1/2 inch bar bent to make two "L"s. One leg of the "L"s is welded to the bottom of the box as you can see in the photo. The other leg has been drilled for a short piece of 3/16 inch rod. I drilled a corresponding 3/16 inch hole in the sides of the truck frame near to its rear end, one on each side.

In the photo I have fit the box to the truck and checked to see that the box is aligned with the truck so the box looks right whether resting on the truck or elevated in the air. It is easy to position and weld one of the hinge "L"s to the box, but the second one must be positioned properly with little chance for error. I used a needle nose Vise Grip pliers to hold the hinge "L" while I double checked for proper positioning before welding.

It is always a challenge to weld thicker 1/8 inch material to sheet metal about 0.030 inch thick. Good penetration in the 1/8 inch material is needed, but care must be taken not to burn holes in the thinner material. I decided four good tack welds are sufficient.

Step 9: The Lift

The lift I made is hand operated, but has the appearance of two hydraulic rams on a real truck. It is made of two horizontal and two vertical rods from 3/16 inch stock.

Notice the short sections of 1/2 inch square tubing just behind the cab. These raise the front of the truck box to the height set by the box hinges at the rear of the box, making the truck box appear level, as it should be.

The second photo gives a picture of how the bottom of the lift pivots. I bent a piece of 1/8 inch rod in a curve and made one for each of the two sides. I welded them to make a bearing enclosure bounded by the frame of the truck, the 1/2 inch square tubing that keeps the box level, and the curved 1/8 inch rod. Notice where the lift supports the box. Two pieces of steel act as stops to keep the lift from sliding off the front of the box. I added a single short piece of rod behind the lift crossbar to keep the lift from settling back to its downward position prematurely. I also made a few welds to form a sort of ramp. This aids in raising the box by sliding the lift under the box. I ground this ramp smooth for ease of use.

The next part in this series can be found here.